PROMISSORY AGREEMENT
                         OF SALE AND PURCHASE OF SHARES


     ANTONIO  BRANDAO  MIRANDA  (hereinafter  referred  to as ANTONIO  MIRANDA),
married under the legal regimen of separation, born at Argivai, Povoa de Varzim,
resident at Rua do Molhe,  nr.27, Porto,  Portugal and AMTROL Inc.  (hereinafter
referred to as AMTROL),  with head offices at 1400 Division Road,  West Warwick,
Rhode Island, United States of America,  hereby represented by its attorney Jose
Carvalho de Freitas,  whose  quality and powers for this act are proved by power
of  attorney,  the  original of which  shall be  attached  to ANTONIO  MIRANDA's
counterpart  of this  Promissory  Agreement,  being a copy  attached to AMTROL's
counterpart.


HAVING REGARD THAT:

     A)  ANTONIO  MIRANDA  is, on  today's  date,  the sole  owner of the shares
representing  the share capital of "PETROLEO  MECANICA ALFA,  SA."  (hereinafter
referred to as ALFA) with head offices at Brito, Guimaraes, Portugal;

     B) AMTROL wants to purchase and ANTONIO  MIRANDA  wants to sell the 300.000
shares representing the share capital of ALFA;

     C) For such purpose ANTONIO MIRANDA and AMTROL signed a letter of agreement
on 07th  of May  1997,  whereby  both  parties  undertook  to  enter  into  this
promissory agreement on today's date;

     D) In  accordance  with  such  letter of  agreement,  AMTROL,  with  ALFA's
consent,  obtained from ANTONIO  MIRANDA,  ordered an audit,  made with auditors
chosen by it - Arthur  Andersen - to ALFA's  accounts  as of 31  December  1996,
having ANTONIO MIRANDA received a copy of such report.


     The above identified parties agree to enter into this Promissory  Agreement
of sale and purchase of Shares,  made on the 30th day of June 1997,  which shall
be governed by the following provisions:

                                    CLAUSE 1
                                   Definitions

     1. In this  agreement the following  words and  expressions  shall have the
following meanings:

1.1. SHARES:

     The totality of shares  representing  ALFA's share capital, on today's date
held by ANTONIO MIRANDA, the sale and purchase of which is the subject matter of
the present Promissory Agreement;

1.2.      AMTROL:

     AMTROL or any  company  controlled  by  AMTROL,  to whom this  assigns  the
contractual position under the terms of clause 18;

1.3. ESCROW BANK:

     BPI - Banco  Portugues  do  Investimento,  SA.,  with head  offices  at Rua
Tenente Valadim,  nr.284, 4100 Porto,  Portugal,  with whom the escrow agreement
attached to this Promissory Agreement as Annex I was entered into;


1.4. COMPLETION:

     Completion  of the sale and  purchase  Final  Agreement  of the Shares,  in
accordance with clause 6;

1.5. FINAL AGREEMENT:

     The final agreement to be entered into between the  undersigned  Parties or
between those they for such purpose indicate;

1.6. PROMISSORY AGREEMENT:

     This  agreement,  whereby the Parties  promise to sell and to purchase  the
Shares

1.7. COMPLETION DATE:

     The date of signature of the Final Agreement on the 22nd of December 1997;

1.8. INDEMNIFICATION ESCROWED AMOUNT:

     The escrowed amount  corresponding to the damages claimed by AMTROL and not
accepted by ANTONIO MIRANDA up to one million Dollars (USD 1,000,000),  together
with all respective earnings;

1.9. FINAL DEPOSIT:

     The  deposit  of the  amount of five  millions  and five  hundred  thousand
Dollars  (USD  5,500,000),  reduced,  as the case may be,  by the  amount of the
Indemnification  Escrowed  Amount,  and/or by the  quantified  amount of damages
claimed by AMTROL,  until  Completion  Date,  and which  have been  accepted  by
ANTONIO MIRANDA, through written document signed by both Parties;

1.10. INITIAL ESCROWED AMOUNT:

     The amount of fourteen  millions  Dollars (USD  14,000,000)  referred to in
paragraph b) of number one of clause 5,  together  with the  respective  accrued
interest, or reduced under the terms of number four of clause 20;

1.11. BUSINESS DAY:

     A day,  other than a Saturday or Sunday,  on which banks are open generally
for business in Porto and Rhode Island;

1.12. DOLLAR:

     The legal currency of the United States of America;

1.13. COMPANY or ALFA:

     The Portuguese  company  "PETROLEO  MECANICA ALFA,  SA.",  collective  body
number 500 216 738, registered before the Commercial Registry of Guimaraes under
number 1504, with head offices at Brito, Guimaraes, Portugal;

1.14. ENCUMBRANCE:

     Any mortgage,  pledge, lien,  encumbrance or other security interest of any
nature over the whole or any part of the  Company or over any of the Shares,  as
the case may be;


1.15. PARTIES:

     The undersigned ANTONIO MIRANDA and AMTROL, or who this latter indicates as
purchaser until Completion Date, in accordance with clause 6;

1.16. TAXATION:

     All  forms of  taxation,  duties,  imposts,  surcharges,  levies  and rates
imposed in Portugal,  including without  limitation,  imposto sobre o rendimento
das pessoas colectivas (IRC),  imposto sobre o rendimento das pessoas singulares
(IRS), imposto sobre o valor acrescentado (IVA), imposto de selo,  contribuicoes
para a seguranca social,  contribuicao autarquica,  imposto sobre as sucessoes e
doacoes,  imposto  municipal  de SISA,  taxas  alfandegarias,  or other  similar
contributions  and,  in general,  any  interest,  penalty or fine in  connection
therewith and cognate words such as "Tax",  "Taxes",  "Taxation  liability"  and
similar shall be similarly defined;

     2. The Annexes to this  Promissory  Agreement form part of this  Promissory
Agreement  and shall have the same force and  effect as if  included  within the
body of this Promissory Agreement and any reference to this Promissory Agreement
shall include Annexes hereto.


                                    CLAUSE 2
                          Promise of sale and purchase

     1. ANTONIO MIRANDA promises to sell and AMTROL promises to purchase all the
Shares, with a nominal value of PTE 1.000$00 each,  representing the totality of
ALFA's share capital.

     2. AMTROL may indicate,  until ten days before  Completion  Date, a company
fully held by it to enter into the Final Agreement under its own name.

     3. ANTONIO MIRANDA guarantees that there are no Encumbrance over the Shares
and that these are not by any form subject to any obligation which might prevent
the  Completion of the Final  Agreement on Completion  Date,  under the terms of
clause 6.

                                    CLAUSE 3
                                      Price

     The  price for the sale and  purchase  of the  Shares  agreed  between  the
Parties is of USD  25,500,000  (twenty five  millions and five hundred  thousand
Dollars).

                                    CLAUSE 4
                                     Payment

     1.  On  today's  date,  AMTROL  pays  ANTONIO  MIRANDA  the  amount  of USD
20,000,000 (twenty millions of Dollars), as earnest and down payment, being such
payment done in accordance with clause 5.

     2. On Completion Date AMTROL shall pay ANTONIO MIRANDA the remaining of the
price, i.e. the amount of USD 5,500,000 (five millions and five hundred thousand
Dollars) through deposit with the Escrow Bank.


                                    CLAUSE 5
                            Earnest and down-payment

     1. The amount of USD 20,000,000  (twenty millions  Dollars)  referred to in
number one of clause 4, is paid as follows:

     a) the amount of USD  6,000,000  (six  millions  Dollars) is  delivered  on
today's  date to ANTONIO  MIRANDA,  which he gives his  acquittal  for,  through
deposit in account number  80008.9,  opened at the Escrow Bank under the name of
Antonio Brandao Miranda;

     b) the amount of USD 14,000,000 (fourteen millions Dollars) is paid through
deposit with the Escrow Bank, regulated by the terms of conditions of the escrow
agreement as established in Annex I, in a bearing interest escrow account, being
interest at a 7% yearly rate, opened in a foreign subsidiary of the Escrow Bank,
for the benefit of ANTONIO MIRANDA and AMTROL;

     2. ANTONIO  MIRANDA,  in accordance with the terms of the escrow  agreement
included  in Annex I, or his heirs,  shall be  entitled  to receive  the Initial
Escrowed Amount,  when the Shares are transferred to AMTROL,  in accordance with
clause 7.

                                    CLAUSE 6
                                   Completion

     1. The Final  Agreement  shall be  entered  into,  at Porto,  Portugal,  by
ANTONIO  MIRANDA and by AMTROL or by a company,  directly or  indirectly,  fully
held  and/or  controlled  by  AMTROL,  indicated  until  10  (ten)  days  before
Completion Date.

     2. If the Final  Agreement is not executed by AMTROL but by another company
fully  controlled by it,  AMTROL,  together  with the  indication of the company
which is going to be party in the Final Agreement and acquire the Shares,  shall
give ANTONIO MIRANDA the necessary  documents to prove the incorporation of such
company,   AMTROL's   ownership  of  the  company's   share  capital,   and  the
identification  of the person with powers to represent the company on Completion
of the Final Agreement.


                                    CLAUSE 7
                               Transfer of Shares

     1. The  Shares  shall be  definitively  sold and  transferred  to AMTROL on
Completion  Date, with the signature of the Final Agreement and upon delivery by
the Escrow  Bank to ANTONIO  MIRANDA of the  Initial  Escrowed  Amount and Final
Deposit.

     2. If the  Agreement is not signed on  Completion  Date the Shares shall be
considered  as sold and  transferred  to AMTROL if this deposits with the Escrow
Bank,  within the next five  Business  Days  after  Completion  Date,  the Final
Deposit,  together  with the Final  Agreement,  signed by AMTROL on date of this
joint delivery, in accordance with the draft hereto attached as Annex II and the
Escrow  Bank  simultaneously  puts at ANTONIO  MIRANDA's  disposal  the  Initial
Escrowed Amount and the Final Deposit.

     3.  From  today's  date  and  until  Completion  Date the  Shares  shall be
deposited in a bank  escrowed  account for this  purpose  opened with the Escrow
Bank,  in  accordance  with the terms  and  conditions  set forth in the  escrow
agreement included in Annex I.

     4. From today's date and until  Completion,  and if so requested by ANTONIO
MIRANDA,  the Escrow Bank shall provide him with proof of exclusive ownership of
the Shares, for participation in ALFA's general meetings purposes.

     5. In  accordance  with the  terms  and  conditions  set out in the  escrow
agreement included in Annex I, the following shall be applicable:

     a) the  Escrow  Bank  shall  give  the  deposited  Shares  to  AMTROL  upon
exhibition of the original of the Final Agreement, signed by both Parties;

     b) upon delivery  with the Escrow Bank of the Final  Deposit  together with
the Final  Agreement,  signed on the date of such  delivery,  under the terms of
number two of this  clause,  the Escrow Bank shall  deliver the Shares to AMTROL
and shall put at ANTONIO MIRANDA's  disposal the Initial Escrowed Amount and the
Final Deposit;

     c) the Shares may be delivered to ANTONIO  MIRANDA from the fifth  Business
Day onwards after Completion Date if AMTROL has not previously  exhibited to the
Escrow Bank the Final  Agreement  signed by both Parties,  or if AMTROL does not
make the Final Deposit;

     d) If the situation  referred to in the previous  number occurs and ANTONIO
MIRANDA does not ask for the delivery of the Shares until the twentieth Business
Day,  inclusive,  after Completion Date, the Escrow Bank shall deliver to AMTROL
the Initial Escrowed Amount;

     e) However,  if ANTONIO MIRANDA has, previous to the extinction of the term
referred to in the  previous  paragraph,  notified  the Escrow Bank that he will
submit to arbitration a situation of faulty breach of this Promissory  Agreement
by AMTROL and  effectively  does so within the fifty Business Days counting from
Completion  Date, the Escrow Bank shall only deliver to AMTROL the amount of USD
10,000,000 (ten millions Dollars) from the Initial Escrowed Amount,  which shall
be reduced to USD 4,000,000 (four millions Dollars), being such amount delivered
by the Escrow Bank in accordance with the decision of the arbitral tribunal;

     6.  However,  the Shares shall be  considered  as sold to AMTROL on today's
date, if ANTONIO  MIRANDA dies on or before the  Completion  Date, in which case
the Escrow Bank shall  deliver the Shares to AMTROL upon proof,  by this latter,
of the death of ANTONIO MIRANDA,  through death certificate and upon delivery to
the Escrow Bank of the Final  Deposit,  which (the Escrow Bank) shall put at the
disposal of ANTONIO  MIRANDA's  heirs both the Initial  Escrowed  Amount and the
Final Deposit.


                                    CLAUSE 8
                        Patrimonial rights of the Shares

     1. All  patrimonial  rights  relating  to the  Shares or to the  quality of
shareholder,  verified from 1st January 1997,  shall be transferred to AMTROL on
Completion  Date or on the date  established  in  paragraph  six of the previous
clause if the conditions thereof mentioned are verified.

     2.  The  patrimonial  rights  mentioned  in the  previous  paragraph  shall
include, namely and without limitation:

     a) right to profits or dividends;

     b) right to shareholder's loans to ALFA;

     c) right to subscribe increases of the Company's issued share capital;

     d) right to supplementary capital / equity;


                                    CLAUSE 9
                          Intellectual property rights

     1. ANTONIO MIRANDA grants AMTROL or ALFA, by choice of the former (AMTROL),
the right to use the word COMANOR as a non-registered trade mark.

     2. ANTONIO  MIRANDA  further  undertakes  not to prevent or  difficult  the
registry of the trade mark COMANOR under the name of AMTROL or ALFA,  giving his
express authorisation, if need be, for such purposes.


                                    CLAUSE 10
                                 Non-competition

     ANTONIO  MIRANDA  undertakes  not to  exercise,  for a term of  five  years
counting from Completion Date, any activity which directly or indirectly compete
with  the  activity  carried  out  by  ALFA,  which  is the  manufacture  and/or
reparation  or  requalification   (refurbishment?)  of  reusable  or  disposable
containers, used for G.P.L., for refrigerating gases or for technical gases.


                                    CLAUSE 11
                         Representations and warranties

     ANTONIO MIRANDA guarantees that, as to 30th June 1997:

     a) The Company is a corporation  duly  organised,  validly  existing and in
good standing under the laws of Portugal, having no subsidiaries;

     b)  ALFA's  accounts  closed  on 31st of  December  1996  reflect  the real
economic  and  financial  situation  of the  Company,  as well  as  that  ALFA's
accountancy  instruments,  containing  balance sheets as of 31 December 1996 and
31st May 1997,  included in Annex III,  have been  prepared in  accordance  with
generally accepted accounting  principles  consistently  followed by the Company
throughout the periods  indicated,  and that there has not been,  from such last
date until today, any significant change in its financial situation;

     c) ALFA does not have any concealed liabilities, responsibilities or funds,
which are not  revealed  in its  accounts,  nor there are over the  Company  any
Encumbrances,  but ALFA is bound by a promise of  constituting a commercial pawn
over equipment and mortgage over the real estate located at lugar de Pontilhoes,
parish of Brito,  city council of Guimaraes,  registered  before urban matrix of
the local tax  department  under  number 552 and 637 and  registered  before the
Predial  Registry  under number 00932,  to be  constituted in favour of Banco de
Fomento  Exterior,  EFTA  Fund,  Banco  Espirito  Santo  e  banco  Portugues  do
Investimento,  in case of faulty  breach  for more than  forty-five  days of the
obligations  assumed by it before the mentioned  banks and Fund in the financing
agreement,  with them  entered  into on 20th of June  1995,  to whom it  granted
irrevocable proxy for the constitution of such commercial pawn and mortgage;

     d) The Shares have been duly issued ad are fully paid; the Shares represent
all of the  capital  of ALFA and there  are no  outstanding  subscriptions,  nor
options  in favour of others;  apart  from what is set forth in this  Promissory
Agreement,  there are no  promises  of sale or options  for the  purchase of the
Shares,  nor  rights,  warrants,  convertible  securities  or other  agreements,
commitments  or claims of any  character  which limit or relate to the transfer,
purchase, issuance or sale of any shares of capital stock of ALFA, other than as
contemplated by this Promissory Agreement;

     e) He owns all of the Shares,  free and clear of all  Encumbrances;  he has
full legal right, power and authority to enter this Promissory Agreement, and no
approvals or consents of any other person,  apart from those referred hereby to,
are necessary in connection with this  Promissory  Agreement or with the sale of
the  Shares;  with  the  delivery  to  AMTROL  of the  Shares  pursuant  to this
Promissory  Agreement or to the Final  Agreement  valid title thereto,  free and
clear of all Encumbrances will be transferred to AMTROL;

     f) ALFA has not issued any securities  convertible into Shares or any other
securities which may be convertible into Shares;

     g) All legal  proceedings  and files  pending  before  any  administrative,
judicial or other  official  entities  ALFA  currently  is party to are the ones
listed in Annex IV;

     h) ALFA is not  engaged,  as the moving or  defending  party,  in any other
litigation,  arbitration,  administrative or other  proceeding,  nor to his best
knowledge is any other proceeding of such nature threatened against ALFA;

     i) Except for the  contracts  described  in Annex V, ALFA is not a party to
any  important  contract  of  continuous  execution  with  more than one year of
duration,  including  contracts  with  suppliers or  customers,  relating to the
Company's business;

     j) ALFA has not violated all applicable  laws,  ordinances and regulations,
including  without  being limited to,  building and zone laws,  laws relating to
employees and  conditions of  employment,  and  environmental  requirements  and
specifications relating to the Company's business;

     l) The  consummation  of the  transaction  contemplated  by this Promissory
Agreement will not constitute any of the following:

     (i) a default or event that, with notice or passage of time or both,  would
be a default, breach or violation of ALFA's articles of association,  any lease,
license,  promissory note, contract,  commitment,  indenture,  mortgage, lien or
other agreement,  instrument or arrangement to which ALFA is a party or by which
it or its property is bound;

     (ii) an event that would permit any party to terminate  any agreement or to
accelerate the maturity of any indebtedness or other obligation of ALFA;

     (iii)  the  creation  or  imposition  of any  Encumbrance  of any on ALFA's
properties;

     m) None of the  representations  and  warranties  herein  made  contain any
untrue  statement  of material  fact or omits to state any  material  fact,  the
omission of which would be misleading to AMTROL;


                                    CLAUSE 12
                                  Undertakings

     ANTONIO  MIRANDA  undertakes  to,  between  the  time  of  this  Promissory
Agreement and Completion Date:

     a) without AMTROL's  consent,  not to pass any resolution in ALFA's general
meeting or by way of written resolution which:

       (i)         is or may be in opposition with the attribution to AMTROL of 
                   all patrimonial  rights relating to the Shares from 1st
                   January 1997;
       (ii)        increases ALFA's share capital;
       (iii)       requires  ALFA  to  pay  dividends  or   make   any    other 
                   distribution;
       (iv)        alters or may alter the provisions of ALFA's articles of 
                   association;
       (v)         modifies ALFA's corporate year end;
       (vi)        changes ALFA's residence for taxation purposes;
       (vii)       constitutes a  decision to declare or make any  dividend  or
                   other distribution;
       (viii)      implies the  dismissal or nomination of directors or members 
                   of ALFA's  corporate  bodies, unless such action is required 
                   by law for  the  purposes  of  ratifying  the  cooptacao  of
                   directors for the fulfilment of vacant places in the board;

     b) not to vote  against or prevent any  deliberations  requested by AMTROL,
which  are  necessary  to keep the  normal  course of  ALFA's  business,  to the
execution of the Final  Agreement on Completion  Date and to the  maintenance of
the patrimonial rights arising from it;

     c) not to demand from ALFA the payment of any loans he may have  granted or
may be entitled to;

     d)  make  COMANOR  SA.   moves  for  ALFA  the  painting   line  and  steel
refurbishment equipment located at its former establishment;

     e) not to create Encumbrances over any of the Shares;

                                    CLAUSE 13
                                Will to contract

     1. The  Parties  expressly  acknowledge  and  accept  that this  Promissory
Agreement  is  entered  into  in  reliance  upon  each  of the  representations,
warranties and  undertakings  hereby given and assumed,  which are considered as
fundamental  elements for the will of the Parties to enter into this  Promissory
Agreement and to transfer and acquire the Shares.

     2. If, after the signing of this Promissory Agreement and before Completion
Date,  any  event  shall  occur or matter  arise  which in any way  affects  the
accuracy of any of the above representations,  warranties and undertakings until
Completion's date, ANTONIO MIRANDA shall immediately notify AMTROL in writing.


                                    CLAUSE 14
                               Mis-representations

     1. If the representations and warranties herein given by ANTONIO MIRANDA do
not  represent  the true and  accurate  situation  of the Company  and/or if the
undertakings  herein assumed by ANTONIO  MIRANDA are not complied  with,  having
this  mis-representation  and/or non compliance the result of causing damages to
AMTROL by means of  considerable  depreciation  of the value of the Shares or of
the Company,  ANTONIO  MIRANDA shall be  responsible  for  compensation  of such
damages  if they are  verified  from  today's  date  until 30th June 1999 and if
AMTROL presents a justified and written claim,  one for each damage,  until such
date.

     2. For the  purposes  mentioned  in the  previous  number,  a  considerable
depreciation  is  deemed to occur  where a single  claim is for or  exceeds  the
amount of five  millions of  Portuguese  escudos (PTE  5,000,000)  or if several
claims of lower  amount,  considered  together,  are for or exceed the amount of
fifty millions of Portuguese escudos (PTE 50,000,000).

     3.  Notwithstanding  the above  established  in the previous  numbers,  the
following shall be applicable:

     a) if any damage is identified  before Completion Date and if it is subject
to quantification and evaluated up to the amount of USD 5,500,000 (five millions
and five hundred thousand Dollars),  on Completion Date, the agreed price of the
Shares shall be reduced for an amount equal to such damage;

     b) if any damage is identified  before Completion Date and if it is subject
to  quantification  and exceeds the amount of USD 5,500,000  (five  millions and
five hundred thousand  Dollars),  AMTROL may choose to reduce the price for such
amount of USD 5,500,000 (five millions and five hundred thousand  Dollars) or to
denounce this Promissory Agreement, under the terms of clause 20;

     c) if any  damage is  identified  before  Completion  Date and if it is not
subject to  quantification,  AMTROL may be entitled to denounce this  Promissory
Agreement,  if the  condition  established  under number  three  paragraph b) of
clause 20 is verified;

     4. If, in accordance with paragraphs a) and b) above,  AMTROL  considers an
adjustment  to the price of the Shares  occurs,  and  ANTONIO  MIRANDA  does not
agree,  the amount of USD  5,500,000  (five  millions and five hundred  thousand
Dollars) due on Completion Date in accordance with clause 4, shall be handled as
follows, as Final Deposit:

     a) the amount of  adjustment  considered by AMTROL up to the maximum of USD
1,000,000  (one  million  Dollars)  shall be  deposited  with the Escrow Bank as
Indemnification  Escrowed Amount, subject to the terms established by the escrow
agreement hereto attached as Annex I;

     b) the  remaining  of the price  shall be paid to ANTONIO  MIRANDA  through
deposit with the Escrow Bank.

     5. The Parties herein undertake to submit the interpretation, qualification
or decision of any situation of mis-representation or non-compliance, as well as
of quantification of respectively caused damages,  before the arbitral tribunal,
under  the  terms of clause  22,  if they do not  reach an  agreement  upon such
interpretation, qualification, decision or quantification.

     6. AMTROL  grants to ANTONIO  MIRANDA  the right to directly or  indirectly
intervene in any  negotiation  or to contest any claim brought by third parties,
based  on  any   situation   which  may  be  deemed  as   misrepresentation   or
non-compliance  with any undertaking hereby made and assumed by ANTONIO MIRANDA,
being  able,  for  such  purposes,  to  substitute  ALFA or  AMTROL,  appointing
attorneys  at law of his  confidence,  providing  the  guarantees  or making the
deposits  eventually  demanded  from this latter;  AMTROL  undertakes  to inform
ANTONIO MIRANDA when any claim is brought and to allow him to directly intervene
in any legal,  administrative or other proceeding in any way related with any of
such  claims,  and to  freely  provide  him with all the  information  and other
material necessary means for the contestation of such claims.


                                    CLAUSE 15
                                    Taxation

     1. ANTONIO  MIRANDA shall be liable to pay ALFA, from today's date onwards,
any  amount  which it may be  required  in  respect  of any  Taxation  liability
relating to any  business or other  actions  conducted by ALFA until 1st January
1997,  to the  extent  such  amounts  are not  fully  provided  for in the  1997
accounts;  ANTONIO  MIRANDA  shall  also be  liable  to pay ALFA any  amount  of
Taxation  for which it may be liable  constituting  fines and  interest  due and
accrued related to facts occurred between 1st January 1997 and 30th June 1997.

     2.  The  rights  and  obligations  established  under  clause  14  shall be
applicable, with the necessary adaptations, to any claim related with Taxation.

     3. The rights  arising  from this  clause for AMTROL  shall  elapse on 31st
December 2001,  save in what concerns any fines, in which case they shall elapse
on 30th June 2002.


                                    CLAUSE 16
                              Specific performance

     Further to specific performance of the Agreement  established under numbers
two and six of clause 7 and notwithstanding the amount paid as down payment, any
of the Parties may request before the arbitral tribunal the specific performance
of  this  Promissory  Agreement,  in  order  to  obtain  the  judicial  decision
substituting the contractual declaration of the missing Party.


                                    CLAUSE 17
                       Communications and confidentiality

     1. Save AMTROL's legal obligations,  no public  communication or disclosure
by means of literature  or trade shows in  connection  with the existence or the
subject  matter of this  Promissory  Agreement or any ancillary  matter shall be
made or issued by or on behalf of any of the Parties.

     2.  Except for the  disclosure  of  information  to a Party's  professional
advisers,  auditors  and  bankers,  each Party shall treat as  confidential  all
information received or obtained as a result of entering into or performing this
Promissory Agreement.

                                    CLAUSE 18
                                   Assignment

     The  Parties  agree  that  the  contractual  position  of  AMTROL  in  this
Promissory Agreement and in all other instruments  complementing it, may only be
assigned to a company,  directly or indirectly,  fully controlled by AMTROL, and
that such assignment shall not require the prior consent of ANTONIO MIRANDA.

                                    CLAUSE 19
                                Further assurance

     Following  Completion,  ANTONIO  MIRANDA shall  co-operate  with AMTROL and
shall sign and  deliver  to AMTROL  all  documents  which are  necessary  to the
transfer of the Shares,  and to the fulfilment of the  obligations  arising from
clause 9.

                                    CLAUSE 20
                                   Termination

     1. ANTONIO MIRANDA shall be entitled to denounce this Promissory  Agreement
if  AMTROL  does not sign the  Agreement  or if it does not  deposit  the  Final
Deposit, in accordance with the terms of this Promissory Agreement.

     2.  ANTONIO  MIRANDA  shall also be entitled to  denounce  this  Promissory
Agreement  if,  until 19th of  December  1997,  no tacit or express  decision of
non-opposition  to the  Final  Agreement  made  under  the  terms  of the law on
operations of concentration is issued following the notification  AMTROL intends
to file and a copy of which shall give to him,  after such  filing,  which shall
occur until the 15th of July 1997.

     3. AMTROL  shall be  entitled,  until  Completion  Date,  to denounce  this
Promissory Agreement if any of the following circumstances occurs:

     a) If the  situation  foreseen  in number  three,  paragraphs  b) and c) of
clause 14 is verified;

     b) If ALFA is prevented  from  exercising  its activity or any event occurs
which diminishes  ALFA's  possibilities of exercising its activity in such a way
it becomes economically meaningless;

     c) If the  transaction  herein  agreed has not been duly  authorised by the
authorities with jurisdiction on competition law, if such  authorisation  proves
to be necessary for the Agreement to be executed;

     d) If the transaction is authorised subject to certain untenable conditions
for AMTROL making the present transaction as economically meaningless;

     4. If  termination  is  caused  by  AMTROL's  fault,  ANTONIO  MIRANDA,  as
contractual fine, shall use as his own the amount of USD 6,000,000 (six millions
Dollars)  and shall be entitled to withdraw  the amount of USD  4,000,000  (four
millions Dollars),  plus accrued interest,  from the Initial Escrowed Amount; if
ANTONIO MIRANDA is the faulty part, he shall reimburse AMTROL with the amount of
USD  6,000,000  (six millions  Dollars) he received  from it in accordance  with
number one paragraph a) of clause 5 of this  Promissory  Agreement and shall pay
it the amount of USD 10,000,000  (ten millions  Dollars),  as contractual  fine,
loosing all and any right to the Initial Escrowed Amount.

     5. If the Promissory  Agreement is terminated under the terms of number two
of this clause and paragraphs  b), c) and d) of number three of this clause,  or
under the terms of number one of this clause for a fact not imputable to AMTROL,
or if the execution of the Final Agreement becomes impossible due to a cause not
imputable to any of the Parties, ANTONIO MIRANDA shall reimburse AMTROL with the
amount of USD 6,000,000 (six million  Dollars) and shall loose all and any right
to Initial Escrowed Amount.

                                    CLAUSE 21
                                    Survival

     All and each of the  representations,  warranties and  undertakings  hereby
assumed by each of the  Parties are valid and  enforceable  on their own, if the
Shares are  transferred  to AMTROL and  regardless of the signature of the Final
Agreement on Completion Date and of the contents of the Final Agreement.


                                    CLAUSE 22
                                Arbitral Tribunal

     All disputes arising out of this Promissory Agreement shall be definitively
decided  in  accordance  with  Regulamento  do  Tribunal  Arbitral  do Centro de
Arbitragem  Comercial da Camara de Comercio e Industria  Portuguesa / Associacao
Comercial  de Lisboa e da Camara de Comercio e Industria  do Porto /  Associacao
Comercial do Porto,  by one or more  arbitrators in accordance  with such Rules.
The Arbitration shall take place in Porto, Portugal.

                                    CLAUSE 23
                                 Applicable law

     Both this Promissory Agreement and the Final Agreement shall be governed by
and construed in accordance with the laws of Portugal.


                                    CLAUSE 24
                                    Headings

     The headings contained in this Promissory  Agreement and the Annexes hereto
are  inserted  for  convenience  of  reference  only and shall not be taken into
account in the interpretation of any provisions of this Promissory  Agreement or
Annexes.


                                    CLAUSE 25
                                     Notices

     1. Any notice or  communication  given  under the terms of this  Promissory
Agreement shall be in writing and shall be sufficiently given if addressed to:

     a) ANTONIO BRANDAO MIRANDA, c/o Calves, SA., Rua de Gondarem,  nr.956, 4150
Porto,  Portugal,  with copies to Mr. Joao Vieira de Castro,  Largo do Adro,  9,
4050 Porto, Portugal;

     b) AMTROL Inc,  1400 Division  Road,  West  Warwick,  Rhode Island,  United
States of America,  to the attention of Mr. Edward J. Cooney, with copies to Mr.
Jose de  Freitas,  Av. da  Boavista,  1383 - 2, 4100  Porto,  Portugal,  and Ms.
Margaret  Farrell,  1500 Fleet Center,  Providence,  Rhode Island 02903,  United
Sates of America;


                                    CLAUSE 26
                                  Counterparts

     This Promissory  Agreement is executed in two counterparts each of which is
an original.

                                    CLAUSE 27
                             Condition of suspension

     The validity and  effectiveness of this Promissory  Agreement are dependant
upon the payment,  on today's date,  of the amount of six millions  Dollars (USD
6,000,000)  to ANTONIO  MIRANDA by AMTROL,  and upon the deposit by this latter,
also on today's  date, of the Initial  Escrowed  Amount with the Escrow Bank, in
accordance  with the terms of this  Promissory  Agreement  and escrow  agreement
hereto  attached  as Annex I, on both cases with  today's  relevant-date  and on
today's date communicated to ANTONIO MIRANDA by the Escrow Bank.

                                                        Porto, 30th of June 1997



ANTONIO BRANDAO MIRANDA                              AMTROL, Inc.






                              PROMISSORY AGREEMENT

                       ON THE SALE AND PURCHASE OF SHARES

                                     ANNEX I



                                ESCROW AGREEMENT

AMONG

     ANTONIO BRANDAO MIRANDA (hereinafter  referred to as ANTONIO MIRANDA or the
VENDOR),  married, born at Argivai,  Povoa de Varzim,  resident at Rua do Molhe,
nr.27, Porto, Portugal 

and 

     AMTROL Inc. (hereinafter referred to as AMTROL or the PURCHASER), with head
offices at 1400  Division  Road,  West Warwick,  Rhode Island,  United States of
America,  hereby  represented  by its attorney Jose  Carvalho de Freitas,  whose
quality and powers for this act are proved by power of attorney, the original of
which shall be  attached  to ANTONIO  MIRANDA's  counterpart  of the  Promissory
Agreement,  being  a copy  attached  to  AMTROL's  counterpart,  

and 

     BPI - BANCO  PORTUGUES DO  INVESTIMENTO,  SA.  (hereinafter  referred to as
"Escrow Bank"),  collective body number 503569046, with the share capital of PTE
35.036.000.000$00,  registered  before the  Commercial  Registry  of Porto under
number  52258,  with head offices at Rua Tenente  Valadim,  nr.284,  4100 Porto,
Portugal,  hereby represented by Mr. Mario Pereira Pinto and Mr. Jorge Alexandre
Lopes de Sa Simoes Cortez;


     THE  PRESENT  ESCROW   AGREEMENT   (hereinafter   referred  to  as  "Escrow
Agreement")  IS  ENTERED  INTO,  BEING  REGULATED  BY  THE  FOLLOWING  RECITALS,
DEFINITIONS AND PROVISIONS:



WHEREAS:

     A) ANTONIO  MIRANDA and AMTROL  entered into a Promissory  Agreement on the
sale and  purchase  of the  Shares,  on the 30th June  1997,  where the sale and
purchase of the Shares was  promised  for the price of twenty five  millions and
five hundred thousand Dollars (USD  25,500,000),  under the terms and conditions
thereof established;

     B) Under the terms of the Promissory  Agreement  AMTROL is going to deliver
by means of this Escrow Agreement, on the 30th of June 1997, to the Escrow Bank,
the  amount  of  fourteen  millions  Dollars  (USD  14,000,000),  as part of the
down-payment  of twenty  millions  Dollars (USD  20,000,000),  being such amount
deposited  at the Escrow  Bank  subject to the  conditions  established  in this
Escrow Agreement;

     C) Under the terms of the Promissory  Agreement,  ANTONIO MIRANDA, is going
to deliver by means of this Escrow  Agreement,  on the 30th of June 1997, to the
Escrow Bank,  the Shares,  which shall be there  deposited in an account  opened
under ANTONIO  MIRANDA's and AMTROL's  names,  being this deposit subject to the
conditions established in this Escrow Agreement;

     D) The  Promissory  Agreement  establishes  that as  consideration  for the
transfer of the Shares,  AMTROL shall pay ANTONIO  MIRANDA,  on Completion Date,
the Final Deposit;

     E) From the  Final  Deposit,  AMTROL  shall be able to  deposit,  up to the
amount of one  million  Dollars  (USD  1,000,000)  as  Indemnification  Escrowed
Amount,  with the Escrow Bank,  the amount  corresponding  to the damages it has
eventually  claimed before  Completion Date, which have been caused by virtue of
inaccuracies  in the  warranties  and  representations  provided or by virtue of
non-compliance  with the  undertakings  assumed  by ANTONIO  MIRANDA,  which are
subject to quantification  and not accepted by him, as well as those liabilities
arising  from  Taxation;  this  deposit  shall  be  subject  to  the  conditions
established in the present Escrow Agreement;

     F) The conditions  foreseen by this Escrow Agreement shall be applicable to
all earnings born by the deposited amounts referred to in the above recitals;


DEFINITIONS:

     The following words and  expressions  shall have the meaning hereby defined
when initialised with capital letters, either singular or plural.

1. Shares

     the totality of the shares  representing  ALFA's share capital,  on today's
date held by ANTONIO  MIRANDA,  the sale and  purchase  of which is the  subject
matter of the Promissory Agreement, and deposited under the terms and conditions
of the present Escrow Agreement;

2. Alfa:

     "PETROLEO  MECANICA  ALFA,  SA.", a stock company with the share capital of
PTE  300,000,000$00,  collective body number 500 216 738,  registered before the
Commercial  Registry of Guimaraes under number 1504, with head offices at Brito,
Guimaraes, Portugal;

3.   Purchaser:

     AMTROL or any company,  directly or indirectly,  fully controlled by AMTROL
to whom this assigns the contractual position it has in the Promissory Agreement
or it may have in the Final Agreement;

4. Final Agreement:

     the  definitive  agreement of sale and purchase of the Shares to be entered
into by ANTONIO  MIRANDA  and AMTROL or by a company,  directly  or  indirectly,
fully  controlled  by this latter and for such purpose  indicated  until 10 days
before Date of Completion;

5. Escrow Agreement:

     the present escrow agreement;

6. Promissory Agreement

     the Promissory Agreement of purchase and sale of the Shares entered into by
ANTONIO MIRANDA and AMTROL on the 30th June 1997;

7. Completion Date:

     the date of signature of the Agreement on the 22nd December 1997;

8. Indemnification Escrowed Amount:

     the escrowed amount  corresponding  to the damages claimed by the PURCHASER
and not  accepted  by the  VENDOR up to the limit of one  million  Dollars  (USD
1,000,000), together with all respective earnings;

9. Final Deposit

     the deposit of five millions and five hundred thousand Dollars, reduced by,
as the case may be, the amount of the Indemnification Escrowed Amount, and/or by
the quantified  amount of damages claimed by AMTROL,  until Completion Date, and
which have been accepted by ANTONIO MIRANDA,  through written document signed by
both;

10. Initial Escrowed Amount:

     the escrowed  deposit,  subject to the conditions of this Escrow Agreement,
of fourteen  millions  Dollars (USD  14,000,000),  made by AMTROL on the 30th of
June 1997 with the Escrow Bank,  together with all its respective  earnings,  or
reduced  to  four  millions  Dollars  (USD  4,000,000),  together  with  all its
respective  earnings in accordance  with the terms of number four of clause 7 of
this Escrow Agreement;

11. Business Day

     any day,  except for Saturday or Sunday or a day where the banks located in
Rhode Island or Porto may be closed or are not legally authorised to be opened;

12. Dollar:

     the legal currency of the United States of America;

13. Taxation:

     all  forms of  taxation,  duties,  imposts,  surcharges,  levies  and rates
imposed in Portugal,  including without  limitation,  imposto sobre o rendimento
das pessoas colectivas (IRC),  imposto sobre o valor acrescentado (IVA), imposto
de selo,  contribuicoes para a seguranca social payments to the social security,
contribuicao autarquica, imposto sobre as sucessoes e doacoes, imposto municipal
de SISA, taxas  alfandegarias,  or other similar  contributions and, in general,
any interest,  penalty or fine in connection therewith and cognate words such as
"Tax", "Taxes", "Taxation liability" and similar shall be similarly defined;

14. Vendor:

     ANTONIO MIRANDA;

                                    CLAUSE 1
                                   Escrow Bank

     1.  ANTONIO  MIRANDA  and AMTROL  hereby  designate  the Escrow Bank as the
escrow  entity for the  Shares,  Initial  Escrowed  Amount  and  Indemnification
Escrowed  Amount,  and the Escrow Bank hereby agrees to serve in accordance with
the terms, conditions and provisions of this Escrow Agreement.

     2. At any time prior to Completion  Date, upon request of ANTONIO  MIRANDA,
the Escrow  Bank shall  provide  him with proof of  exclusive  ownership  of the
Shares for the purposes of participation in ALFA's general meetings.

                                    CLAUSE 2
                             Initial Escrowed Amount

     The PURCHASER has deposited,  on today's date, the Initial  Escrowed Amount
with the Escrowed Bank, who confirms to have received it and which it shall only
deliver under the terms and conditions established in this Escrow Agreement.

                                    CLAUSE 3
                              Escrow for the Shares

     The VENDOR has deposited, on today's date, the Shares with the Escrow Bank,
who  confirms to have  received  them and who shall only  deliver them under the
terms and conditions established in this Escrow Agreement.

                                    CLAUSE 4
                                 ESCROW ACCOUNTS

     1. The Initial  Escrowed  Amount and the  Indemnification  Escrowed  Amount
shall be  deposited in accounts,  one for each amount,  for this purpose  opened
with the Escrow Bank, for the benefit of the VENDOR and the PURCHASER;

     2. The Shares shall be  deposited in a securities  account for this purpose
opened with the Escrow Bank, for the benefit of the VENDOR and the PURCHASER.

     3. The Final Deposit shall be delivered with the Escrow Bank, on Completion
Date or within  the next five  Business  Days or before  Completion  Date if the
VENDOR's dies.


                                    CLAUSE 5
                                   Investments

     1. The Escrow Bank shall  remunerate  the Initial  Escrowed  Amount and the
Indemnification Escrowed Amount, at the yearly net rate of 5.375%.

     2.  Notwithstanding the above mentioned,  if the Initial Escrowed Amount is
delivered  to the VENDOR,  he shall be entitled to receive  accrued net interest
calculated  upon a minimum  yearly rate of 7%,  being the  difference  for less,
which may eventually exist between this rate and the net rate obtained under the
terms of the previous number, incurred into by the PURCHASER.

                                    CLAUSE 6
                              Deliver of the Shares

     1. The Escrow Bank, shall deliver the Shares to the PURCHASER:

     a) upon receipt of the certificate  signed by the VENDOR and the PURCHASER,
in the form of Annex I attached hereto,  together with a copy of the original of
the Final Agreement, also signed by both;

     b) upon  delivery to the Escrow  Bank,  within the five  Business Day after
Completion  Date,  of the Final  Deposit  and upon  receipt of the  certificate,
signed by the PURCHASER,  in the form of Annex II attached hereto, together with
the original of the Final Agreement signed by AMTROL,  the contents of which are
equal to the draft attached hereto in the form of Annex III;

     c) upon receipt of the certificate, signed by the PURCHASER, in the form of
Annex IV and together with death certificate of the VENDOR,  and delivery of the
Final Deposit with the Escrow Bank;

     2. The Escrow Bank, shall deliver the Shares to the VENDOR, or to his heirs
if he dies,  from the fifth Business Day,  exclusive,  counting from  Completion
Date, upon receipt of the  certificate,  signed by the former or the latter,  in
the form of Annex V or VI,  as the case may be, if any of the  situations  above
mentioned in  paragraphs  a), b) and c) of the previous  number  occurs does not
occur.

     3. The Final  Deposit  shall be  reduced  by the  quantified  amount of the
damages claimed by the PURCHASER until Completion Date, which have been accepted
by the  VENDOR,  in a  written  document  signed by both,  given  the  PURCHASER
delivers  with the Escrow  Bank the  certificate  in form of Annex VII  attached
hereto, together with the original of the document referred to in this number.


                                    CLAUSE 7
        Delivery of the Initial Escrowed Amount and of the Final Deposit

     1. The Escrow Bank shall deliver the Initial  Escrowed Amount and the Final
Deposit to the VENDOR or to his heirs,  as the case may be, by wire transfer for
the account number  50008.9 opened with the Escrow Bank under ANTONIO  MIRANDA's
name or his heirs,  if he dies, or by cheque issued by the Escrow Bank under the
VENDOR's  name if he so  requests  the  Escrow  Bank in  writing,  if any of the
situations  foreseen  in number one of clause 6 occurs  and upon  receipt of the
certificates and documents also thereof foreseen.

     2. The  Escrow  Bank  shall  deliver  the  Initial  Escrowed  Amount to the
PURCHASER  if the  situation  referred to in number two of the  previous  clause
occurs and upon receipt of the  certificate  in the form of Annex VIII  attached
hereto, with observance of number four of this clause.

     3. If, under the terms of number two of the  previous  clause and until the
twentieth  Business Day,  inclusive,  after  Completion Date, the VENDOR has not
asked the Escrow  Bank for the  delivery of the Shares,  the Escrow  Bank,  upon
receipt of the certificate in the form of Annex IX attached hereto, given by the
PURCHASER,  shall deliver the Initial  Escrowed  Amount to the  PURCHASER,  with
observance, notwithstanding, of number four of this clause.

     4. If the VENDOR has,  within the term referred to in the previous  number,
presented  to the  Escrow  Bank a notice of  arbitration  in the form of Annex X
attached hereto, the Escrow Bank, upon receipt of the certificate in the form of
Annex IX attached  hereto,  shall  deliver to the  PURCHASER  only ten  millions
Dollars  (USD  10,000,000)  from the  Initial  Escrowed  Amount,  which shall be
reduced to four millions Dollars (USD 4,000,000).

     5. If the VENDOR does not submit within fifty Business Days,  counting from
Completion  Date,  before the arbitral  tribunal the claim  communicated  to the
Escrow Bank  through the  certificate  in form of Annex X attached  hereto,  the
Escrow Bank shall  deliver to the  PURCHASER  the Initial  Escrowed  Amount upon
receipt of the certificate in form of Annex XI attached hereto,  together with a
certified  copy stating  there is no  arbitration  instance  pending  before the
Arbitral Centre identified in clause 19.

                                    CLAUSE 8
                              Arbitration Decision

     Apart from the  situations  foreseen  in  clauses 6 and 7, the Escrow  Bank
shall only deliver the Shares and the Initial Escrowed Amount to the VENDOR, his
heirs  and/or  to  the  PURCHASER,  as the  case  may  be,  in  compliance  with
arbitration decisions,  upon receipt of the certificate in the form of Annex XII
or XIII, as may be applicable, signed by who presents it.


                                    CLAUSE 9
                                  Common Accord

     The Escrow Bank shall,  always and at any time, deliver both the Shares and
the whole or part of the Initial Escrowed Amount to the VENDOR, his heirs and/or
to the  PURCHASER,  as the case  may be,  under  the  terms  established  by the
certificate in the form of Annex XIV or XV, as may be applicable, signed by both
the VENDOR or his heirs and the PURCHASER.

                                    CLAUSE 10
                            Refusal of authorisation

     If the competent  authorities on competition law refuse  authorisation  for
the transfer of the Shares from the VENDOR to the PURCHASER,  either of them may
request the Escrow Bank the release of the Shares to the VENDOR and the delivery
of the Initial  Escrowed  Amount to the  PURCHASER,  upon receipt in the form of
Annex XVI or XVII hereto  attached,  as the case may be, together with a copy of
such decision certified by the referred to authorities.

                                    CLAUSE 11
                 Deliver of the Indemnification Escrowed Amount

     The  whole  or  parts  of the  Indemnification  Escrowed  Amount  shall  be
delivered by the Escrow Bank:

     a) to the VENDOR and/or the PURCHASER under the terms and conditions, which
they have both defined by common accord,  upon receipt of the certificate,  made
and signed by both, in the form of Annexes XVIII or XIX, as may be applicable;

     b) to the VENDOR,  his heirs or to the  PURCHASER,  by means of arbitration
decision,  under the terms by such decision  defined and to the extent permitted
by the existing amount of the  Indemnification  Escrowed Amount, upon receipt of
the certificate in the form of Annex XX or XXI, as may be applicable;

                                    CLAUSE 12
                      Extinction of the Escrowed Agreement

     This  Escrow  Agreement  extinguishes,  releasing  the Escrow Bank from all
duties and obligations hereby established,  upon delivery of the totality of the
funds in the accounts of Initial  Escrowed Amount and  Indemnification  Escrowed
Amount and upon delivery of the Shares.

                                    CLAUSE 13
                       Responsibilities of the Escrow Bank

     1. The Escrow Bank shall have no duties or  responsibilities  except  those
expressly set forth herein.

     2. The Escrow  Bank shall have no  responsibility  for the  validity of any
agreements  referred to in this Escrow Agreement,  or for the performance of any
such  agreements  by any party thereto or for the  interpretation  of any of the
provisions of any of such agreements.

     3. The Escrow Bank may only be held liable for bad-faith, wilful misconduct
or gross  negligence  on its part,  not being held  responsible  for  actions or
omissions  in  reliance  on any  certificate,  instruction,  direction  or other
instrument  whatsoever  received by the Escrow Bank in writing under this Escrow
Agreement,  not only as to its due execution and the validity and  effectiveness
of its  provisions,  but also as to the truth and  accuracy  of any  information
therein  contained,  which the Escrow Bank in good faith  believes to be genuine
and to have been  signed and  presented  by a proper  person or persons or their
counsel.

     4.  Even if any  controversy  arises  between  one or  more of the  parties
hereto,  or between any of the parties  hereto and any third  person not a party
hereto,  as to whether or not to whom the Escrow Bank shall deliver the cash, or
a part thereof, of the Initial Escrowed Amount and/or  Indemnification  Escrowed
Amount or the  Shares,  or as to any matter  arising  out of or relating to this
Escrow  Agreement,  the Escrow  Bank shall not be  required  to  determine  such
dispute,  but it shall  rigorously  observe  the  instructions  it  receives  in
accordance with this Escrow  Agreement,  not being, in any case, held liable for
such observance.

     5.  The  Escrow  Bank  may  rely  on any  notice,  instruction,  direction,
certificate,  statement,  request,  consent,  confirmation,  agreement  or other
instrument in writing which it believes to be genuine and to have been signed or
presented  by  a  proper  person  or  persons,  having,  in  what  respects  the
communications  foreseen  in  clauses  6 to 11 of  this  Escrow  Agreement,  the
signature  of the VENDOR or his heirs,  if duly  qualified  as such by  notarial
deed,  as  well  as the  signature  and  sufficiency  of  powers  of the  proper
representative of the PURCHASER, be legalised by notary or by the Escrow Bank.

     6. This Escrow  Agreement set forth the entire  agreement  among the VENDOR
and the PURCHASER and the Escrow Bank with respect to the escrow  accounts,  the
distribution of the cash held therein and the release of the Shares.

     7.  Notwithstanding  any  provision to the contrary  contained in any other
agreement  between  any of the  parties  hereto,  the Escrow  Bank shall have no
interest  in the  escrowed  accounts or in the  Shares,  being its  intervention
limited as escrow holder, having only possession of them under such terms.

     8. The Escrow Bank shall have no duty to ascertain  the contents of, or the
compliance of ANTONIO MIRANDA and/or AMTROL with the Promissory Agreement or the
Final Agreement.

                                    CLAUSE 14
                                Fees and Expenses

     1. For the  services  rendered by the Escrow Bank in the  execution of this
Escrow  Agreement,  this Escrow Bank shall charge AMTROL a fee of PTE 500,000$00
(five hundred thousand Portuguese Escudos), plus VAT at the applicable rate.

     2. The VENDOR and the  PURCHASER  hereby  undertake to make the transfer of
the Shares through the Escrow Bank, or through whom this latter indicates, being
fixed the  broker's  fees as PTE  1,500,000$00  (one  million  and five  hundred
thousand Portuguese escudos), which shall be incurred into by the PURCHASER.

                                    CLAUSE 15
                                     Notices

     1. All  communications  required pursuant to this Escrow Agreement shall be
addressed to the Escrow Bank, ANTONIO MIRANDA and AMTROL, as follows:

    n   If to the Escrow Bank:
    BPI - Banco Portugues do Investimento, SA.
    Rua Tenente Valadim, n 284
    4100 Porto
    Portugal
    Att.: Mr. Mario Pereira Pinto
    Fax: 00-351-2-6000 856

    n   If to ANTONIO MIRANDA:
    Mr. Antonio Brandao Miranda,
    c/o Calves, SA.,
    Rua de Gondarem, nr.956,
    4150 Porto,
    Portugal;
    Fax: 00-351-2-617 7282

    with copy to:
    Mr. Joao Vieira de Castro,
    Largo do Adro, nr. 9,
    4050 Porto,
    Portugal;
    Fax: 00-351-2-609 4688

     n    If to AMTROL:
     AMTROL Inc.,
     1400 Division Road,
     West Warwick, RI 02893
     U.S.A.
     Att. of Mr. Edward J. Cooney,
     Fax: 00-1-401-884-7816

     with copies to:
     Mr. Jose de Freitas,
     Av. da Boavista, 1383 - 2,
     4100 Porto,
     Portugal,
     Fax: 00-351-2-6001848

and

     Ms. Margaret D. Farrell, Esq.
     Hinckley, Allen & Snyder
     1500 Fleet Center,
     Providence, R I 02903,
     U.S.A.
     Fax: 001-401-277-9600

     2. Any notice or other communication required or permitted under any of the
provisions of this Escrow Agreement shall be sufficiently  given if delivered in
person or sent by telecopy or by registered  mail with receipt,  sent by express
mail,  addressed to the  respective  address of the parties  hereto as set forth
above and to such other  address  or number of  telecopy  as shall be  hereafter
furnished in writing by any such party.

     3.  All  notices  or other  communications  shall be  deemed  to have  been
received on the date of delivery,  unless if sent by telecopy, in which case, if
received  on any  day  which  is not a  Business  Day or  after  working  hours,
considered as between 8 a.m. and 5 p.m. of any Business Day,  shall be deemed to
have been received in the next Business Day.


                                    CLAUSE 16
                               Parties in Interest

     The rights and  obligations  arising  from this Escrow  Agreement  shall be
binding  upon the parties  hereto and their  respective  heirs,  successors  and
assigns,  including without  limitation any private or collective entity, who or
which assumes to this Escrow  Agreement,  Promissory  Agreement or Agreement the
contractual  position  of  ANTONIO  MIRANDA  or  AMTROL,  who or which  shall be
immediately  bound by the  rights  and  obligations  of the  substituted  party,
arising from this Escrow Agreement.


                                    CLAUSE 17
                                    Captions

     The Section Captions used herein are for reference  purposes only and shall
not in any way affect the meaning or interpretation of this Escrow Agreement.


                                    CLAUSE 18
                       Indemnification of the Escrow Bank

     1. The VENDOR and the PURCHASER  shall  indemnify the Escrow Bank,  for the
damages they cause to it for the defective fulfilment of this Escrow Agreement.

     2. On its  turn,  the  Escrow  Bank  shall  indemnify  the  VENDOR  and the
PURCHASER for the damages it causes to them for the defective fulfilment of this
Escrow Agreement.

     3. The  obligations of the PURCHASER  herein arising from shall survive the
renounce ou  substitution  of the Escrow Bank and to any form of  termination of
this Agreement,  including without limitation any termination under the terms of
bankruptcy law.

                                    CLAUSE 19
                               Dispute Resolution

     All disputes arising out of this Promissory Agreement shall be definitively
decided  in  accordance  with  Regulamento  do  Tribunal  Arbitral  do Centro de
Arbitragem  Comercial da Camara de Comercio e Industria  Portuguesa / Associacao
Comercial  de Lisboa e da Camara de Comercio e Industria  do Porto /  Associacao
Comercial do Porto,  by one or more  arbitrators in accordance  with such Rules.
The Arbitration shall take place in Porto, Portugal.

                                    CLAUSE 20
                                  Governing Law

     This Escrow Agreement shall be construed and interpreted in accordance with
and governed by the laws of Portugal.


                                    CLAUSE 21
                                  Counterparts

     This  Agreement  shall  be  executed  in  three  counterparts,  each of one
constituting an original.

                                                        Porto, 30th of June 1997

ANTONIO BRANDAO MIRANDA


AMTROL Inc.


BPI - BANCO PORTUGUES DO INVESTIMENTO, SA.







                                ESCROW AGREEMENT


                                     ANNEX I


                        FORM OF JOINT RELEASE CERTIFICATE

     To: Banco  Portugues do  Investimento,  SA., Escrow Bank in accordance with
the Escrow Agreement  referred to below Address:  Rua Tenente  Valadim,  nr.284,
4100 Porto Portugal Att.: Mr. Mario Pereira Pinto Ref.: Escrow Agreement,  dated
as of 30th June 1997, by and among the Escrow Bank,  ANTONIO  MIRANDA and AMTROL
(the "Escrow Agreement")


     Ladies and Gentlemen:

     Pursuant to number one,  paragraph a) of clause 6 of the Escrow  Agreement,
the undersigned  (the VENDOR or Mr._____ a duly authorized  representative)  and
(Mr.  _________ a duly authorized  officer of the PURCHASER) hereby certify that
attached  hereto is a true and correct copy of the Final Agreement and authorise
the Escrow Bank to deliver the whole of the Initial  Escrow Amount and the Final
Deposit to the VENDOR and to deliver the Shares to the PURCHASER.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ___ of _______.


                                                     Very truly yours,

THE VENDOR

THE PURCHASER






                                ESCROW AGREEMENT

                                    ANNEX II

                          PURCHASER RELEASE CERTIFICATE

     To: Banco  Portugues do  Investimento,  SA., Escrow Bank in accordance with
the Escrow Agreement  referred to below 

     Address:  Rua Tenente Valadim,  nr.284, 
               4100 Porto Portugal 
Att.: Mr. Mario Pereira Pinto 

     Ref.:  Escrow  Agreement,  , dated as of 30th June  1997,  by and among the
Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to number one,  paragraph b) of clause 6 of the Escrow  Agreement,
the undersigned,  Mr. _____ a duly authorised  officer of the PURCHASER,  hereby
certifies to the Escrow Bank that attached  hereto is a true and correct copy of
the Final  Agreement,  duly executed by an authorised  officer of the PURCHASER,
and that,  because  it has  delivered  with the Escrow  Bank the Final  Deposit,
requests  the  Shares,  deposited  in the  account of  deposit  of  Shares,  are
immediately  released to the  PURCHASER  and that the Initial  Escrow Amount and
Final Deposit are put at the VENDOR's disposal.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ___ of _______.


                                                     Very truly yours,

THE PURCHASER






                                ESCROW AGREEMENT


                                    ANNEX III


                  AGREEMENT ON THE SALE AND PURCHASE OF SHARES


     ANTONIO  BRANDAO  MIRANDA  (hereinafter  referred  to as ANTONIO  MIRANDA),
married under the legal separation  regimen,  born at Argivai,  Povoa de Varzim,
resident at Rua do Molhe,  nr.27,  Porto,  Portugal 

and 

     AMTROL Inc. or a company fully controlled by it (hereinafter referred to as
AMTROL),  with head offices at 1400 Division Road,  West Warwick,  Rhode Island,
United States of America, hereby represented by its president John P. Cashman,


WHEREAS:

     ANTONIO  MIRANDA  is the only owner of the  shares  representing  the share
capital of "PETROLEO MECANICA ALFA, SA." (hereinafter referred to as ALFA), with
head offices at Brito, Guimaraes;

     AMTROL  wants to  purchase  and ANTONIO  MIRANDA  wants to sell the 300,000
shares representing the share capital of ALFA;



     THE ABOVE IDENTIFIED PARTIES AGREE TO ENTER INTO THIS AGREEMENT OF SALE AND
PURCHASE OF SHARES, WHICH SHALL BE GOVERNED BY THE FOLLOWING PROVISIONS:

                                    CLAUSE 1
                                   Definitions

     In this  agreement,  the  following  words and  expressions  shall have the
following meaning:

1.1.  SHARES:

     the totality of the shares  representing  the issued share capital of ALFA,
on today's date held by ANTONIO MIRANDA and which are the subject matter of this
Agreement;

1.2.  DOLLAR:
    
     the legal currency of the United States of America;

1.3.  ALFA or COMPANY:
    
     "PETROLEO  MECANICA  ALFA,  SA.", a stock company with the share capital of
PTE  300,000,000$00,  collective body number 500 216 738,  registered before the
Commercial  Registry of Guimaraes under number 1504, with head offices at Brito,
Guimaraes, Portugal;

                                    CLAUSE 2
                                Sale and purchase

     1. ANTONIO MIRANDA sells and AMTROL, or the company fully controlled by it,
indicated until 10 days before today's date,  purchases all the Shares, with the
nominal value of PTE 1,000,000$00  each,  representing the totality of the share
capital of ALFA.

     2. All  patrimonial  rights  relating  to the  Shares or to the  quality of
shareholder, verified from 1st January 1997, shall be transferred to AMTROL.

     3.  The  patrimonial  rights  mentioned  in the  previous  paragraph  shall
include,  namely and without  limitation:  

     a) right to profits or dividends;

     b) right to shareholder's loans to ALFA;

     c) right to subscribe increases in ALFA's issued share capital;

     d) right to supplementary capital / equity;


                                    CLAUSE 3
                                      Price

     The  price for the sale and  purchase  of the  Shares  agreed  between  the
parties is of USD  25,500,000  (twenty five  millions and five hundred  thousand
Dollars),  which AMTROL has already paid and which ANTONIO  MIRANDA hereby gives
his acquittal for.


                                    CLAUSE 4
                          Intellectual property rights

     1. ANTONIO MIRANDA grants AMTROL or ALFA, by the former's  (AMTROL) choice,
as the case may be, the right to use the word COMANOR as a non-registered  trade
mark.

     2. ANTONIO  MIRANDA  further  undertakes  not to prevent or  difficult  the
registry of the trade mark COMANOR, under the name of AMTROL or ALFA, giving his
express authorisation, if need be, for such purposes.


                                    CLAUSE 5
                                 Non-competition

     ANTONIO  MIRANDA  undertakes  not to  exercise,  for a term of  five  years
counting from today,  any activity which directly or indirectly may compete with
the  activity  carried  out by the  Company,  which  is the  manufacture  and/or
reparation  or  requalification  (refurbishment?)  of reusable or  dischargeable
containers, used for G.P.L., for refrigerating gases or for technical gases.


                                    CLAUSE 6
                                Further assurance

     ANTONIO MIRANDA shall  co-operate with AMTROL and shall sign and deliver to
AMTROL all documents which may be necessary for the transfer of the Shares.


                                    CLAUSE 7
                         Applicable law and arbitration

     1. This agreement is governed by Portuguese law.

     2. All disputes  arising out of this Final  Agreement shall be definitively
decided  in  accordance  with  Regulamento  do  Tribunal  Arbitral  do Centro de
Arbitragem  Comercial da Camara de Comercio e Industria  Portuguesa / Associacao
Comercial  de Lisboa e da Camara de Comercio e Industria  do Porto /  Associacao
Comercial do Porto,  by one or more  arbitrators in accordance  with such Rules.
The Arbitration shall take place in Porto and the language shall be Portuguese.


                                    CLAUSE 8
                                     Notices

     1. Any notice or  communication  given  under the terms of this  Promissory
Agreement shall be in writing and shall be sufficiently given if addressed to:

     a) AMTROL Inc,  1400 Division  Road,  West  Warwick,  Rhode Island,  United
States of America,  to the  attention of Mr. Edward  Cooney,  with copies to Mr.
Jose de  Freitas,  Av. da  Boavista,  1383 - 2, 4100  Porto,  Portugal,  and Ms.
Margaret  Farrell,  1500 Fleet Center,  Providence,  Rhode Island 02903,  United
Sates of America;

     b) ANTONIO BRANDAO MIRANDA, c/o Calves, SA., Rua de Gondarem,  nr.956, 4150
Porto,  Portugal,  with copies to Mr. Joao Vieira de Castro,  Largo do Adro,  9,
4050 Porto, Portugal;


                                    CLAUSE 9
                                  Counterparts

     This Promissory  Agreement is executed in two counterparts each of which is
an original.



Porto, ____ of ________






                                ESCROW AGREEMENT


                                    ANNEX IV

                          PURCHASER RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284, 
              4100 Porto Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to number one,  paragraph c) of clause 6 of the Escrow  Agreement,
the  undersigned Mr. ______ a duly  authorized  officer of the PURCHASER  hereby
certifies  to the  Escrow  Bank  that  attached  hereto  is the  VENDOR's  death
certificate and because it has delivered with the Escrow Bank the Final Deposit,
requests  that the Shares,  deposited  in the account of deposit of Shares,  are
immediately  released to the  PURCHASER,  and that the Initial Escrow Amount and
Final Deposit are put at the VENDOR's heirs disposal.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE PURCHASER






                                ESCROW AGREEMENT

                                     ANNEX V

                           VENDOR RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284, 
              4100 Porto 
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to number two of clause 6 of the Escrow Agreement, the undersigned
(the VENDOR or Mr. _____ his duly authorized representative) requests the Escrow
Bank the release of the Shares,  deposited in the account for shares,  given the
fact none of the  situations  foreseen in paragraphs a), b) and c) of number one
of clause 6 of the Escrow Agreement has, until today's date,  occurred and given
the fact more than five Business Days have already passed since Completion Date.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE VENDOR /  his duly authorized representative







                                ESCROW AGREEMENT

                                    ANNEX VI

                       VENDOR's HEIRS RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to number two of clause 6 of the Escrow Agreement, the undersigned
(VENDOR's  heirs) hereby  certify(ies) to the Escrow Bank that they (he/she) are
(is)  legitimated  as heir(s)  through the notarial  deed of  legitimacy  hereto
attached,  and  request(s)  the Escrow  Bank to deliver  to them  (him/her)  the
Shares, deposited in the escrow account of deposit of Shares given the fact none
of the situations foreseen in paragraphs a), b) and c) of number one of clause 6
has,  until  today's  date,  occurred and given the fact more than five Business
Days have already passed since Completion Date.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE VENDOR's HEIR(S)





                                ESCROW AGREEMENT

                                    ANNEX VII

                    NOTICE FOR REDUCTION OF THE FINAL DEPOSIT

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284, 
              4100 Porto 
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")


     Ladies and Gentlemen:

     Pursuant  to  number  three  of  clause  6 of  the  Escrow  Agreement,  the
undersigned  Mr.  _____  a duly  authorized  officer  of the  PURCHASER,  hereby
certifies the Escrow Bank that, in accordance  with the document  signed both by
the  VENDOR and  PURCHASER,  the Final  Deposit  was  reduced  for the amount of
_________ by reduction of the amount of ____________

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE PURCHASER




                                ESCROW AGREEMENT

                                   ANNEX VIII

                          PURCHASER RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to number two of clause 7 of the Escrow Agreement, the undersigned
Mr.  _________ a duly authorised  officer of the PURCHASER,  requests the Escrow
Bank the delivery of the Initial  Escrowed  Amount given the fact the  situation
foreseen in number two of clause 6 of the Escrow Agreement has occurred.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________

                                                     Very truly yours,


THE PURCHASER





                                ESCROW AGREEMENT

                                    ANNEX IX

                          PURCHASER RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant  to  number  three  of  clause  7 of  the  Escrow  Agreement,  the
undersigned Mr. _________ a duly authorized  officer of the PURCHASER,  requests
the Escrow Bank the delivery of the Initial  Escrowed  Amount given the fact the
VENDOR has not,  until today's  date,  requested the Escrow Bank the delivery of
the  Shares,  having  already  passed  more  than  twenty  Business  Days  since
Completion Date.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE PURCHASER








                                ESCROW AGREEMENT

                                     ANNEX X

                ARBITRATION NOTICE DUE TO FAULT OF THE PURCHASER


     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant  to  number  four  of  clause  7  of  the  Escrow  Agreement,  the
undersigned  (VENDOR or Mr.  ________ a duly  authorised  representative  of the
VENDOR) or (his heirs, duly legitimated by notarial deed),  hereby certifies the
Escrow Bank of a disputed claim for faulty breach of the Promissory Agreement by
the  PURCHASER and  certifies  that the same is going to be submitted  before an
arbitration tribunal,  within fifty Business Days counting from Completion Date,
in accordance with clause 22 of the Promissory Agreement and that a copy of this
arbitration notice has been delivered to the PURCHASER.


     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE VENDOR/ his legitimate representative/THE VENDOR's HEIR(S)





                                ESCROW AGREEMENT


                                    ANNEX XI

                          PURCHASER RELEASE CERTIFICATE


     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant  to  number  five  of  clause  7  of  the  Escrow  Agreement,  the
undersigned  Mr.  _______ a duly  authorised  representative  of the  PURCHASER,
hereby  requests  the Escrow Bank the delivery of the Initial  Escrowed  Amount,
reduced to four millions of Dollars (USD 4,000,000), given the fact that, having
passed more than fifty Business Days counting from  Completion  Date, the VENDOR
has not submitted to the arbitral tribunal,  until today's date, the claim which
he has  previously  communicated  to the Escrow Bank,  under the terms of number
four of clause 7, as it is certified by the certified copy hereto attached.


     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE PURCHASER





                                ESCROW AGREEMENT



                                     ANNEX XII

                     NOTICE OF TRIBUNAL ARBITRAL's DECISION


     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to clause 8 of the Escrow  Agreement,  the undersigned (the VENDOR
or Mr.  ________  a duly  authorized  representative)  or  (Mr.  _______  a duly
authorized  officer of the PURCHASER),  hereby  certifies the Escrow Bank of the
decision of the arbitral  tribunal  attached hereto and, in accordance with such
decision,  requests  the  delivery  of the Shares  and/or the  Initial  Escrowed
Amount, under the specific terms thereto established.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE VENDOR / Duly authorised representative of the VENDOR / THE PURCHASER




                                ESCROW AGREEMENT


                                   ANNEX XIII

                     NOTICE OF TRIBUNAL ARBITRAL's DECISION


     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow Agreement,  , dated as of 30th June 1997,  entered into among
the Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to clause 8 of the Escrow Agreement, the undersigned (the VENDOR's
heir(s)),  hereby  certifies(y)  he/she(they)  is (are)  legitimated as heir(s),
through the notarial deed of legitimacy  hereto attached and hereby  notifies(y)
the Escrow Bank of the decision of the arbitral tribunal attached hereto and, in
accordance  with such  decision,  requests  (request) the delivery of the Shares
and/or  the  Initial   Escrowed   Amount,   under  the  specific  terms  thereto
established.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE VENDOR's HEIR(S)








                                ESCROW AGREEMENT



                                     ANNEX XIV

                        FORM OF JOINT RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow  Agreement,  , dated as of 30th June  1997,  by and among the
Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to clause 9 of the Escrow  Agreement,  the undersigned (the VENDOR
or Mr.  _______ a duly  authorized  representative)  and (Mr.  _________  a duly
authorized  officer of the PURCHASER)  hereby request the Escrow Bank, by common
accord,  to release  the Shares  and/or  the (or part of the)  Initial  Escrowed
Amount to the  VENDOR  or to  release  the  Shares  and/or  the (or part of the)
Initial Escrowed Amount to the PURCHASER

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________



                                                     Very truly yours,

THE VENDOR / His duly representative

THE PURCHASER





                                ESCROW AGREEMENT

                                    ANNEX XV

                        FORM OF JOINT RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow  Agreement,  , dated as of 30th June  1997,  by and among the
Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to clause 9 of the Escrow Agreement, the undersigned (the VENDOR's
heir(s)), who certifies(y) to be legitimated as heir(s) through notarial deed of
legitimacy hereto attached,  and (Mr. ________ a duly authorized  officer of the
PURCHASER),  hereby  request the Escrow Bank, by common  accord,  to release the
Shares  and/or  the (or part of the)  Initial  Escrowed  Amount to the  VENDOR's
heir(s) or to release the Shares  and/or the (or part of the)  Initial  Escrowed
Amount to the PURCHASER.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE VENDOR's HEIR(S)

THE PURCHASER





                                ESCROW AGREEMENT


                                    ANNEX XVI

                          PURCHASER RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow  Agreement,  , dated as of 30th June  1997,  by and among the
Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant  to  clause  10 of  the  Escrow  Agreement,  the  undersigned  Mr.
__________  a duly  authorised  officer of the  PURCHASER,  hereby  requests the
Escrow Bank to release the Initial  Escrowed  Amount to the PURCHASER and to put
the Shares at the VENDOR's disposal,  because the transfer of the Shares was not
authorised by the competent  authorities on competition law, as certified in the
certificate hereto attached,.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________



                                                     Very truly yours,


THE PURCHASER





                                ESCROW AGREEMENT

                                   ANNEX XVII

                           VENDOR RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow  Agreement,  , dated as of 30th June  1997,  by and among the
Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant to clause 10 of the Escrow Agreement,  the undersigned (the VENDOR
or Mr. ________ a duly authorized representative), or (the VENDOR's heir(s), who
certifies(y)  to be legitimated as heir(s)  through  notarial deed of legitimacy
hereto  attached),  hereby  requests  the Escrow  Bank to release  the Shares to
him/her/them  and that the  Initial  Escrowed  Amount is put at the  PURCHASER's
disposal, because the transfer of the Shares was not authorised by the competent
authorities on competition law, as certified in the certificate hereto attached.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________



                                                     Very truly yours,

THE VENDOR/ his duly representative/THE VENDOR's HEIR(S)





                                ESCROW AGREEMENT


                                   ANNEX XVIII

                            JOINT RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow  Agreement,  , dated as of 30th June  1997,  by and among the
Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant  to  paragraph  a) of  clause  11 of  the  Escrow  Agreement,  the
undersigned  (the VENDOR or Mr. ________ a duly authorized  representative)  and
(Mr.  ________ a duly  authorized  officer of the PURCHASER)  hereby request the
Escrow Bank, by common accord,  to release the (or part of the)  Indemnification
Escrowed Amount to the VENDOR or to release the (or part of the) Indemnification
Escrowed Amount to the PURCHASER.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________


                                                     Very truly yours,

THE VENDOR/his duly representative



THE PURCHASER





                                ESCROW AGREEMENT

                                    ANNEX XIX

                        FORM OF JOINT RELEASE CERTIFICATE

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow  Agreement,  , dated as of 30th June  1997,  by and among the
Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant  to  paragraph  a) of  clause  11 of  the  Escrow  Agreement,  the
undersigned  (the VENDOR's  heir(s)),  who  certifies(y)  to be  legitimated  as
heir(s) through notarial deed of legitimacy hereto attached, and (Mr. ________ a
duly authorized  officer of the  PURCHASER),  hereby request the Escrow Bank, by
common accord, to release the (or part of the)  Indemnification  Escrowed Amount
to the  VENDOR's  heir(s)  or to  release  the (or part of the)  Indemnification
Escrowed Amount to the PURCHASER.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________

                                                     Very truly yours,

THE VENDOR's HEIR(S)



THE PURCHASER



                                ESCROW AGREEMENT

                                    ANNEX XX

                     NOTICE OF ARBITRAL TRIBUNAL's DECISION

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow  Agreement,  , dated as of 30th June  1997,  by and among the
Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant  to  paragraph  b) of  clause  11 of  the  Escrow  Agreement,  the
undersigned (the VENDOR or Mr. ________ a duly authorized  representative)  (Mr.
________ a duly authorized officer of the PURCHASER) hereby certifies the Escrow
Bank of the decision of the arbitral tribunal attached hereto and, in accordance
with  such   decision,   requests   the   delivery  of  the  (or  part  of  the)
Indemnification Escrowed Amount, under the specific terms thereto established.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________

                                                     Very truly yours,

THE VENDOR/Duly authorized representative of the VENDOR/THE PURCHASER




                                ESCROW AGREEMENT

                                    ANNEX XXI

                     NOTICE OF ARBITRAL TRIBUNAL's DECISION

     To: Banco Portugues do Investimento, SA., as Escrow Bank in accordance with
Escrow Agreement referred to below

     Address: Rua Tenente Valadim, nr.284,
              4100 Porto
              Portugal

     Att.: Mr. Mario Pereira Pinto

     Ref.:  Escrow  Agreement,  , dated as of 30th June  1997,  by and among the
Escrow Bank, ANTONIO MIRANDA and AMTROL (the "Escrow Agreement")

     Ladies and Gentlemen:

     Pursuant  to  paragraph  b) of  clause  11 of  the  Escrow  Agreement,  the
undersigned  (the VENDOR's  heir(s)),  who  certifies(y)  to be  legitimated  as
heir(s)  through  notarial  deed  of  legitimacy  hereto  attached,  and  hereby
certifies(y) the Escrow Bank of the decision of the arbitral  tribunal  attached
hereto and, in accordance with such decision, requests (request) the delivery of
the (or part of the)  Indemnification  Escrowed Amount, under the specific terms
thereto established.

     Unless  otherwise  defined  herein,  the terms used  herein  shall have the
respective meanings provided such terms in the Escrow Agreement.


Porto, ____ of __________

                                                     Very truly yours,

THE VENDOR's HEIR(S)

                                    ANNEX II
                           TO THE PROMISSORY AGREEMENT

                  AGREEMENT ON THE SALE AND PURCHASE OF SHARES

     ANTONIO  BRANDAO  MIRANDA  (hereinafter  referred  to as ANTONIO  MIRANDA),
married under the legal separation  regimen,  born at Argivai,  Povoa de Varzim,
resident at Rua do Molhe,  nr.27,  Porto,  Portugal 

and 

     AMTROL Inc. or a company fully controlled by it (hereinafter referred to as
AMTROL),  with head offices at 1400 Division Road,  West Warwick,  Rhode Island,
United States of America, hereby represented by its president John P. Cashman,


WHEREAS:

     ANTONIO  MIRANDA  is the only owner of the  shares  representing  the share
capital of "PETROLEO MECANICA ALFA, SA." (hereinafter referred to as ALFA), with
head offices at Brito, Guimaraes;

     AMTROL  wants to  purchase  and ANTONIO  MIRANDA  wants to sell the 300,000
shares representing the share capital of ALFA;



     THE ABOVE IDENTIFIED PARTIES AGREE TO ENTER INTO THIS AGREEMENT OF SALE AND
PURCHASE OF SHARES, WHICH SHALL BE GOVERNED BY THE FOLLOWING PROVISIONS:

                                    CLAUSE 1
                                   Definitions

     In this  agreement,  the  following  words and  expressions  shall have the
following meaning:

1.1.      SHARES:

     the totality of the shares  representing  the issued share capital of ALFA,
on today's date held by ANTONIO MIRANDA and which are the subject matter of this
Agreement;

1.2.      DOLLAR:

     the legal currency of the United States of America;

1.3.      ALFA or COMPANY:

     "PETROLEO  MECANICA  ALFA,  SA.", a stock company with the share capital of
PTE  300,000,000$00,  collective body number 500 216 738,  registered before the
Commercial  Registry of Guimaraes under number 1504, with head offices at Brito,
Guimaraes, Portugal;


                                    CLAUSE 2
                                Sale and purchase

     1. ANTONIO MIRANDA sells and AMTROL, or the company fully controlled by it,
indicated until 10 days before today's date,  purchases all the Shares, with the
nominal value of PTE 1,000,000$00  each,  representing the totality of the share
capital of ALFA.

     2. All  patrimonial  rights  relating  to the  Shares or to the  quality of
shareholder, verified from 1st January 1997, shall be transferred to AMTROL.

     3.  The  patrimonial  rights  mentioned  in the  previous  paragraph  shall
include,  namely and without  limitation:  

     a) right to profits or dividends;

     b) right to shareholder's loans to ALFA;

     c) right to subscribe increases in ALFA's issued share capital;

     d) right to supplementary capital / equity;


                                    CLAUSE 3
                                      Price

     The  price for the sale and  purchase  of the  Shares  agreed  between  the
parties is of USD  25,500,000  (twenty five  millions and five hundred  thousand
Dollars),  which AMTROL has already paid and which ANTONIO  MIRANDA hereby gives
his acquittal for.


                                    CLAUSE 4
                          Intellectual property rights

     1. ANTONIO MIRANDA grants AMTROL or ALFA, by the former's  (AMTROL) choice,
as the case may be, the right to use the word COMANOR as a non-registered  trade
mark.

     2. ANTONIO  MIRANDA  further  undertakes  not to prevent or  difficult  the
registry of the trade mark COMANOR, under the name of AMTROL or ALFA, giving his
express authorisation, if need be, for such purposes.


                                    CLAUSE 5
                                 Non-competition

     ANTONIO  MIRANDA  undertakes  not to  exercise,  for a term of  five  years
counting from today,  any activity which directly or indirectly may compete with
the  activity  carried  out by the  Company,  which  is the  manufacture  and/or
reparation  or  requalification  (refurbishment?)  of reusable or  dischargeable
containers, used for G.P.L., for refrigerating gases or for technical gases.


                                    CLAUSE 6
                                Further assurance

     ANTONIO MIRANDA shall  co-operate with AMTROL and shall sign and deliver to
AMTROL all documents which may be necessary for the transfer of the Shares.


                                    CLAUSE 7
                         Applicable law and arbitration

     1. This agreement is governed by Portuguese law.

     2. All disputes  arising out of this Final  Agreement shall be definitively
decided  in  accordance  with  Regulamento  do  Tribunal  Arbitral  do Centro de
Arbitragem  Comercial da Camara de Comercio e Industria  Portuguesa / Associacao
Comercial  de Lisboa e da Camara de Comercio e Industria  do Porto /  Associacao
Comercial do Porto,  by one or more  arbitrators in accordance  with such Rules.
The Arbitration shall take place in Porto and the language shall be Portuguese.


                                    CLAUSE 8
                                     Notices

     1. Any notice or  communication  given  under the terms of this  Promissory
Agreement shall be in writing and shall be sufficiently given if addressed to:

     a) AMTROL Inc,  1400 Division  Road,  West  Warwick,  Rhode Island,  United
States of America,  to the  attention of Mr. Edward  Cooney,  with copies to Mr.
Jose de  Freitas,  Av. da  Boavista,  1383 - 2, 4100  Porto,  Portugal,  and Ms.
Margaret  Farrell,  1500 Fleet Center,  Providence,  Rhode Island 02903,  United
Sates of America;

     b) ANTONIO BRANDAO MIRANDA, c/o Calves, SA., Rua de Gondarem,  nr.956, 4150
Porto,  Portugal,  with copies to Mr. Joao Vieira de Castro,  Largo do Adro,  9,
4050 Porto, Portugal;


                                    CLAUSE 9
                                  Counterparts

     This Promissory  Agreement is executed in two counterparts each of which is
an original.



Porto, ____ of ________






               COMPLEMENTARY DOCUMENT TO THE PROMISSORY AGREEMENT


     ANTONIO  BRANDAO  MIRANDA  (hereinafter  referred  to as ANTONIO  MIRANDA),
married,  born at Agivai,  Povoa de  Varzim,  resident  at Rua do Molhe,  nr.27,
Porto, Portugal

and

     AMTROL Inc.  (hereinafter referred to as AMTROL), with head offices at 1400
Division  Road,  West Warwick,  Rhode Island,  United States of America,  hereby
represented  by its attorney Jose Carvalho de Freitas,  whose quality and powers
for this act are proved by power of  attorney,  the  original  of which shall be
attached to ANTONIO MIRANDA's counterpart of the Promissory  Agreement,  being a
copy attached to AMTROL's counterpart.


HAVING REGARD THAT:

     A) All and any definition included and used in the Promissory  Agreement of
sale and purchase of the Shares,  representing  the share capital of ALFA signed
on today's date by the Parties are valid and used in this document;

     B) It is AMTROL's will to take over the management control of ALFA from the
date of signature of the Promissory Agreement;

     C) The Parties do not wish the text of this document be expressly disclosed
in the body of the Promissory Agreement, although forming part of the Promissory
Agreement,  being  its  execution  dependant  upon  it  and  being  all  rights,
obligations,   representations  and  warranties  of  such  Promissory  Agreement
applicable to this document;


THE PARTIES HEREBY AGREE THAT:

     First: AMTROL assumes, from today's date onwards, the control of management
acts of  ALFA,  as if it were  its only and  single  shareholder,  ceasing  this
situation if and when ANTONIO  MIRANDA  withdraws the Shares in accordance  with
clause 7 of the Promissory Agreement.

     Second:  To substitute  ALFA's directors Mr. Manuel Miranda and Mr. Joaquim
Von Hafe,  who have ceased  their  commissions  on today's  date,  AMTROL  shall
indicated Mr. John Cashman and Mr. Edward J. Cooney as ALFA's  directors,  to be
appointed by  "cooptacao" of the remaining  directors or by nomination  during a
general meeting of the Company.

     Third:  The two ceasing  members of ALFA have already been  indemnified  by
ALFA, having AMTROL full knowledge of the amounts of such  indemnification,  and
having given its approval,  given the fact they have renounced their commissions
before the term, in accordance  with the documents  attached to this document in
the form of an annex.

     Fourth: Upon AMTROL's request,  ANTONIO MIRANDA, through deliberation taken
in a general meeting of the Company held on today's date, amended ALFA's by-laws
in order to provide the qualified  majority of 2/3 for the  deliberations of the
board of directors.

     Fifth:  ANTONIO MIRANDA undertakes not to directly or indirectly  interfere
on the Company's  management,  using his best endeavours to ensure the remaining
directors  shall grant AMTROL the effective  control of management  and that the
former  director  Manuel  Miranda gives AMTROL all support and full  information
which may be useful and necessary about and for the Company's  activity  carried
out until 31st December 1997.

     Sixth: In accordance  with the spirit of number five of this  complementary
document, ANTONIO MIRANDA shall do nothing for:

     a) ALFA to dispose  of,  agree to dispose  of,  grant or agree to grant any
option in respect of any  significant  part of its  assets,  which  shall be the
same, in quantity and quality, as the ones existing on 7th May 1997;

     b) ALFA to enter into any individual contract or commitment,  other than in
the normal course of business,  relating to or affecting a  significant  part of
its business or any materially onerous contract or agreement;

     c) ALFA to create,  non within the normal acts necessary to the exercise of
its  activity,  grant,  issue or agree to create,  grant or issue or allow to be
created  or to exist  any  mortgages,  charges,  debentures,  bonds or any other
securities or redeem or agree to redeem any such  securities or give or agree to
give any guarantees or indemnities;

     d) ALFA to borrow any money or agrees to do so except in the normal  course
of business under normal commercial terms;

     e) ALFA to make any capital  commitment,  other than  expenditure on assets
necessary for the ordinary course of business;

     f) ALFA to make any change in the nature of its business, or to discontinue
or cease to operate all or any part of its business;

     g) ALFA to transfer  all or any part of its business or assets to any other
person or entity other than in the ordinary course of business;

     h) ALFA to engage or to dismiss any  employee or to make any  variation  to
the terms and conditions of employment of such employees;

     i) ALFA to make any change to the  accounting  procedures  or principles by
reference to which its accounts are drawn up;

     Seventh: If the Shares cannot be transferred due to a fact not imputable to
ANTONIO MIRANDA, AMTROL undertakes the following:

     a) the  directors  appointed  or  "cooptdados"  under  its  indication,  in
accordance  with the number two of this  document,  shall  immediately  renounce
their respective  commissions,  recognising in the letter of renounce they shall
address to ALFA,  that nothing is owed to them as a consequence  of the exercise
or termination of their commission, both by ALFA or ANTONIO MIRANDA;

     b) if the previous does not occur and the directors are dismissed  during a
shareholders  meeting, that the payment of any compensation they may be entitled
to by virtue of having not completed their  commissions are of AMTROL's full and
exclusive responsibility;

     c) to be liable to pay ALFA any  compensation  for any act, even if lawful,
having  the  result  of  causing  damages  to  ALFA  by  means  of  considerable
depreciation of the Company;

     d) to pay ANTONIO  MIRANDA an amount  equal to the one spent by ALFA in the
payment of the indemnifications referred to in number three of this document;

     Eight: For the purposes stated under paragraph c) of the previous number, a
considerable  depreciation  is deemed to occur  whenever the damage subject to a
single  claim is for or  exceeds  the  amount of PTE  10,000,000  (ten  millions
Portuguese escudos) or if several damages of lower amounts, considered together,
are equal to or higher than the amount of PTE 75,000,000  (seventy five millions
of Portuguese escudos).

     Ninth:  For the purposes  referred to in paragraphs b), c) and d) of number
seven of this  document,  ANTONIO  MIRANDA  may  retain,  for six  months  after
Completion Date, the amount of USD 3,000,000  (three millions  dollars) from the
USD 6,000,000 (six millions dollars) he received under the terms of paragraph a)
of number one of clause 5 of the Promissory Agreement, which he has to return to
AMTROL in accordance  with numbers four and five of clause 20 of the  Promissory
Agreement,  as guarantee  of the  indemnification  for the damages  which may be
caused to ALFA by AMTROL during the period  counting from today's date until the
date of renounce or  dismissal of the  directors  referred to in paragraph a) of
number six of this document.

     Tenth:  If such damages are subject to  quantification  and are equal to or
higher  than USD  3,000,000  (three  millions  dollars),  and if he  presents  a
justified and written  claim,  one for each damage,  within six months  counting
from the date of renounce or dismissal,  ANTONIO  MIRANDA shall keep this amount
as compensation,  without  prejudice of further indemnity if the claimed damages
within the referred to six months are higher than USD 3,000,000  (three millions
Dollars);  if the damages are less than USD 3,000,000  (three millions  Dollars)
ANTONIO  MIRANDA  shall retain the amount  equivalent  to the caused  damage and
shall reimburse AMTROL with the remaining.

     Eleventh:  The  Parties  expressly  undertake  to submit any  situation  to
arbitration,  under the terms of clause 21 of the Promissory Agreement, to solve
any dispute which may result in the  application  of the numbers 8 and 9 of this
document.


     The Partied accept the contents of this  document,  which forms part of the
Promissory Agreement and are going to sign two counterparts,  each of them is an
original.


                                                           Porto, 30th June 1997

ANTONIO BRANDAO MIRANDA



AMTROL Inc.