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                                                                  Exhibit 8.2

                   [GRAY CARY WARE & FREIDENRICH Letterhead]


                                        May 29, 1996

Infrasonics, Inc.
3911 Sorrento Valley Boulevard
San Diego, CA 92121

        RE:     JOINT PROXY STATEMENT/PROSPECTUS AND
                REGISTRATION STATEMENT ON FORM S-4

Ladies and Gentlemen:

        We have acted as counsel to Infrasonics, Inc., a California corporation
("Infrasonics"), in connection with the Amended and Restated Agreement and Plan
of Merger, dated as of May 14, 1996 (the "Merger Agreement"), between
Infrasonics and Nellcor Puritan Bennett Incorporated, a Delaware corporation
("NPB"). Capitalized terms not defined herein have the meanings given to them
in the Merger Agreement.

        Pursuant to the Merger Agreement, Infrasonics will merge with and into
NPB (the "Merger"). As a result of the Merger, Infrasonics will no longer exist
and the former stockholders of Infrasonics will receive shares of NPB's common
stock on the terms set forth in the Merger Agreement.

        The Merger Agreement and certain proposed transactions incident thereto
are described in the Registration Statement on Form S-4 filed by NPB with the
Securities and Exchange Commission (the "Registration Statement"). This opinion
is being rendered pursuant to the requirements of Item 21(a) of Form S-4 under
the Securities Act of 1933, as amended.

        In connection with this opinion, we have examined and are familiar with
the Merger Agreement, the Registration Statement, and such other presently
existing 
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GRAY CARY WARE & FREIDENRICH

Infrasonics, Inc.
May 29, 1996
Page 2

documents, records and matters of law as we have deemed necessary and
appropriate in connection with rendering this opinion.

        In rendering this opinion, we assume the following:

        1.      The authenticity of original documents submitted to us, the
conformity to original documents of all documents submitted to us as photostatic
copies and the authenticity of the originals of such copies, the genuineness of
all signatures and the due execution and delivery of all documents.

        2.      The truth and accuracy of the representations, warranties and
statements of fact made or to be made by NPB and Infrasonics in connection with
the Merger, including those representations set forth in the Merger Agreement
and in certificates of representations provided or to be provided to us by NPB
and Infrasonics.

        Based upon and subject to the foregoing, the discussion contained in
the proxy statement/prospectus included as part of the Registration Statement
(the "Prospectus") under the caption "Certain Federal Income Tax Consequences,"
expresses our opinion as to certain of the material Federal income tax
consequences if the Merger is effected according to the terms of the Merger
Agreement. Because this opinion is being delivered prior to the Effective Time
of the Merger, it must be considered prospective and dependent upon future
events. In addition, you should be aware that the discussion under the caption
"Certain Federal Income Tax Consequences" in the Prospectus represents our
conclusions as to the application of existing law to the instant transactions
and may not be applicable to certain classes of Infrasonics stockholders,
including securities dealers, foreign persons and persons who acquired their
Infrasonics Common Stock pursuant to the exercise of employee stock options or
rights or otherwise as compensation. There can be no assurance that changes in
the law will not take place which could affect the Federal income tax 
consequences of the Merger or that contrary positions may not be taken by the
Internal Revenue Service.

        This opinion is furnished to you solely for use in connection with the
Registration Statement. We hereby consent to the filing of this opinion as an
exhibit to the Registration Statement. We also consent to the references to our
firm name wherever appearing in the Registration Statement with respect to the
discussion of the Federal income tax consequences of the Merger, including the
Prospectus constituting a part thereof, and any amendments thereto. In giving
this consent, we

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GRAY CARY WARE & FREIDENRICH



Infrasonics, Inc.
May 29, 1996
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do not thereby admit that we are in the category of persons whose consent is
required under Section 7 of the Securities Act of 1933, as amended.


                                Very truly yours,


                                GRAY CARY WARE & FREIDENRICH