SUPPLEMENTAL CONFIDENTIALITY
                      AND PROPRIETARY INFORMATION AGREEMENT
                      WITH PROVISION FOR SEVERANCE BENEFIT

     This Supplemental  Confidentiality and Proprietary Information Agreement is
entered  into  between   HydroChem   Industrial   Services,   Inc.,  a  Delaware
corporation, and its parent,  subsidiaries,  and related companies ("HydroChem")
and Dwane Ruiz ("you") as of the 1st day of April, 2000.

     In  consideration  of (i) your  employment by HydroChem in connection  with
Project Whirl or activities  related  thereto or in support  thereof,  (ii) your
future access to certain  proprietary,  confidential or trade secret information
of HydroChem  through  Project Whirl,  (iii)  HydroChem's  payment of salary and
other compensation to you, and (iv) HydroChem's obligations in this Agreement to
provide  you with a  severance  benefit  if your  employment  is  terminated  by
HydroChem without cause, HydroChem and you agree to each of the following:

1.      Confidentiality.  You agree to maintain in strict confidence,  and agree
not to use or disclose  except as authorized by HydroChem,  any information of a
competitively  sensitive or proprietary  nature which you receive from HydroChem
or its  clients or  contractors  in  connection  with your  services  hereunder.
HydroChem agrees to take reasonable steps to identify, and cause its clients and
contractors to identify,  for your benefit such information,  including by using
confidentiality   notices  in  written   material   where   appropriate.   These
restrictions  shall  not be  construed  to  apply to (1)  information  generally
available to the public, (2) information released by HydroChem or its clients or
contractors (as the case may be) generally without restriction,  (3) information
independently  developed or acquired by you without reliance in any way on other
protected  information  of  HydroChem  or its  clients  or  contractors,  or (4)
information approved by HydroChem or its clients or contractors (as the case may
be) for  your  use  and  disclosure  without  restriction.  Notwithstanding  the
foregoing  restrictions,  you may use and disclose any information to the extent
required  by an order of any  court or other  governmental  authority,  but only
after  HydroChem or its clients or contractors (as the case may be) have been so
notified  and  have had the  opportunity,  if  possible,  to  obtain  reasonable
protection for such information in connection with such disclosure.

2.       Return of  Materials.  You must  return to  HydroChem  and leave at its
disposal  all  materials   involving  any  trade  secrets  or   proprietary   or
confidential information of HydroChem. Upon the request of HydroChem and, in any
event,  upon termination of your  employment,  you will leave with HydroChem all
memoranda, notes, records, drawings, manuals, disks or other documents and media
pertaining to HydroChem's business (including all copies thereof).  This section
is intended to apply to all materials made or compiled by you, as well as to all
materials furnished to you by anyone else in connection with your employment.

<PAGE>

3.       Ownership of Employee Developments.

         3.1  Existing Proprietary Rights.  The  patents,  patent  applications,
copyrights,  trade secrets, and trademarks listed on the attached Schedule A are
the only intangible interests and properties that you own, or have any claim in,
at the time of execution of this Agreement.

         3.2  Ownership of Work Product.  All copyrights, patents, trade secrets
or other intellectual  property  rights  associated  with  any  ideas, concepts,
techniques, inventions, processes or works of authorship developed or created by
you  during  the  course  of  performing  work  for  HydroChem  or  its  clients
(collectively,  the "Work  Product")  shall belong  exclusively to HydroChem and
shall,  to the extent  possible,  be  considered a work for hire made by you for
HydroChem  within  the  meaning of Title 17 of the United  States  Code.  To the
extent the Work  Product may not be  considered  a work for hire made by you for
HydroChem, you agree to assign, and automatically assign at the time of creation
of the Work  Product,  without any  requirement  of further  consideration,  any
right,  title or interest  you may have in such Work  Product.  Upon  request of
HydroChem, you shall take such further actions, including execution and delivery
of  instruments  of  conveyance,  as may be  appropriate to give full and proper
effect to such assignment.

4.       Restrictions on Competition.

         4.1  Factual Background.   HydroChem  expects  to  invest  considerable
time,  effort, and capital in enhancing the value and desirability of the skills
of its technical and other  personnel  employed by HydroChem in connection  with
Project Whirl or activities  related  thereto or in support  thereof.  Both this
investment and your individual  compensation reflect HydroChem's  expectation of
receiving a  considerable  return from the  exclusive  use of your  services and
know-how in the future,  free from any danger that  HydroChem's  competitors may
attempt to induce you to leave  HydroChem  and  wrongfully  gain the  benefit of
HydroChem's  investment.  The partial  restraint  set forth in this section does
not,  and  cannot,  provide  complete  protection  for  HydroChem's  investment,
development  efforts,  product  strategy,  and  proprietary   information,   but
HydroChem  believes  that in  combination  with  the  other  provisions  of this
Agreement, it is the most fair and reasonable measure permitted under applicable
law to protect HydroChem's  interests,  giving due regard to both your interests
and the  interests of HydroChem.

         4.2  Avoidance of Conflict of Interest.  While employed  by  HydroChem,
you will not engage in any other  business  activity  that  conflicts  with your
duties to HydroChem.  Under no circumstances will you work for any competitor or
have any financial interest in any competitor of HydroChem;  provided,  however,
that this  Agreement does not prohibit  investment of a reasonable  part of your
assets in the stock or  securities of any  competitor  whose stock or securities
are traded on a national  exchange.

         4.3  Covenant Not to Compete.  You recognize that you may become
familiar
with trade  secrets or  confidential  or  proprietary  information  of HydroChem
pertaining  to  HydroChem's   chemical   cleaning,   hydroblasting,   industrial
vacuuming,  tank cleaning,  mechanical or waste minimization businesses and that
you could  cause  grave harm to  HydroChem  if you worked  for a  competitor  of
HydroChem  anywhere  in the United  States of  America  in any of those  fields.

<PAGE>

Therefore,  AFTER THE TERMINATION OF YOUR EMPLOYMENT,  YOU WILL NOT COMPETE WITH
HYDROCHEM  FOR TWO  YEARS  BY  ENGAGING  IN  CHEMICAL  CLEANING,  HYDROBLASTING,
INDUSTRIAL VACUUMING, TANK CLEANING, MECHANICAL OR WASTE MINIMIZATION BUSINESSES
WITHIN THE UNITED STATES OF AMERICA.  YOU WILL REFRAIN FROM ACTUALLY  PERFORMING
OR DIRECTLY  MANAGING OR  SUPERVISING  SUCH  ACTIVITIES,  WHETHER AS  PRINCIPAL,
AGENT, EMPLOYEE, CONSULTANT, CONTRACTOR OR CO-VENTURER.

This  partial  restraint  shall apply only to the extent  that,  within the year
preceding  the  termination  of your  employment,  you actually  worked in or in
support of any of the areas specified above on behalf of HydroChem.

         4.4  Noninterference with Personnel Relations.  During  your employment
with HydroChem and for a period of two years afterwards,  you will not knowingly
solicit,  entice,  or persuade  any other  employees  of  HydroChem to leave the
services of HydroChem for any reason.

5.       Specific Performance and Consent to Injunctive Relief. Irreparable harm
should be presumed if you breach any  covenant in this  Agreement.  The faithful
observance of all covenants in this Agreement is an essential  condition to your
employment,  and HydroChem is depending upon absolute compliance.  Damages would
probably be very  difficult  to  ascertain  if you breached any covenant in this
Agreement.  This  Agreement  is intended to protect  the  proprietary  rights of
HydroChem  in  many  important  ways.  Even  the  threat  of any  misuse  of the
technology of HydroChem  would be extremely  harmful,  since that  technology is
essential to the business of HydroChem.  In light of these facts, you agree that
any court of competent jurisdiction should immediately enjoin any breach of this
Agreement upon the request of HydroChem,  and you specifically release HydroChem
from the  requirement  of  posting  any bond in  connection  with  temporary  or
interlocutory injunctive relief, to the extent permitted by law.

6.       Severance Benefit. If at any time, HydroChem terminates your employment
without  cause,  then  subject  to  your  compliance  with  this  Agreement  and
HydroChem's  standard form  Proprietary  Information  Agreement which you signed
previously  or  simultaneously  herewith,  HydroChem  will pay to you  severance
compensation  equal to six months of your then  current base  compensation.  Any
severance  compensation  would be payable in bi weekly  installments  as if your
employment  had  continued  for the six month period  after  actual  termination
thereof.  For the purpose of this section 6, "cause"  shall mean (a) the failure
by you to perform your duties in a manner satisfactory to HydroChem,  (b) fraud,
misappropriation,  embezzlement,  or conviction of any felony, or (c) any act or
action involving moral turpitude or reflecting negatively on HydroChem.

7.       Miscellaneous.

         7.1  Related  Parties.  This Agreement shall inure  to  the benefit of,
and be binding upon,  HydroChem and its  subsidiaries  and affiliates,  together
with  their  successors  and  assigns,  and you,  together  with your  executor,
administrator, personal representative, heirs, and legatees.

<PAGE>

         7.2  Severability.  The covenants in  this Agreement shall be construed
as covenants  independent  of one another and as  obligations  distinct from any
other contract  between you and  HydroChem.  Any claim that you may have against
HydroChem  shall not  constitute a defense to  enforcement  by HydroChem of this
Agreement.

         7.3  Survival of Obligations.  The  covenants in  this  Agreement shall
survive termination of your employment, regardless of who causes the termination
and under what circumstances.

         7.4  Choice of Law.  This Agreement shall  be  governed by and enforced
under  the laws of the  State of Texas  as they  apply to a  contract  executed,
delivered  and  performed  entirely  in such  state.  Further,  you  consent  to
jurisdiction  and venue in Harris County,  Texas in connection  with any dispute
arising from this Agreement.

         IN WITNESS WHEREOF, you have accepted and executed this Agreement under
seal as of the date first hereinabove set forth.

                                                     EMPLOYEE:


                                                     /s/ Dwane Ruiz
                                                     --------------
                                                         Dwane Ruiz


Accepted:

HydroChem Industrial Services, Inc.

By /s/ B. Tom Carter
   --------------------
       B. Tom Carter, Jr., Chairman
       And Chief Executive Officer

                                   SCHEDULE A


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/s/DR
---------------
Employee's Initials