Document:

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                                                                    EXHIBIT 10.2

                             [SYSTEMONE LETTERHEAD]

                                February 27, 2002

To the Investors and Lenders set
forth on the signature page hereto:

                  RE: SERIES B CONVERTIBLE PREFERRED STOCK PURCHASE AGREEMENT
                  DATED AS OF MAY 6, 1999 (THE "SERIES B AGREEMENT") BETWEEN
                  MANSUR INDUSTRIES INC., NOW KNOWN AS SYSTEMONE TECHNOLOGIES
                  INC. (THE "COMPANY"), AND THE INVESTORS NAMED IN SCHEDULE I
                  THERETO (THE "SERIES B INVESTORS");

                           SERIES C CONVERTIBLE PREFERRED STOCK PURCHASE
                  AGREEMENT DATED AS OF AUGUST 24, 1999 (THE "SERIES C
                  AGREEMENT") BETWEEN THE COMPANY AND THE INVESTOR NAMED THEREIN
                  (THE "SERIES C INVESTOR");

                           SERIES D CONVERTIBLE PREFERRED STOCK PURCHASE
                  AGREEMENT DATED AS OF MAY 2, 2000 (THE "SERIES D AGREEMENT")
                  BETWEEN THE COMPANY AND THE INVESTORS NAMED IN SCHEDULE I
                  THERETO (THE "SERIES D INVESTORS"); AND

                           LOAN AGREEMENT DATED AS OF AUGUST 7, 2000, AS AMENDED
                  TO DATE (THE "LOAN AGREEMENT" AND, TOGETHER WITH THE SERIES B
                  AGREEMENT, THE SERIES C AGREEMENT AND THE SERIES D AGREEMENT,
                  THE "AGREEMENTS") BETWEEN THE COMPANY AND THE LENDERS NAMED
                  THEREIN (THE "LENDERS" AND TOGETHER WITH THE SERIES B
                  INVESTORS, THE SERIES C INVESTOR AND THE SERIES D INVESTORS,
                  THE "INVESTORS").

Ladies and Gentlemen:

         Pursuant to the Agreements, the Company has issued to the Investors
shares of preferred stock convertible into common stock of the Company and
warrants to purchase common stock of the Company. For purposes hereof,
capitalized terms utilized and not otherwise defined herein shall have the
meanings ascribed to them in the Agreements, respectively, as applicable in the
context used. Under the Agreements, the Company has agreed to register under
state and federal securities laws the Registrable Securities for resale by the
holders of Registrable Securities (as defined in the Agreements) (such
obligations being referred to herein as the "REGISTRATION OBLIGATIONS").

         In accordance with the Registration Obligations arising under the
Series B Agreement and the Series C Agreement, the Company effected registration
of the applicable Registrable Securities under the Securities Act of 1933, as
amended (the "SECURITIES ACT"), pursuant to an effective registration statement
on Form S-3 (Registration Statement Number 333-86757) and filed a registration
statement on Form S-3 (Registration Statement Number 333-44962) with respect to
the Registrable Securities under the Series D Agreement and the Loan Agreement,
which registration statement is not yet effective. The Company's Registration
Obligations under the Series D Agreement and the Loan Agreement to cause
Registration Statement Number 333-44962 to become effective were waived to not
later than May 30, 2001 pursuant to the Consent Agreement dated as of November
22, 2000 between the Company and the Series D Investors and the Lenders.

         As a result of the delisting of the Company's common stock from the
Nasdaq Stock Market, the Company is no longer eligible to use Form S-3 to effect
registration of the Registrable Securities for resale. As a result, the cost of
effecting and maintaining the effectiveness of registration of the Registrable
Securities has been greatly increased; such additional costs and fees would
adversely and unnecessarily affect the Company's operating results inasmuch as
the market price of the Company's common stock is lower than the conversion or

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exercise prices applicable to the Registrable Securities. Furthermore, the
amount of Registrable Securities that could be sold without registration
pursuant to Rule 144 under the Securities Act (assuming compliance with the
provisions of Rule 144, including the holding period requirements) far exceeds
the number of shares that could be sold economically into the market given the
low trading volume for the Company's common stock.

         Accordingly, in order to avoid such unnecessary cost and expense and in
consideration of the additional rights granted to the holders of Registrable
Securities herein, the Company hereby requests that the Investors agree as
follows:

         (a) The Company shall not be required to fulfill its obligations to
file a Registration Statement with respect to the Registrable Securities under,
respectively, the Series D Agreement or the Loan Agreement unless and until, in
each case, the Company shall have received a written notice from one or more
holders of Registrable Securities thereunder stating that there is on the part
of such person or persons giving such notice a bona fide intent to sell
Registrable Securities having a Current Market Value (as hereinafter defined) of
not less than $1 million and requesting that the Company effect registration of
such Registrable Securities in accordance with the applicable Registration
Obligations (a "DEMAND NOTICE"). If the Company receives a Demand Notice, it
shall promptly notify any other holders of Registrable Securities under the
Series D Agreement and the Loan Agreement not party to such Demand Notice of its
receipt of such Demand Notice and the Company shall include in any such
registration, the Registrable Securities of such other holders of Registrable
Securities thereunder to the extent requested, and such holders shall cooperate
to the extent required by the terms of the Registration Obligations set forth in
such agreements, respectively. The Company shall prepare and file such
Registration Statement (or at its option amend Registration Statement Number
333-44962 if not previously withdrawn) and use its reasonable best efforts to
cause such registration statement to become effective not later than the 120th
day after the Company's receipt of the Demand Notice; PROVIDED, HOWEVER, that if
in the good faith opinion of the board of directors of the Company, such
registration would require the Company to make a disclosure that would be
materially detrimental to the Company's best interests, then the Company shall
be entitled to defer such registration for not more than 120 days. If such
registration statement is not declared effective by the 120th day after the
Company's receipt of the Demand Notice (subject to extension pursuant to the
preceding proviso), then the Company shall be required to pay to the Series D
Investors or the Lenders, as the case may be, Liquidated Damages (as defined in
the Agreement applicable to the affected Registrable Securities) in accordance
with the Series D Agreement or the Loan Agreement, as the case may be, such
Liquidated Damages to commence accruing from and including the 121st day after
the Company's receipt of the Demand Notice (subject to extension as aforesaid).
Upon receipt of a Demand Notice (but subject to the proviso of the second
preceding sentence) the Company and the holders of Registrable Securities
participating in the registration contemplated thereby shall otherwise comply
with the other applicable provisions of the Registration Obligations set forth
in the Series D Agreement and the Loan Agreement.

         (b) For purposes hereof, "CURRENT MARKET VALUE" per Registrable
Security shall be calculated, on any date, on the basis of the average, for 30
consecutive trading days commencing 45 days before such date, of the last sale
price thereof on each such day on the principal stock exchange or the Nasdaq
National Market on which it is then listed or admitted to trading, and if no
sale takes place on any such day on any such exchange or market, the average of
the last reported closing bid and asked prices on such date as officially quoted
on any such exchange or market; and if such Registrable Security is on any day
during such 30 day period not listed or admitted to trading on any stock
exchange or such market, the average of the last reported closing bid and asked
prices on such day in the over-the-counter market, as furnished by Nasdaq or the
National Quotation Bureau, Inc.; and if neither such corporation at the time is
engaged in the business of reporting such prices, as furnished by any similar
firm then engaged in such business, or if there is no such firm, as furnished by
any member of the National Association of Securities Dealers Inc. selected by
the Board of Directors of the Company in good faith and approved by the holder
or holders of Registrable Securities delivering such Demand Notice in question
(such approval not to be unreasonably withheld or delayed).

         (c) If the Company determines to register any equity securities for
sale (other than pursuant to Form S-8 or Form S-4 or any successor forms under
the Securities Act), then if any Registrable Securities remain unsold, the
Company shall give prompt notice of such determination and allow the holders of
Registrable Securities to request the inclusion of their Registrable Securities
in such offering; PROVIDED, HOWEVER, that, if such offering is an underwritten

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offering and the managing underwriters advise the Company in writing that in
their opinion the total number or dollar amount of securities to be included in
such registration exceeds the number or dollar amount of securities which can be
sold in such offering, the Company shall include in such registration: (i)
first, all securities requested to be included in such registration by any
securityholders initiating such registration; (ii) second, all securities the
Company proposes to sell; and (iii) third, the Registrable Securities requested
to be included in such registration which, in the opinion of such underwriters,
can be sold (allocated pro rata among the holders of such Registrable Securities
on the basis of the number of securities requested to be included therein by
each such holder). The Company shall pay all Registration Expenses of any such
offering and each holder of Registrable Securities shall pay its Selling
Expenses. Any holders of Registrable Securities participating in an underwritten
offering shall, as a condition to such participation, execute an underwriting
agreement in the form required by such underwriter containing customary
representations, warranties, covenants, conditions and indemnifications. In all
other respects, the Company's Registration Obligations set forth in the
applicable Agreement shall apply in respect of Registrable Securities included
in a registration pursuant to this paragraph (c). A registration of Registrable
Securities pursuant to this paragraph (c) shall not be counted as a Demand
Registration.

         (d) Notwithstanding its Registration Obligations set forth in the
Series B Agreement or the Series C Agreement, if the Company is not eligible to
use Form S-3 for the purpose of amending registration statement Number
333-86757, then the Company shall not be required to amend such registration
statement unless and until the Company shall have received a written notice from
one more holders of Registrable Securities under the Series B Agreement or the
Series C Agreement stating that there is on the part of such person or persons
giving such notice a bona fide intent to sell shares of such Registrable
Securities having a Current Market Value of not less than $1 million and
requesting that the Company effect an amendment of such registration statement
so that sales of such Registrable Securities pursuant thereto may resume (an
"AMENDMENT NOTICE"). The Company shall prepare and file such amendment and use
its reasonable best efforts to cause such amendment to become effective not
later than the 120th day after the Company's receipt of the Amendment Notice;
PROVIDED, HOWEVER, that if in the good faith opinion of the board of directors
of the Company, such amendment would require the Company to make a disclosure
that would be materially detrimental to the Company's best interests, then the
Company shall be entitled to defer the filing of such amendment for not more
than 120 days. If such amendment is not declared effective by the 120th day
after the Company's receipt of the Amendment Notice (subject to extension
pursuant to the preceding proviso), then the Company shall be required to pay
the Series B Investors or the Series C Investor, as the case may be, Liquidated
Damages in accordance with the Series B Agreement or the Series C Agreement, as
the case may be, such Liquidated Damages to commence accruing from and including
the 121st day after the Company's receipt of the Amendment Notice (subject to
extension as aforesaid).

         (e) Except to the extent payment is required hereby, the Investors
waive the payment of any Liquidated Damages which may have accrued to the date
hereof or hereafter accrue (but for the fact that this letter agreement shall
have been entered into) pursuant to the Agreements.

         (f) The Company may at its option withdraw Registration Statement
Number 333-44962.

         (g) Without limiting the generality of the foregoing: (i) all
indemnification and contribution provisions of the Agreements, and all
provisions regarding registration and compliance under the Exchange Act and
listing, shall remain in full force and effect and, without limitation, apply,
respectively, to performance hereunder; and (ii) the effectiveness of each
Registration Statement hereunder shall be maintained by the Company through the
applicable Effectiveness Period.

         (h) The provisions hereof shall inure to the benefit of the parties
hereto and their respective permitted successors and assigns.

               [remainder of this page intentionally left blank]

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         If the foregoing is acceptable, please execute a copy of this letter
agreement in the space provided and return such executed copy to the
undersigned.

                                              Very truly yours,

                                              SYSTEMONE TECHNOLOGIES INC.

                                              By: /s/ PAUL I. MANSUR
                                                  -----------------------------
                                                  Paul I. Mansur
                                                  Chief Executive Officer

Agreed to an accepted as of the date first above written:

Investors and Lenders:

ENVIRONMENTAL OPPORTUNITIES FUND II, L.P.     HANSEATIC AMERICAS LDC
ENVIRONMENTAL OPPORTUNITIES FUND II
(INSTITUTIONAL), L.P.                         By:  Hanseatic Corporation

By:  Fund II Mgt. Co., LLC                             By: /s/ PAUL A. BIDDELMAN
     General Partner                                       ---------------------
                                                           Paul A. Biddelman
                                                           President

         By: /s/ KENNETH C. LEUNG
            ----------------------------
         Kenneth C. Leung
         Chief Investment Officer

ENVIRONMENTAL OPPORTUNITIES FUND, L.P.
ENVIRONMENTAL OPPORTUNITIES FUND  (CAYMAN), L.P.

By:  Environmental Opportunities Management Co., LLC
     General Partner

         By: /s/ BRUCE McMAKEN
            ----------------------------
            Bruce McMaken
            Manager

                                       4<PAGE>
                                                                    EXHIBIT 10.3

                                                               February 27, 2002

Hanseatic Americas LDC
450 Park Avenue
New York, New York 10022

Environmental Opportunities Fund II LP
Environmental Opportunities Fund II
 (Institutional) LP
c/o Sanders Morris Harris
3100 Chase Tower
600 Travis Street
Houston, Texas 77002

Dear Sirs:

         Reference is hereby made to:

         (i)      the Loan Agreement dated as of August 7, 2000, as amended by
                  Amendment No. 1 dated as of November 10, 2000, Amendment No. 2
                  dated November 30, 2000 and Amendment No. 3 dated the date
                  hereof (the foregoing, as from time to time further amended,
                  collectively referred to as the "Amended Loan Agreement")
                  entered into among us; and

         (ii)     the Supplemental Letter dated August 7, 2000 (the
                  "Supplemental Letter") executed by you and the undersigned,
                  together with the concurring shareholders executing this
                  letter (a copy of which is annexed hereto).

Capitalized terms utilized herein and not otherwise defined herein shall have
the meanings assigned to them in the Amended Loan Agreement.

         This letter shall confirm that the Supplemental Letter remains in full
force and effect, and that all references therein to the Loan Agreement shall be
deemed references to the Amended Loan Agreement.

                                        Very truly yours,

                                        SYSTEMONE TECHNOLOGIES, INC.

                                        By /s/ PAUL I. MANSUR
                                          -------------------------------------
                                        Paul I. Mansur
                                        Chief Executive Officer

<PAGE>

AGREED:

ENVIRONMENTAL OPPORTUNITIES FUND II, L.P.     HANSEATIC AMERICAS LDC

ENVIRONMENTAL OPPORTUNITIES FUND II
(INSTITUTIONAL), L.P.                         By:  Hanseatic Corporation

By:  Fund II Mgt. Co., LLC                           By: /s/ PAUL A. BIDDELMAN
                                                        ------------------------
     General Partner                                 Paul A. Biddelman
                                                     President

         By: /s/ KENNETH C. LEUNG
             ----------------------------
         Kenneth C. Leung
         Chief Investment Officer

   The undersigned concurring shareholders agree to the foregoing:

/s/ PIERRE G. MANSUR
------------------------------------
Pierre G. Mansur

/s/ PAUL I. MANSUR
------------------------------------
Paul I. Mansur

ENVIRONMENTAL OPPORTUNITIES FUND, L.P.
ENVIRONMENTAL OPPORTUNITIES FUND  (CAYMAN), L.P.

By:  Environmental Opportunities Management Co., LLC
     General Partner

         By:/s/ BRUCE MCMAKEN
            -------------------------
         Bruce McMaken
         Manager

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