EXHIBIT 10.20

                      NON-RECOURSE SECURED PROMISSORY NOTE


          FOR VALUE RECEIVED, Stanley S. Binder (the "Maker") hereby promises to
pay to the order of Barringer  Technologies Inc. or its successors,  assigns and
legal representatives (the "Holder"), at its offices at 219 South Street, Murray
Hill,  New Jersey,  or at such other  location as the Holder may designate  from
time to time,  the sum of Five Hundred  Thousand  Dollars  ($500,000)  in lawful
money of the  United  States of America  (except as set forth  below) on July 6,
2003 (the "Maturity Date"), together with interest thereon, compounded annually,
at a rate of 5.68% per annum. Interest shall be paid annually on the anniversary
of the date hereof.  Principal shall be paid on the Maturity Date, together with
all interest  outstanding as of the Maturity Date.  Interest shall be calculated
on the basis of a 360-day year for the actual number of days elapsed.

          If the date any amount is due  hereunder is not a Business  Day,  then
such amount  shall be due and payable on the Business  Day next  succeeding  the
original payment date, together with interest thereon to the date of payment. As
used herein,  "Business  Day" means any day,  other than a Saturday or Sunday or
other day on which commercial  banks in New York are authorized or required,  by
law or executive order, to be closed.

          If the Maker fails to pay any amount  hereunder  when due,  whether on
the Maturity Date, upon  acceleration or otherwise,  and such failure  continues
for a period of five (5) days or more,  interest shall thereafter  accrue on any
overdue  amounts at a rate of 8.68% per annum until paid in full. In such event,
the Maker  also  shall pay to the  Holder  the  reasonable  attorneys'  fees and
disbursements and all other  out-of-pocket costs incurred by the Holder in order
to collect  amounts  due and owing under this Note or  otherwise  to enforce the
Holder's rights and remedies hereunder.

          The Maker  may  prepay  this  Note at any  time,  in whole or in part,
without premium or penalty.  Any partial  prepayments  shall be applied first to
accrued  interest  and second to the payment of  principal.  The Maker shall not
have  the  right to set off or  otherwise  deduct  from  amounts  payable  by it
hereunder, any amounts, whether liquidated or unliquidated, which the Holder may
owe to the Maker,  which right is hereby  expressly waived to the maximum extent
permitted by  applicable  law. In the event that the Maker  sells,  transfers or
otherwise  disposes  of some or all of the  Shares  (as  defined  in the  Pledge
Agreement  referred to below),  whether on or prior to the  Maturity  Date,  the
Maker shall promptly repay this Note in an amount equal to the net proceeds,  if
any, received by the Maker from such disposition.

          Notwithstanding  anything  set forth  herein to the  contrary,  in the
event that (i) the Holder terminates the Maker's employment with the Holder as a
result of a  Termination  for Cause (as  defined  in the  Amended  and  Restated
Employment   Agreement,   dated  as  of  December  31,  1997  (the   "Employment
Agreement"),  between the Holder and the Maker) or (ii) the Maker terminates his
employment  with the  Holder  other than as a result of a  termination  for Good
Reason (as defined in the Employment Agreement),  this Note shall mature and all
amounts due hereunder  shall become due and payable,  without demand and without
notice to the Maker, 

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within 90 days of the date of  termination.  Notwithstanding  anything herein to
the  contrary,  this Note  shall not  mature  upon the death of the Maker or the
Maker becoming Permanently Disabled (as defined in the Employment Agreement).

          This Note is the Note referred to in the Pledge  Agreement,  dated the
date  hereof,  between  the  Maker  and the  initial  holder of this Note and is
secured by the Shares and the other  Collateral  described  therein.  The Pledge
Agreement  grants the Holder certain rights with respect to the Collateral  upon
certain defaults specified therein.

          The Holder's  sole  recourse for the payment of amounts due under this
Note shall be limited to the Collateral securing this Note. THE HOLDER SHALL NOT
HAVE THE RIGHT TO ENFORCE  THIS NOTE  AGAINST  THE MAKER OR ANY OTHER  ASSETS OR
PROPERTY OF THE MAKER. At the option of the Maker,  the principal amount of this
Note may be paid by the Collateral to the Holder, properly endorsed or otherwise
in proper form for transfer.

          No delay on the part of the  Holder in  exercising  any power or right
hereunder  shall  operate as a waiver of any such power or right;  nor shall any
single or partial  exercise of any power or right  preclude any other or further
exercise  of such power or right,  or the  exercise of any other power or right,
and no waiver whatsoever shall be valid unless in writing, signed by the Holder,
and then only to the  extent  expressly  set  forth  therein.  The Maker  waives
presentment,  demand for  payment,  diligence,  notice of dishonor and all other
notices or demands in  connection  with the delivery,  acceptance,  performance,
default or indorsement of this Note.

          This Note shall be binding upon the Maker and its successors,  assigns
and legal  representatives.  This Note shall be governed  by, and  construed  in
accordance with, the laws of the State of New Jersey,  without  reference to the
choice of law provisions thereof. The Maker irrevocably submits to the exclusive
jurisdiction  of the courts of the State of New  Jersey  and the  United  States
District  Court for the  District  of New  Jersey  for the  purpose of any suit,
action,  proceeding or judgment  relating to or arising out of this Note and the
transactions   contemplated  hereby.  The  Maker  irrevocably  consents  to  the
jurisdiction of any such court in any such suit, action or proceeding and to the
laying of venue in such court. The Maker irrevocably waives any objection to the
laying of venue of any such suit,  action or  proceeding  brought in such courts
and  irrevocably  waives  any claim  that any such  suit,  action or  proceeding
brought in any such court has been brought in an inconvenient forum.

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          IN WITNESS WHEREOF, the Maker has caused this Note to be duly executed
by the undersigned, thereunto duly authorized, as of the date set forth below.


Witness:

/s/Helen Beyerl                            /s/Stanley S. Binder
Name:                                        Stanley S. Binder


Dated:  July 1, 1998