Issue Date: November 22, 1995
Revision Date: October 2, 2003

Praxair Services, Inc.
(originally listed as Tracer Research Corp.)

Tracer Tight


Certification Leak rate of 0.1 gph with PD = 100% and PFA = 0%. 
Leak rate of 0.005 gph with PD = 97% and PFA = 2.9%.
Leak Threshold A tank system should not be declared tight when tracer chemical greater than the background level is detected outside of the tank system.
Applicability Gasoline, diesel, aviation fuel, fuel oil #4, waste oil. 
Tank Capacity Not limited by capacity.
Waiting Time Ranges from 7 to 30 days after tracer is added to tank without support of on-site leak simulation.
The waiting period may be adjusted below this range when supported by on-site leak simulations performed as described below.
Leak Simulations The release of surrogate tracer into the soil or backfill to evaluate the migration of a tracer and the sensitivity of the test under on-site sub-surface conditions. Sub-surface conditions throughout the test area must be at least as favorable as those at the leak simulations location in order to use the results. This requirement may be satisfied by sampling the backfill material, and/or making flow/vacuum measurements from the sampling probes.
Tracer Dosage Dosage of tracer is based on tank size, product volume in tank, and frequency and volume of tank refills according to manufacturer's recommendations.
Permeability Soil permeability must readily allow tracer movement through the tank excavation backfill (greater than 1 Darcy).
Probe Radius of influence of each tracer sampling probe is maximum 10 feet. 
All tank surfaces must be within the zone of influence of a sampling probe. 
Probes must be installed per manufacturer's guidelines.
Horizontal sampling probes may be installed in manufactured backfill during the installation of a new UST system. These probes must be installed per manufacturer’s guidelines.
Groundwater Depth to groundwater in tank excavation backfill must be determined. 
For test method to detect a release of tracer chemical below groundwater, the hydrostatic pressure of product in the tank must exceed the hydrostatic pressure of groundwater during test. 
To accomplish this, product level must be maintained at least 6 inches above groundwater for a minimum 17 hours during the first three days following addition of tracer to the tank. 
At the discretion of the regulatory agency, water ingress measuring devices may be used to supplement test method in high groundwater conditions.
Comments The tester may determine that pre or post testing is needed to establish the background level of tracer in the soil.
The presence of a layer of water saturated soil, that is also frozen, above the location where a leak may exist, may inhibit the effectiveness of the method by impeding the transport of the tracer labeled product into the unsaturated zone.
Groundwater above bottom of tank may limit effectiveness of test method (e.g. when applied to tanks containing water-miscible products or products whose specific gravity is greater than 1).


Praxair Services, Inc.

Evaluator:  Ken Wilcox Associates

3755 N. Business Center Dr.

Tel:  (816) 443-2494

Tucson, AZ  85705

Date of Evaluation:  10/04/90

Tel:  (800) 394-9929

Evaluator: Control Strategies Engineering (out of business)


Tel: Contact Praxair Services, Inc.


Date of Evaluation:  05/92


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