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

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

Tracer Tight Line Test


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 pipeline system should not be declared tight when tracer chemical greater than the background level is detected outside of the pipeline.
Applicability Gasoline, diesel, aviation fuel, fuel oil #4, waste oil. 
Pipeline Capacity Not limited by capacity.
Waiting Time Ranges from 7 to 30 days after tracer is added to tank without support of on-site simulation.
The waiting period may be adjusted below this range when supported by on-site leak simulations performed as described below.
For very large pipeline systems, several days or weeks may be required to circulate tracer-labeled product through all parts of the pipeline.
Waiting time begins after tracer has reached all portions of the pipeline being tested.
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. 
Tracer-labeled product must be circulated through the pipeline before test period begins. 
Pressurized pipeline must be brought up to operating pressure or operated on a daily basis.
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. 
Pipeline must be accurately located to ensure that all pipeline surfaces are 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.
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 surrounding pipeline may limit effectiveness of test method (e.g. when applied to pipelines 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)
E-mail: Tel: Contact Praxair Services, Inc.


Date of Evaluation:  05/92


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