Table 11203 Nonvolumetric Leak Testing Methods

Method

Principle

Claimed Accuracy, gal/h

Total Downtime for Testing

Requires Empty or Full Tank for Test

Acoustical Monitoring System (AMS)

Leybold-Heraeus helium detector, Ultratest M2

Smith & Denison helium test

TRC rapid leak detector for underground tanks and pipes

Ultrasonic leak detector (Ultrasound)

VacuTect (Tanknology)

Varian leak detector (SPY2000 or 938-41)

Sound detection of vibration and elastic waves generated by a leak in a nitrogen-pressurized system; triangulation techniques to detect leak location Rapid diffusivity of helium; mixing of a tracer gas with products at the bottom of the tank; helium detected by a sniffer mass spectrometer Rapid diffusivity of helium; differential pressure measurement; helium detection outside a tank

Rapid diffusion of tracer gas; mixing of a tracer gas with product; tracer gas detected by a sniffer mass spectrometer with a vacuum pump Vacuuming the system (5 lb/in2); scanning entire tank wall by ultrasound device; noting the sound of the leak by headphones and registering it on a meter Applying vacuum at higher than product static head; detecting bubbling noise by hydrophone; estimating approximate leak rate by experience Similar to Smith & Denison

Does not provide leak rate; detects leaks as low as 0.01 gal/h

Does not provide leak rate; helium could leak through 0.005-in leak size

Provides the maximum possible leak detection based on the size of the leak (does not provide leak rates); helium could leak through 0.05-in leak size Does not provide leak rate; tracer gas could leak through 0.005-in leak size

Does not provide leak rate; a leak as small as 0.001 gal/h of air could be detected; a leak through 0.005-in could be detected

Provides approximate leak rate

Similar to Smith & Denison

None

Few—24 h (excludes sealing time)

None

Few hours (includes tank preparation and 20-min test)

Empty

Empty

Few—24 h (excludes sealing time)

Empty

Source: Reprinted from U.S. EPA, 1986.

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