Issue Date: June 4, 2003
Revision Date: April 28, 2005
MassTech International, Ltd.
MassTech Remote Spectral Analysis Method
(Vacuum Test)
Non-Volumetric Tank Tightness Test Method (Ullage)
| Certification | Leak rate of 0.1 gph with PD = 100% and PFA = 0%. |
|---|---|
| Leak Threshold | Tank ullage should not be declared tight when the digital recording of the noise spectrum of tank under vacuum has a detectable difference from the digital recording of the noise spectrum of tank at zero pressure. |
| Applicability | Gasoline, diesel, aviation fuel, fuel oil #4, waste oil. Empty tanks may also be tested. Tanks containing other liquids may be tested after consultation with the manufacturer. Tests only ullage portion of the tank.Product-filled portion of the tank must be tested using an underfill test method. |
| Tank Capacity | Maximum ullage volume is 20,000 gallons. |
| Waiting Time | None between delivery and testing. |
| Test Period | A nominal vacuum of 1.5 psig must be maintained in the ullage. |
| Test Pressure | A nominal vacuum of 1.5 psig must be maintained in the ullage. |
| Temperature | Acoustic signal is independent of product temperature. |
| Groundwater | Depth to groundwater in tank excavation backfill must be determined. If groundwater or other liquid is present outside tank ullage, test must not be used. |
| Comments | Microphone (hydrophone) should be located within 25 feet of any possible leak source. Data are digitally recorded so that it can be reviewed by the test operator or other qualified individuals. Since the method depends on an audible interpretation of the signal, the test must be conducted under reasonably quiet conditions.Vibrations due to heavy traffic, nearby trains, or construction activities could produce sound levels that could compromise the test. Vacuum test method may not be effective in some tank excavation backfill (such as clay) because it may plug holes in tank. If free product is present in tank excavation backfill, a leak in the free product zone may not be detected by a vacuum test method. A well point or observation well in the tank excavation backfill may help determine backfill material, water level in tank excavation backfill, and free product. Operators must be trained and certified by the manufacturer. |
- MassTech International, Ltd.
102 Basile Road
Scott, LA 70583
Tel: (337) 896-8230 - Evaluator: Ken Wilcox Associates, Inc.
Tel: (816) 443-2494
Date of Evaluation: 01/02/01
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