Issue Date: April 28, 2005
MassTech International, Ltd.
MassTech 002 Ullage Test System (Pressure or 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 a predetermined threshold is exceeded. This threshold may be modified by the results of the static test. |
| 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 30,000 gallons. |
| Waiting Time | 2.38 hours with tank filled to 5% 1.5 hours with tank filled to 50% 0.27 hours with tank filled to 95% The wait time may be shortened by the technician when steady state conditions are reached earlier. |
| Test Period | Total collection time is 2.63 hours with tank filled to 5% Total collection time is 1.75 hours with tank filled to 50% Total collection time is 0.52 hours with tank filled to 95% The 25-minute static test in which the tank is sealed but not pressurized may be shortened by the technician when steady state conditions are reached earlier. Test data is acquired by computer and forwarded electronically to an analysis center where proprietary software is used to assist in the determination of the tank condition. |
| Test Pressure | A nominal pressure or vacuum of 1.5 psig must be maintained in the ullage. |
| Temperature | Method is sensitive to temperature, atmospheric pressure and other environmental fluctuations. These are empirically modeled during the static test. |
| Groundwater | Depth to groundwater in tank excavation backfill must be determined.If groundwater is above tank bottom, a water sensor must be located at the bottom of the tank or the test must be conducted in conjunction with the standard MassTech wet test. |
| Comments | 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: 02/21/05
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