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Automatic Vacuum Control <br />Shutoff Valve Valve <br />0 - 30" Hg <br />Vacuum Gauge <br />Vacuum <br />Source <br />Plumber's <br />Plug <br />Recommended Practices for the Testing and Verification of Spill, Overfill, Leak Detection and Secondary Containment Equipment at UST Facilities <br />interstitial space is raised and is monitored for a speci- <br />fied period of time to determine if the containment has <br />integrity. <br />A tank secondary containment integrity test does not <br />necessarily determine whether the primary tank is tight <br />because portions of the primary tank, such as tank fittings <br />and manway openings, may not be included in the con- <br />tainment integrity test. <br />FIGURE 4-1. A cutaway view of a double-walled tank. <br />4.2 Tank Secondary Containment lntegrtty Testing <br />- Dry Test Method <br />4.2.1 Purpose. This method is used to test the <br />integrity of the dry secondary containment of a <br />UST. <br />4.2.2 Description of Test. A partial vacuum is <br />drawn on the interstitial space and it is monitored <br />for a specified period of time. If the vacuum level is <br />maintained, the containment system has passed the <br />test. The vacuum test time depends on the volume <br />of the annular space and site conditions. <br />4.2.3 Test Conditions. The primary tank may <br />contain any level of product. No bulk deliveries <br />shall occur during the test. <br />CAUTION: Use only an air-operated vacu- <br />um source or a vacuum pump powered by <br />an explosion-proof motor. Vacuum pumps <br />with electric motors that are not explo- <br />sion-proof may ignite flammable vapors. <br />If a portable air compressor is used, it <br />should be located at least 20 feet away <br />from the venturl-eductor or outside any <br />Class I, Division 1 area. <br />Tank <br />FIGURE 4-2. Schematic of the dry test method apparatus. <br />pelorg