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Recommended Practices for the Testing and Verification of Spill,Overfill,Leak Detection and Secondary Containment Equipment at UST Facilities <br /> CAUTION: Use only an air-operated vacu- For tight-wrap tanks, use the test method in this <br /> section. <br /> um source or c vacuum pump powered by <br /> an explosion-proof motor. Vacuum pumps 4.2.6 Fiberglass Tanks. Determine if the inter- <br /> with electric motors that are not explo- stitial space is a "tight-wrap" design or a "110% <br /> cion-proof may ignite flammable vapors. containment"design.Either type of fiberglass tank <br /> If a portable air compressor is used, it may use this test or the latest version of Fiberglass <br /> should be located at least 20 feet away Tank&Pipe Institute's (FIPI)RP 2007,Field Test <br /> from the venturi-eductor or outside any Protocol for Testing the Annular Space of Installed <br /> Class 1, Division 1 area. <br /> 4.2.4 Preparation. The procedures in this sec- <br /> tion are general in nature and reflect the suggested <br /> vacuum levels and hold times for testing tank f rt <br /> secondary containment areas. Consult tank mann- <br /> facturer and authority having jurisdiction (AHJ) <br /> guidelines before performing these tests, as their ' <br /> requirements may differ. =# <br /> Determine if there is liquid present in the intersti- <br /> tial space.If liquid is found, determine if the fluid <br /> is water or product, and remove it to the extent s } <br /> practicable. FIGURE 4.3. The vacuum gauge and control valve used <br /> The hydrostatic pressure from a high water table for tank interstitial testing. <br /> imposes inward pressure on the outer wall of a <br /> UST. Applying a vacuum to the interstitial space <br /> of the tank creates additional pressure on the outer <br /> wall. These combined forces can damage the <br /> secondary tank wall when there is a large defined , <br /> space between the primary and secondary tanks. <br /> Consequently, to prevent damage to the tank, it is � s <br /> important to observe the water table and associated ' 4 <br /> recommended vacuum levels when testing. <br /> Vent the primary tank to atmosphere during the ; Y <br /> test. ! IFA <br /> In some installations, the tank interstitial space <br /> may be vented to minimize the buildup of conden- <br /> sation.In these cases, seal off any vent lines to the <br /> tank interstitial space prior to testing. <br /> Determine the volume of the tank. This informa- <br /> tion is available from facility records or the auto- <br /> matic tank gauge(ATG)readout. <br /> 4.2.5 Steel Tanks. Determine if the interstitial <br /> r � <br /> space is a"tight-wrap" design or a"110%contain- <br /> ment" design. Tanks with a 110% containment �- <br /> design should use the latest version of Steel Tank _ <br /> Institute's (STI) R012,Recomanended Practice for <br /> Interstitial Tightness Testing of Existing Under- FIGURE 4-4. The plumber's plug provides a leak-tight <br /> ground Double Wall Steel Tanks for testing. connection to draw a vacuum on the tank interstitial <br /> space. <br /> pei.org 0 <br />