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PEI/RP1200 - 12 <br /> 4. 2.4 Preparation. The procedures in this sec- 4. 2. 7 Test Equipment. Test equipment shall <br /> tion are general in nature and reflect the suggested include, <br /> vacuum levels and hold times for testing tank a vacuum-generating device that can be used in <br /> secondary containment areas . Consult tank manu - a Class I, Division 1 area capable of pulling 15 <br /> facturer and authority having jurisdiction (AHJ) inches of mercury (Hg) vacuum; <br /> guidelines before performing these tests as their <br /> requirements may differ. an automatic vacuum shutoff valve or vacuum <br /> regulator (The shutoff valve can be set to close at <br /> Determine if there is liquid present in the intersti- a predetermined safe level , preventing the pos - <br /> tial space. If liquid is found, determine if the fluid . .,1111pi-I . . <br /> is water or product, and remove it to the extent <br /> practicable. <br /> dd <br /> j f �LLtl • II+A? / <br /> N 1? <br /> �� 'p:.kt'•N <br /> The hydrostatic pressure from a high water table -�, ;%a; . <br /> Y A g <br /> .Y" <br /> imposes inward pressure on the outer wall of a pE_. <br /> UST. Applying a vacuum to the interstitial space �n¢ ' '' ! t <br /> 1pb U 1' <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 , y „ , , , „ < <br /> Consequently, to prevent damage to the tank, it is 4; '. <<. 41',.E E” <br /> important to observe the water table and associated ' <br /> recommended vacuum levels when testing . �,"s' ` ht 4E- >,Flo No <br /> Vent the primary tank to atmosphere during the FIGURE 43 . The vacuum gauge and control valve used <br /> tests for tank Interstitial testing. <br /> In some installations, , the tank interstitial space <br /> may be vented to minimize the buildup of conden- F' z3 <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 /> ilk'- n�i . t •.c' ` 5 ,:-,: i ;, . <br /> tion is available from facility records or the auto- <br /> . <br /> uratic tank gauge (ATG) readout. <br /> 4. 2. 5 Steel Tanks. Determine if the interstitialy } 'F``' <br /> 1 <br /> space is a "tight wrap" design or a " 110% contain- : i • r <br /> A g A g _, : ;<s4. <br /> ment" design . Tanks with a 110% containment <br /> design should use the latest version of Steel Tank <br /> Institute's (STI) Recommended Practice 8012, <br /> Recommended Practice for Interstitial Tightness ; <br /> Testing of Existing Underground Double Wall Steel <br /> Tanks for testing. <br /> For tight wrap tanks , use the test method in this <br /> section , <br /> 4 .2 .6 Fiberglass Tanks. Determine if the inter- <br /> %%. 1 . <br /> stitial spaceace is a "tight wra " de <br /> s <br /> ignora « 11. 0 / <br /> r <br /> containment" design . Either type of fiberglass tank ; ` <br /> F n <br /> may use this test, or the latest version of Fiber- 0 <br /> 14 d <br /> , • <br /> glass Tank & Pipe Institute 's, Field Test Protocol r ,. <br /> for Testing the Annular Space of Installed Under- FIGURE 44 . The plumber's plug provides a leak tight <br /> ground Fiberglass Double and Triple- wall Tanks connection to draw a vacuum on the tank Interstitial <br /> with Dry Annular Space, FT&PI 4/01 /07 . space. <br /> Qpei .org <br />