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FROM COMPRESSOR <br />PRESSURE RELIEF DEVICE <br />AIR SUPPLY VALVE <br />AIR SUPPLY GAUGE RESERVOIR FITTING <br />SERVICE FITTING <br />FIGURE 2-4 <br />SECONDARY (EXTERNAL) -TANK TEST <br />CAUTION: Do not pressurize the secondary tank (interstitial space) <br />or the primary tank may rupture and cause tank failure. <br />Check the exterior of the tank for monitoring liquid — if liquid is <br />found, wipe the tank dry and verify that the liquid does not <br />reappear. Lift the tank to check the bottom. Do not roll the tank. <br />DANGER: Do not stand under the tank while it is being lifted. <br />When the test is complete, remove the test manifold. Usually <br />check the interior of the tank for liquid. Replace the protective <br />covers in the service fitting and the reservoir fitting. <br />3ACKFILL AND BFDr <br />Xerxes tanks must be installed using either pea gravel or crushed <br />stone which meets the following specifications. <br />GENERAL: The material is washed and free flowing and conforms <br />to the specification of ASTM C-33 para. 9.1, sizes 6 through 8. No <br />more than 5% (by weight) of the material may pass through a #8 <br />sieve. It is recommended that the supplier certify that the material <br />conforms to ASTM C-33 and any other applicable specifications. <br />(For additional information, refer to the Xerxes pamphlet fiberglass <br />Tank Backfill Guidelines.) <br />PEA GRAVEL CRUSHED STONE <br />PEA GRAVEL: Mix of rounded particles — sizes between 1/8" <br />and 3/4". <br />CRUSHED STONE: Mix of angular particles — sizes between 1/8" <br />and 1/2". <br />NOTE: If material which meets these specifications is not available, contact the <br />it, Xerxes Technical Service Department for information on approved alternate <br />materials and installation instructions. Using other than approved bedding and back- <br />fill materials without Xerxes' prior written approval will void the tank warranty and <br />may result in tank failure. <br />4. EXCAVATION PARAMETERS <br />The installing contractor must take all precautions necessary to <br />protect employees working in or near a tank excavation. These <br />precautions should include, but are not limited to: <br />• Location and protection of any utility installations near the <br />excavation before opening the excavation; <br />• Means of securing the walls of the excavation; <br />• Means of preventing exposure of employees to hazardous <br />fumes from the excavation; <br />• Protection of employees from hazards associated with water <br />accumulation in the excavation; <br />• Barricades, etc. to prevent unauthorized vehicle or pedestrian <br />traffic; <br />• Inspection of the excavation and surrounding area at least daily. <br />For additional information on excavation, trenching and shoring <br />safety practices, consult OSHA's Construction Industry Standards <br />Part 1926, Subpart P. <br />The minimum depth of the excavation is normally determined by <br />the presence or absence of groundwater and the presence or <br />absence of traffic at the site. These dimensions are critical to the <br />successful installation of a tank and are often regulated by code. <br />Refer to: <br />• federal, state and <br />local codes <br />• NFPA 30 & API 1615 <br />• the figures below. <br />NOTE: Numbers in brackets [ ] <br />refer to 12' tanks. <br />Tanks subjected to traffic loads must have a cover depth of at least <br />18 [36] inches of backfill plus 9 inches of asphalt. An acceptable <br />alternative is a minimum of 18 [36] inches of backfill plus 6 inches <br />of reinforced concrete. <br />NOTE: Numbers in brackets [ ] <br />refer to 12' tanks. <br />Tanks subjected to traffic loads and high water must have a <br />minimum of 30 [36] inches of backfill and either 9 inches of <br />asphalt or 6 inches of reinforced concrete. <br />