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Hazardous Materials Program Guidance: UST Overfill Prevention - Page 7 of 7 k "i 11 ? !i
<br />Xerxes Double -Wall Stand -Alone USTs Manufactured Before 9/1/260h VIHU(° ���� 6 ''� I� 0
<br />tea- R
<br />Size
<br />(Gallons)
<br />Diameter
<br />(Feet)
<br />Actual
<br />Capacity
<br />(Gallons)
<br />Actual
<br />Diameter
<br />(Inches)
<br />90% Volume
<br />(Gallons)
<br />t
<br />90% Height
<br />(Inches)
<br />95% Volume
<br />(Gallons)
<br />95% Height
<br />(Inches)
<br />61000
<br />6
<br />51829
<br />70.25
<br />51246
<br />58.8
<br />5,538
<br />63.1
<br />6,000
<br />8
<br />51998
<br />89.75
<br />51398
<br />74.6
<br />51698
<br />80.1
<br />61000
<br />10
<br />61430
<br />118.25
<br />51787
<br />97.0
<br />61109
<br />104.3
<br />8,000
<br />8
<br />7,841
<br />89.75
<br />71057
<br />74.8
<br />71449
<br />80.3
<br />8,000
<br />10
<br />8,005
<br />118.00
<br />71205
<br />97.5
<br />7,605
<br />104.8
<br />10,000
<br />8
<br />91684
<br />89.75
<br />81716
<br />74.9
<br />91200
<br />80.4
<br />10,000
<br />10
<br />10,369
<br />117.75
<br />91332
<br />97.5
<br />91851
<br />104.7
<br />12,000
<br />8
<br />11,527
<br />89.75
<br />10,374
<br />75.1
<br />10,951
<br />80.5
<br />12,000
<br />10
<br />11,849
<br />117.75
<br />10,664
<br />97.7
<br />11,257
<br />104.9
<br />20,000
<br />10
<br />19,703
<br />117.75
<br />17,733
<br />98.3
<br />18,718
<br />105.4
<br />30,000
<br />10
<br />30,063
<br />118.25
<br />27,057
<br />99.1
<br />28,560
<br />106.2
<br />40,000
<br />10
<br />40,304
<br />118.25
<br />36,274
<br />99.2
<br />38,289
<br />106.3
<br />Xerxes Double -Wall Compartmented USTs Manufactured Before 9/1/2008:
<br />H. Additional Ball Float Issues (Excerpts from SWRCB Local Guidance (LG) Letter LG -150-2]
<br />➢ Ball float valves should not be used with suction piping systems or pressure delivery systems. During a
<br />product drop, as the tank fills, the ball seat restricts the flow of vapor back to the transport truck or
<br />through the tank vent. Vapors can no longer escape and are compressed inside the tank. If a ball float is
<br />used in conjunction with a suction piping system, the increased pressure in the tank can push product
<br />out through the air eliminator at the dispenser, causing a spill at the fuel island. Additionally, when ball
<br />float valves are used in conjunction with pressure delivery systems, fuel delivery could over pressurize
<br />and/or overfill the tank.
<br />➢ When using ball float valves, a valve should be installed at each tank top opening from which the tank
<br />could vent during delivery. Ball float vent valves protrude into underground storage tanks from the Stage
<br />1 vapor return riser pipe. As the tank becomes full during a product drop, the ball seat restricts the flow
<br />of vapors back to the transport truck or through the tank vent. Vapors cannot escape from the tank, and
<br />are instead compressed in the remaining ullage space. As the vapors are compressed, product flow into
<br />the tank is severely restricted. If all tank vent openings are not restricted, vapors can exit the tank and
<br />product flow will not be restricted.
<br />➢ When using a combination of ball float valves and flapper valves, the flapper valve should be set below
<br />the level of the ball float valves. If the ball float valve is installed below the flapper valve, it may interfere
<br />with the normal operation of the flapper valve. [Note: A certain amount of flow is necessary to cause the
<br />flapper to shut properly. Back pressure in the tank from a flow restrictor might cause the product delivery
<br />flow rate to drop below that level.]
<br />HMPG-025 7/7- Rev.
<br />09/20/18
<br />Size
<br />Diameter
<br />Actual
<br />Actual
<br />90%
<br />90% Height
<br />Height
<br />Tank
<br />(Gallons)
<br />(Feet)
<br />Capacity
<br />Diameter
<br />Volume
<br />(Inches)
<br />Volume
<br />(Inches)
<br />(Gallons)
<br />(Inches)
<br />(Gallons)
<br />(Gallons)
<br />Base Tank
<br />12K/8K
<br />8
<br />11,527
<br />89.75
<br />10,374
<br />75.1
<br />10,951
<br />80.5
<br />End Tank
<br />12K/8K
<br />8
<br />7,917
<br />90.25
<br />7,125
<br />1 76.1
<br />71521
<br />81.4
<br />Base Tank
<br />12K/8K
<br />10
<br />11,849
<br />117.75
<br />10,664
<br />97.7
<br />11,257
<br />104.9
<br />End Tank
<br />12K/8K
<br />10
<br />71817
<br />118.125
<br />71035
<br />99.6
<br />71426
<br />106.6
<br />H. Additional Ball Float Issues (Excerpts from SWRCB Local Guidance (LG) Letter LG -150-2]
<br />➢ Ball float valves should not be used with suction piping systems or pressure delivery systems. During a
<br />product drop, as the tank fills, the ball seat restricts the flow of vapor back to the transport truck or
<br />through the tank vent. Vapors can no longer escape and are compressed inside the tank. If a ball float is
<br />used in conjunction with a suction piping system, the increased pressure in the tank can push product
<br />out through the air eliminator at the dispenser, causing a spill at the fuel island. Additionally, when ball
<br />float valves are used in conjunction with pressure delivery systems, fuel delivery could over pressurize
<br />and/or overfill the tank.
<br />➢ When using ball float valves, a valve should be installed at each tank top opening from which the tank
<br />could vent during delivery. Ball float vent valves protrude into underground storage tanks from the Stage
<br />1 vapor return riser pipe. As the tank becomes full during a product drop, the ball seat restricts the flow
<br />of vapors back to the transport truck or through the tank vent. Vapors cannot escape from the tank, and
<br />are instead compressed in the remaining ullage space. As the vapors are compressed, product flow into
<br />the tank is severely restricted. If all tank vent openings are not restricted, vapors can exit the tank and
<br />product flow will not be restricted.
<br />➢ When using a combination of ball float valves and flapper valves, the flapper valve should be set below
<br />the level of the ball float valves. If the ball float valve is installed below the flapper valve, it may interfere
<br />with the normal operation of the flapper valve. [Note: A certain amount of flow is necessary to cause the
<br />flapper to shut properly. Back pressure in the tank from a flow restrictor might cause the product delivery
<br />flow rate to drop below that level.]
<br />HMPG-025 7/7- Rev.
<br />09/20/18
<br />
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