UFC 3-460-03
21 JANUARY 2003
turn the BPCV CRD adjusting stem clockwise to increase pressure and counterclockwise to
decrease pressure.
6.4.15. Defuel/Flush Valve (D/FV) (58AF-9-1):
6.4.15.1. This valve (Figure 6.8) is controlled by two different solenoids: solenoid A controls the
defuel portion of the main valve and holds the valve closed any time a fueling pump is running;
solenoid B controls the flush portion of the main valve and functions only when the system is
placed in the flush mode. When the lead pump de-energizes, solenoid A energizes, allowing the
valve to open and drop the system pressure to 80 psi. While the system is in the idle position, the
valve will open to allow defueling when the hydrant loop pressure rises above 80 psi. Defueling is
conducted by using the HSV to pump the fuel off the plane and force the fuel into the hydrant loop
at a rate of 1135 liters per minute (300 gallons per minute) and 165 psi. 165 psi will overcome the
80-psi setting of the 58AF-9-1 D/FV and the valve opens. Solenoid B energizes only when the
system is placed in the flush mode. The reason for system flushing is to move fuel through the
pipeline as fast as possible and clean the loop. With the system in the flush mode, energize all
available fueling pumps by placing the pumps' Hand-Off Auto switch in the "Hand" position to get
the maximum meter-per-second (foot-per-second) flow in the hydrant loop. The 58AF-9-1 D/FV
valve opens, allowing the maximum amount of fuel to flow through the system.
Figure 6.8. D/FV (58AF-9-1).
6.4.15.2. Valve Setting. Close the manual valve upstream of the 58AF-3, Pressure Control Valve
(PCV) to ensure system pressure does not flow through the valve while adjusting the D/FV.
Bottom the CRL on the D/FV. Place the system in automatic mode and pressurize the system.
When the system shuts down, turn the CRL adjusting stem on the D/FV counterclockwise until the
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