UNDERWAY REPLENISHMENT NWP 4-01.4 - Historic Naval Ships ...

NWP 4-01.4FLOW-THRU SADDLETYPE (B)SADDLE WHIP4-FOOT (1.2 m) HOSESECTIONFLOW-THRU SADDLETYPE (A)HOSE COUPLINGFigure 3-20. 4-Foot (1.2 m) Hose SectionsCAUTIONActuating valves too rapidly may disengageprobes or other couplings. This can causefuel spills or damage to fuel piping, valves,and fuel hoses.3.9.1.6 Blowdown and Back Suction. Once fuelingis completed, the delivery ship will determine theneed to remove fuel from the delivery hoses. Removingfuel can be done through blowdown, back suction, or acombination of the two. Blowdown is the fastestmethod of removing fuel from a delivery hose; a combinationof blowdown with back suction is the mostthorough. The combination method should be conducted,as a minimum, after the last fueling evolution(when hoses will not be used for several days), whenswitching fuel products a hose will deliver, and at othertimes the delivery ship considers necessary.3.9.1.6.1 Blowdown. Blowdown uses air to forceexcess fuel out of the delivery hose and into the receivingship’s tanks. To accomplish blowdown, the deliveryship stops pumping and closes the fuel deliveryriser valve. The delivery ship then injects low pressureair (approximately 80 psi (552 kPa)) into the fuel deliveryhose. Blowdown takes about 3 minutes to clear fuelfrom the delivery hose.CAUTION• The receiving ship must not disconnect theFAS coupling until blowdown is completed.Attempting to disconnect the FAS couplingmay cause fuel spills or damage to fuel pipingor fuel hoses.• The receiving ship must leave valves andtank vents open during blowdown so thatfuel and air may move through the fuel hose.Failure to do so may cause fuel spills ordamage to fuel piping or fuel hoses.3-25 ORIGINAL