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4-16 Fuel Transfers- Cont'd.
1.
Open valves V6J, V71, VI J, V121, V14J, V18J, V321, V31) and V21J.
2.
Although the drawings and the P&ID in this manual show one possible hook-up, numerous combinations can be
made, depending on hoseline availability and the service required.
4-17 Depressurizing and Draining System
After the TPT is commissioned and placed in operation it will be necessary from time to time to depressurize and drain
various parts of the system for maintenance or disassembly. Throughout the operating and maintenance instructions of
the manual the reader is warned to depressurize the system before breaking (opening) flanges, couplings, and other
closures. This is to avoid spills or sprays of fuel that can injure personnel or cause a fire hazard. The following describes
procedures recommended for depressurization and draining.
4-17.1 A system is generally depressurized by opening the valves in the line of flow leading to a fabric collapsible tank.
The valves upstream of the section to be depressurized are, of course, left dosed. For example; (referring to P&ID Fig.
2-1) if it is necessary to depressurize the hose system leading from the switching manifold to tank T1I in the secondary
module of the jet fuel unit to work on or replace valve V2D, the procedure is to leave the following valves closed: VJ,
VI51, V116, V81, V 19J. The following valves are opened: V2J, V31, V4J, V5J. The system will then depressurize into
tank T1J.
4-17.2 Individual pieces of equipment such as the strainer in the meter strainer assembly, the filter separators, and the
hose line pumps have individual vents and drains. After the system has been depressurized, or that piece of equipment
blocked in, the vents and drains on the equipment should be opened before that particular item is worked on. This will
assure depressurizing of the particular item.
4-17.3 The fuel dispensing assembly or the optional tanker-truck unloading system can be depressurized by opening the
valves in the flow path to the vehicle after the associated pump has been shut down an blocked in.
4-17.4 As a standard practice it is recommended that when a fuel transfer has been completed that the valve in the
applicable flow line that is furthest upstream (closest to the source of fuel under pressure) be closed first and sequentially
followed by the closing of the valves downstream. This will avoid the block in of fuel under pressure and thus enhance
the safety of the system. A line closed off in this manner will be depressurized.
4-17.5 When a system, or a portion of a system, must be drained for maintenance the system must be depressurized
first. Arrangements should be made for containers to hold the drained fuel for subsequent disposal. The closure(s)
(flanges or couplings) at the lowest point(s) should then be opened first and the hose drained into the container(s). A
closure at the highest point should then be opened to allow complete drainage.
SECTION IV - OPERATIONS UNDER UNUSUAL CONDITIONS
4-18 General
Operating under severe environmental conditions such as unusually cold weather, unusually hot weather, or in blowing
sand and dust requires special precautions. These precautions are outlined below.
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