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TM 10-3835-231-13
2-6. OPERATING PROCEDURES. - continued
v.
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.
WARNING
PRESSURIZED SYSTEM
Do not break (open) any flanges or open any couplings until the system is
depressurized at that location. Injury can result.
(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 left closed.
(2)
Individual pieces of equipment such as the strainer in the meter skid 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.
(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 tanker-truck after the associated pump has been shut down and
blocked in.
(4)
Close valves 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.
(5)
When a system, or a portion of a system, must be drained for maintenance, it must be depressurized first.
Obtain appropriate containers to hold the drained fuel for disposal. The Closure at the lowest point should
be opened first and the hose drained into the container(s). A closure at the highest point should be opened
to allow complete drainage.
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