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TM 10-3835-231-13
Section VI. UNIT MAINTENANCE PROCEDURES
4-33. GENERAL.
The procedures in this section have been arranged in the order in which the items appear in the unit (O) maintenance
level column on the Maintenance Allocation Chart (MAC) which is provided in Appendix B. Step-by-step procedures have
been provided for all action authorized to be performed by unit maintenance in the order in which they appear on the
MAC.
4-34. DE-PRESSURIZING AND DRAINING BEFORE MAINTENANCE REMOVAL OF COMPONENTS.
WARNING
DE-PRESSURIZE AND DRAIN FUEL
Before disconnecting or opening any equipment or system, be sure to de-
pressurize and drain it first. Serious personnel injury and fire hazards can result if
you do not.
WARNING
FUEL SPLASHES AND SPILLS
Splashes and spills can cause eye injury and skin irritation. Wear face shield ad
approved gloves.
WARNING
FUEL SPILLS
Spills can result in saturated soil and cause a potential fire hazard.
a.
A system is generally de-pressurized by opening the valves in the line of flow leading to a fabric collapsible tank.
The valves upstream of the section to be de-pressurized are left closed.
b.
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 de-pressurized, 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 de-pressurizing of the particular item.
c.
The fuel dispensing assembly or the optional tanker-truck unloading system can be de-pressurized by opening
the valves in the flow path to the tanker-truck after the associated pump has been shut down and blocked in.
d.
When a fuel transfer has been completed the valve in the applicable flow line that is furthest upstream (closest to
the source of fuel under pressure) should 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 de-pressurized.
e.
When a system, or a portion of a system, must be drained for maintenance the system must be de-pressurized
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.
NOTE
For disposal of contaminated fuel refer to FM 10-69.
4-57
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