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TM 9-2330-272-14
4-64. PURGING TANK (Con’t).
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Start blower BEFORE inserting duct into manhole opening. This will prevent fuel vapors from entering duct and
going into blower.
Ground duct to semitrailer.
Install duct inside manhole opening Secure with tape or tie to semitrailer.
Purge tank for two hours. During purging operation, observe that air is being expelled at all valves and drain
points. Trapped fuel may prevent air from being circulated through all valves and drains. In the event air is not
coming out of a valve or drain, temporarily close all other valves and drains and observe if trapped fuel is
expelled. Reopen valves and drains.
Remove duct from manhole opening.
Shut off air supply. Wait ten minutes.
Measure explosive vapor level of tank. Take readings in several areas of tank. Readings should be 20%. lower
explosive level (LEL) or less. If any reading is above 20% LEL, resume purging operation following instructions
above.
Purge for one hour AFTER a safe reading is obtained.
Remove duct from manhole opening BEFORE shutting off blower.
Close all valves and drains. Leave manhole fill covers open. Tank is now ready to clean, repair, paint, store,
change material, or ship.
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