4-72. PRECHECK SYSTEM MAINTENANCE.
Removal of Check Valve
Removal of Precheck Valve
Installation of Check Valve
Installation of Precheck Valve
Removal of Precheck Tubing
Removal of Pressure Gage
Installation of Precheck Tubing
Installation of Pressure Gage
General Safety Instructions:
When working inside tank, always provide
adequate forced air ventilation at the man-
Tank purged if replacing precheck
hole opening with air directed into com-
system components inside tank.
partment' where work is being performed.
NEVER work alone inside a tank: a second
person must be stationed at the manhole
opening. The person inside the tank must
have a safety line and harness on in case of
emergency for rescue operations.
Tool kit, general mechanic's
REMOVAL OF PRECHECK VALVE
(1) Remove two nuts (9) lock-
washers (10), screws (2), and
washers (1) and remove pre-
check valve (8) from mounting to
shelf of cabinet (11). Discard