4-9. GENERAL MAINTENANCE PROCEDURES -Continued
To prevent any contamination from new hose assembly, blow out hose assembly using
compressed air. Rinse inside of hose with hot water. Do not allow water temperature to exceed
180 deg. F (82 deg. C). Using compressed air, blow out all water from hose assembly.
If new hose assembly is not going to be installed immediately after installing fittings, cap both
ends to keep hose clean.
f. Locating Air Leaks in Water/Foam Piping. The following procedure describes a method of locating air leaks.
Attach suction caps to all suction ports.
Close all discharge and drain valves.
Open priming valve and operate primer until vacuum gauge indicates 20 to 22 in (51 to 56 mm) Hg.
If primer fails to draw specified vacuum, prime may be defective
or air leaks are too large for primer to handle.
Close primer valve and shut off primer. If vacuum drops more than 10 in (25 mm) Hg in 10 minutes,
serious air leaks are indicated. With engine stopped air leaks are frequently loud enough to be heard.
If leaks cannot be heard, apply engine oil to the suspected points and watch for break in oil film or oil
being drawn into pump or piping.
Connect suction hose to hydrant or auxiliary pump.
When testing for leaks, 1 00 psi (689 kPa) water pressure is
sufficient. Do not exceed recommended pressures. Damage to
components may result.
Open one discharge valve and run in water until pump is completely filled and all air expelled.
Close discharge valves, apply pressure to system and watch for leaks.
If the pump has not been operated for several weeks, packings may be dried out. Close
discharge and drain valves and cap suction ports. Operate primer to build up a strong vacuum in
pump, run pump slowly, and apply engine oil to impeller shaft near packing gland. Also be sure
packing is adjusted properly.
Fasteners. Replace any bolt, screw, nut, or fitting that has damaged threads. Inspect tapped holes for
damage. If fitting cannot be retapped with next oversize screw or stud, chasing the threads with proper
size tap or die may cure the problem.
Gaskets. Never reuse old gaskets except in an absolute emergency. Always ensure correct gasket is
being used as replacement by fitting dry.