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When removing a worn valve seat, use the Gardner-
Denver puller powered with a hydraulic jack. Be careful
to chain or tie the jack down as it will jump violently
when the valve seat lets go. If it becomes necessary to
resort to the use of heat or a cutting torch to remove a
valve seat, the services of a man experienced in these
operations is necessary.
Before putting new seats in the pump, the tapered bore
in the valve seat deck of the cylinder must be
thoroughly cleaned with a wire brush. Wire brush
should be used around the bore rather than up and
down. Wipe the bore clean and do not use oil or
grease. The bore must be clean and dry or seat may
not seat properly. The valve seat tapered surface must
be cleaned and dry before assembling in cylinder deck.
Place the new seat in the bore. Use an old valve
bumper or a block of hard wood and drive with a
sledge to a snug initial fit. The pressure load on the
valve in operation will drive the seat home. Never
reuse an old seat once it has been removed from a
cylinder, as it may not fit solidly in the valve deck.
Replace the valve guide or valve guide bushings if
worn. Replace the valve spring if it is worn, corroded,
distorted, or below normal tension. Valves are provided
with stainless steel springs for maximum operating life.
A broken spring will cause rapid wear of valve guides
and should be replaced. It will also cause wear on
suction valve guide mounting lugs inside the valve
chamber (cylinder).
Do not put a used valve assembly on a new seat
unless it is in practically a new condition. Be sure to
replace a doubtful insert to protect seat and bumper.
It requires experience and judgment to determine if
valve parts should be replaced or not. Valves are
cheaper than downtime.
When installing valves, wipe all sealing surfaces clean,
put the gasket carefully in place in the valve chamber
and install cover plate. Be sure gasket is not twisted or
extruded. Tighten valve cover lock securely by using a
bar and hammer.
The life of the valves will be lengthened if the mud
tanks are kept clean. In may cases foreign objects are
caught under the valves, thereby holding them open
and causing rapid cutting of the seats and valves.
SUCTION STRAINER
- A suction strainer is
recommended for the suction line of every pump to
protect the valves.
The current PZ series and PXL pumps are not
equipped with a suction strainer. A commercial
strainer, however, may be installed in the suction line
ahead of the pump.
The early PZJ pumps were equipped with a perforated
metal strainer inside the suction manifold. This strainer
can be removed from the end opposite the suction line
for inspection and cleaning. Strainer should be
checked if the pump starts to run rough, with violent
discharge pulsations. One or more cylinders may have
their suction obstructed by debris in the strainer.