Dover Wilden P8 Original Series, Engineering, Operation & Maintenance

Page: 27 / 52

WIL-10320-E-08
25 WILDEN PUMP & ENGINEERING, LLC
S U G G E S T E D O P E R A T I O N & M A I N T E N A N C E
T R O U B L E S H O O T I N G
OPERATION: The P8 and PX8 are pre-lubricated, and
do not require in-line lubrication. Additional lubrication
will not damage the pump, however if the pump is
heavily lubricated by an external source, the pump’s
internal lubrication may be washed away. If the pump
is then moved to a non-lubricated location, it may need
to be disassembled and re-lubricated as described in
the ASSEMBLY/DISASSEMBLY INSTRUCTIONS.
Pump discharge rate can be controlled by limiting the
volume and/or pressure of the air supply to the pump.
An air regulator is used to regulate air pressure. A needle
valve is used to regulate volume. Pump discharge rate
can also be controlled by throttling the pump discharge
by partially closing a valve in the discharge line of
the pump. This action increases friction loss which
reduces flow rate. (See Section 5.) This is useful when
the need exists to control the pump from a remote
location. When the pump discharge pressure equals
or exceeds the air supply pressure, the pump will
stop; no bypass or pressure relief valve is needed, and
pump damage will not occur. The pump has reached a
“deadhead” situation and can be restarted by reducing the fluid discharge pressure or increasing the air inlet
pressure. The Wilden P8 and PX8 pumps run solely on
compressed air and do not generate heat, therefore
your process fluid temperature will not be affected.
MAINTENANCE AND INSPECTIONS:
Since each
application is unique, maintenance schedules may
be different for every pump. Frequency of use, line
pressure, viscosity and abrasiveness of process fluid
all affect the parts life of a Wilden pump. Periodic
inspections have been found to offer the best
means for preventing unscheduled pump downtime.
Personnel familiar with the pump’s construction and
service should be informed of any abnormalities that
are detected during operation.
RECORDS: When service is required, a record should
be made of all necessary repairs and replacements.
Over a period of time, such records can become a
valuable tool for predicting and preventing future
maintenance problems and unscheduled downtime. In
addition, accurate records make it possible to identify
pumps that are poorly suited to their applications.
Pump will not run or runs slowly.
1. Ensure that the air inlet pressure is at least 0.4 bar
(5 psig) above startup pressure and that the differential
pressure (the difference between air inlet and liquid
discharge pressures) is not less than 0.7 bar (10 psig).
2. Check air inlet filter for debris (see SUGGESTED
INSTALLATION).
3. Check for extreme air leakage (blow by) which
would indicate worn seals/bores in the air valve,
pilot spool and main shaft.
4. Disassemble pump and check for obstructions
in the air passageways or objects which would
obstruct the movement of internal parts.
5. Check for sticking ball check valves. If material being
pumped is not compatible with pump elastomers,
swelling may occur. Replace ball check valves and
seals with proper elastomers. Also, as the check
valve balls wear out, they become smaller and can
become stuck in the seats. In this case, replace balls
and seats.
6. Check for broken inner piston which will cause the
air valve spool to be unable to shift.
7. Remove plug from pilot spool exhaust.
Pump runs but little or no product flows.
1. Check for pump cavitation; slow pump speed
down to allow thick material to flow into liquid
chambers.
2. Verify that vacuum required to lift liquid is not
greater than the vapor pressure of the material
being pumped (cavitation).
3. Check for sticking ball check valves. If material being
pumped is not compatible with pump elastomers,
swelling may occur. Replace ball check valves and
seats with proper elastomers. Also, as the check
valve balls wear out, they become smaller and can
become stuck in the seats. In this case, replace balls
and seats.
Pump air valve freezes.
1. Check for excessive moisture in compressed
air. Either install a dryer or hot air generator for
compressed air. Alternatively, a coalescing filter
may be used to remove the water from the
compressed air in some applications.
Air bubbles in pump discharge.
1. Check for ruptured diaphragm.
2. Check tightness of outer pistons (refer to Section 7).
3. Check tightness of fasteners and integrity of O-rings
and seals, especially at intake manifold.
4. Ensure pipe connections are airtight.
Product comes out air exhaust.
1. Check for diaphragm rupture.
2. Check tightness of outer pistons to shaft.