Wilden Original Series Troubleshooting guide

P.025
WIL-10090-E-04
REPLACES WIL-10090-E-03
Original™Series PLASTIC Pumps
Engineering
Operation &
Maintenance
Simplify your process

SECTION 1 CAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
SECTION 2 PUMP DESIGNATION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
SECTION 3 HOW IT WORKS (PUMP & AIR SYSTEMS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
SECTION 4 DIMENSIONAL DRAWING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
SECTION 5 PERFORMANCE CURVES
A. P.025 PLASTIC Rubber-Fitted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
B. P.025 PLASTICTPE-Fitted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
B. P.025 PLASTIC PTFE-Fitted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
B. Suction Lift Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
SECTION 6 SUGGESTED INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Suggested Operation and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
SECTION 7 PUMP DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Air Valve/Cleaning & Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
SECTION 8 EXPLODED VIEW & PARTS LISTING
P.025 PLASTIC Rubber/TPE-Fitted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
P.025 PLASTIC PTFE-Fitted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
SECTION 9 ELASTOMER OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
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U.S. Clean Air Act
Amendments of 1990
TABLE OF CONTENTS

1WILDEN PUMP & ENGINEERING, LLC
WIL-10090-E-04
TEMPERATURE LIMITS:
Polypropylene 0°C to 79°C +32°F to 175°F
PVDF –12°C to 107°C +10°F to 225°F
Buna-N –12.2°C to 82.2°C +10°F to +180°F
Viton®–40°C to 176.7°C –40°F to +350°F
Wil-Flex™ –40°C to 107.2°C –40°F to +225°F
PTFE +4.4°C to 104.4°C +40°F to +220°F
CAUTION: When choosing pump materials, be
sure to check the temperature limits for all wetted
components. Example: Viton®has a maximum
limit of 176.7°C (350°F) but polypropylene has a
maximum limit of only 79°C (175°F ).
CAUTION: Maximum temperature limits are based
upon mechanical stress only. Certain chemicals
will significantly reduce maximum safe operating
temperatures. Consult engineering guide for
chemical compatibility and temperature limits.
CAUTION: Always wear safety glasses when
operating pump. If diaphragm rupture occurs,
material being pumped may be forced out air
exhaust.
WARNING: Prevention of static sparking — If
static sparking occurs, fire or explosion could
result. Pump, valves, and containers must be
properly grounded when handling flammable
fluids and whenever discharge of static electricity
is a hazard.
CAUTION: Do not exceed 8.6 bar (125 psig) air
supply pressure.
CAUTION: Before any maintenance or repair is
attempted, the compressed air line to the pump
should be disconnected and all air pressure
allowed to bleed from pump. Disconnect all intake,
discharge and air lines. Drain the pump by turning
it upside down and allowing any fluid to flow into
a suitable container.
CAUTION: Blow out air line for 10 to 20 seconds
before attaching to pump to make sure all pipe line
debris is clear. Use an in-line air filter. A 5µ (micron)
air filter is recommended.
NOTE: Tighten clamp bands and retainers
prior to installation. Fittings may loosen during
transportation.
NOTE: When installing PTFE diaphragms, it is
important to tighten outer pistons simultaneously
(turning in opposite directions) to ensure tight fit.
NOTE: Before starting disassembly, mark a line
from each liquid chamber to its corresponding air
chamber. This line will assist in proper alignment
during reassembly.
CAUTION: Verify the chemical compatibility of
the process and cleaning fluid to the pump’s
component materials in the Chemical Resistance
Guide. (see E4).
NOTE: Plastic series pumps are made of virgin
plastic and are not UV stabilized. Direct sunlight
for prolonged periods can cause deterioration of
plastics.
CAUTION: The P.025 pump is not submersible.
Section 1
CAUTIONS—READ FIRST!

2
WILDEN PUMP & ENGINEERING, LLC WIL-10090-E-04
P.025 ORIGINAL™
PLASTIC
6 mm (1/4") Pump
Maximum Flow Rate:
18.2 lpm (4.8 gpm)
MATERIAL CODES
WETTED PARTS & OUTER PISTON
KK = PVDF / PVDF
KZ = PVDF / NO PISTON
PP = POLYPROPYLENE /
POLYPROPYLENE
PZ = POLYPROPYLENE /
NO PISTON
CENTER SECTION
LL = ACETAL
PP = POLYPROPYLENE
AIR VALVE
L = ACETAL
P = POLYPROPYLENE
DIAPHRAGMS
BNS = BUNA-N (Red Dot)
TNL = PTFE W/ NEOPRENE
BACK-UP O-RING,
IPD (White)
WFS = WIL-FLEX™ [Santoprene®
(Orange Dot)]
VALVE BALL
TF = PTFE (White)
VALVE SEAT
K = PVDF
P = POLYPROPYLENE
VALVE SEAT O-RING
BN = BUNA-N (Red Dot)
TV = PTFE ENCAP. VITON®
WF = WIL-FLEX™ [Santoprene®]
SPECIALTY CODES
0502 PFA coated hardware
0512 Adapter block, no muffler, Pro-Flo®,
center section
LEGEND
P.025 / XXXXX / XXX / XX / XXX / XXXX
O-RINGS
MODEL VALVE SEAT
VALVE BALLS
DIAPHRAGMS
AIR VALVE
CENTER SECTION
WETTED PARTS & OUTER PISTON
SPECIALTY
CODE
(if applicable)
Viton®is a registered trademark of Dupont Dow Elastomers.
Section 2
WILDEN PUMP DESIGNATION SYSTEM

3WILDEN PUMP & ENGINEERING, LLC
The Wilden diaphragm pump is an air-operated, positive displacement, self-priming pump. These drawings show flow pattern through
the pump upon its initial stroke. It is assumed the pump has no fluid in it prior to its initial stroke.
FIGURE 1 The air valve directs pressurized air to the back
side of diaphragm A. The compressed air is applied directly
to the liquid column separated by elastomeric diaphragms.
The diaphragm acts as a separation membrane between the
compressed air and liquid, balancing the load and removing
mechanical stress from the diaphragm. The compressed
air moves the diaphragm away from the center block of
the pump. The opposite diaphragm is pulled in by the shaft
connected to the pressurized diaphragm. Diaphragm B is
on its suction stroke; air behind the diaphragm has been
forced out to the atmosphere through the exhaust port
of the pump. The movement of diaphragm B toward the
center block of the pump creates a vacuum within chamber
B. Atmospheric pressure forces fluid into the inlet manifold
forcing the inlet valve ball off its seat. Liquid is free to move
past the inlet valve ball and fill the liquid chamber (see
shaded area).
FIGURE 2 When the pressurized diaphragm, diaphragm
A, reaches the limit of its discharge stroke, the air valve
redirects pressurized air to the back side of diaphragm
B. The pressurized air forces diaphragm B away from the
center block while pulling diaphragm A to the center block.
Diaphragm B is now on its discharge stroke. Diaphragm B
forces the inlet valve ball onto its seat due to the hydraulic
forces developed in the liquid chamber and manifold of the
pump. These same hydraulic forces lift the discharge valve
ball off its seat, while the opposite discharge valve ball is
forced onto its seat, forcing fluid to flow through the pump
discharge. The movement of diaphragm A toward the center
block of the pump creates a vacuum within liquid chamber
A. Atmospheric pressure forces fluid into the inlet manifold
of the pump. The inlet valve ball is forced off its seat allowing
the fluid being pumped to fill the liquid chamber.
FIGURE 3 At completion of the stroke, the air valve again
redirects air to the back side of diaphragm A, which starts
diaphragm B on its exhaust stroke. As the pump reaches
its original starting point, each diaphragm has gone through
one exhaust and one discharge stroke. This constitutes
one complete pumping cycle. The pump may take several
cycles to completely prime depending on the conditions of
the application.
RIGHT STROKE MID STROKE LEFT STROKE
The Pro-Flo®patented air distribution sys-
tem incorporates three moving parts: the
air valve spool, the pilot spool, and the
main shaft/diaphragm assembly. The heart
of the system is the air valve spool and
air valve. As shown in Figure 1, this valve
design incorporates an unbalanced spool.
The smaller end of the spool is pressurized
continuously, while the large end is alter-
nately pressurized and exhausted to move
the spool. The spool directs pressurized
air to one chamber while exhausting the
other. The air causes the main shaft/
diaphragm assembly to shift to one side
— discharging liquid on one side and
pulling liquid in on the other side. When
the shaft reaches the end of its stroke, it
actuates the pilot spool, which pressur-
izes and exhausts the large end of the
air valve spool. The pump then changes
direction and the same process occurs in
the opposite direction, thus reciprocating
the pump.
WIL-10090-E-04
Figure 1
Section 3
HOW IT WORKS
HOW IT WORKS—AIR DISTRIBUTION SYSTEM

4
WILDEN PUMP & ENGINEERING, LLC WIL-10090-E-04
DIMENSIONS
ITEM METRIC (mm) STANDARD (inch)
A 145 5.7
B 25 1.0
C 94 3.7
D 140 5.5
E 163 6.4
F 56 2.2
G 30 1.2
H 30 1.2
J 114 4.5
K 61 2.4
L 74 2.9
M 53 2.1
N 64 2.5
P Ø5 Ø.2
Section 4
DIMENSIONAL DRAWINGS
P.025 M e t a l
REV. B

5WILDEN PUMP & ENGINEERING, LLC
Height....................................163 mm (6.4")
Width.....................................145 mm (5.7")
Depth ....................................115 mm (4.5")
Est. Ship Weight.....
Polypropylene 1.4 kg (3 lbs)
PVDF 1.4 kg (3 lbs)
Air Inlet..................................... 3 mm (1/8")
Inlet.......................................... 6 mm (1/4")
Outlet ....................................... 6 mm (1/4")
Suction Lift ...........................2.74 m Dry (9')
9.45 m Wet (31')
Displacement per
Stroke .........................0.02 l (0.004 gal.)1
Max. Flow Rate...............18.1 lpm (4.8 gpm)
Max. Size Solids .................. 0.4 mm (1/64")
1Displacement per stroke was calculated at 4.8 bar
(70 psig) air inlet pressure against a 2 bar (30 psig)
head pressure.
Example: To pump 7.6 lpm (2 gpm) against
a discharge pressure head of 2 bar (30 psig)
requires 4.1 bar (60 psig) and 2.0 Nm3/h
(1.2 scfm) air consumption. (See dot on
chart.)
Caution: Do not exceed 8.6 bar (125 psig) air
supply pressure.
Flow rates indicated on chart were determined by pumping water.
For optimum life and performance, pumps should be specified so that daily operation parameters
will fall in the center of the pump performance curve.
Height....................................163 mm (6.4")
Width.....................................145 mm (5.7")
Depth ....................................115 mm (4.5")
Est. Ship Weight.....
Polypropylene 1.4 kg (3 lbs)
PVDF 1.4 kg (3 lbs)
Air Inlet..................................... 3 mm (1/8")
Inlet.......................................... 6 mm (1/4")
Outlet ....................................... 6 mm (1/4")
Suction Lift .........................3.05 m Dry (10')
8.84 m Wet (29')
Displacement per
Stroke ....................... 0.02 l gal. (0.005)1
Max. Flow Rate...............18.1 lpm (4.8 gpm)
Max. Size Solids .................. 0.4 mm (1/64")
1Displacement per stroke was calculated at 4.8 bar
(70 psig) air inlet pressure against a 2 bar (30 psig)
head pressure.
Example: To pump 7.6 lpm (2 gpm) against
a discharge pressure head of 2 bar (30 psig)
requires 4.1 bar (60 psig) and 2.0 Nm3/h
(1.2 scfm) air consumption. (See dot on
chart.)
Caution: Do not exceed 8.6 bar (125 psig) air
supply pressure.
Flow rates indicated on chart were determined by pumping water.
For optimum life and performance, pumps should be specified so that daily operation parameters
will fall in the center of the pump performance curve.
WIL-10090-E-04
Section 5A
PERFORMANCE
P.025 PLASTIC
RUBBER-FITTED
P.025 PLASTIC
TPE-FITTED

6
WILDEN PUMP & ENGINEERING, LLC
Height....................................163 mm (6.4")
Width.....................................145 mm (5.7")
Depth ....................................115 mm (4.5")
Est. Ship Weight.....
Polypropylene 1.4 kg (3 lbs)
PVDF 1.4 kg (3 lbs)
Air Inlet..................................... 3 mm (1/8")
Inlet.......................................... 6 mm (1/4")
Outlet ....................................... 6 mm (1/4")
Suction Lift ...........................2.44 m Dry (8')
8.84 m Wet (29')
Displacement per
Stroke ...................... 0.02 l (0.005 gal.)1
Max. Flow Rate...............18.1 lpm (4.8 gpm)
Max. Size Solids .................. 0.4 mm (1/64")
1Displacement per stroke was calculated at 4.8 bar
(70 psig) air inlet pressure against a 2 bar (30 psig)
head pressure.
Example:To pump 8.7 lpm (2.3 gpm) against
a discharge pressure head of 2 bar (30 psig)
requires 4.1 bar (60 psig) and 2.4 Nm3/h
(1.4 scfm) air consumption. (See dot on
chart.)
Caution: Do not exceed 8.6 bar (125 psig) air
supply pressure.
Flow rates indicated on chart were determined by pumping water.
For optimum life and performance, pumps should be specified so that daily operation parameters
will fall in the center of the pump performance curve.
Suction lift curves are calibrated for pumps operating at
1,000’ (305 m) above sea level. This chart is meant to be a
guide only. There are many variables which can affect your
pump’s operating characteristics. The number of intake
and discharge elbows, viscosity of pumping fluid, elevation
(atmospheric pressure) and pipe friction loss all affect the
amount of suction lift your pump will attain.
WIL-10090-E-04
P.025 PLASTIC
PTFE-FITTED
PERFORMANCE
P.025 PLASTIC
Section 5B SUCTION LIFT CURVE

7WILDEN PUMP & ENGINEERING, LLC
The Pro-Flo®model P.025 has a 6 mm (1/4") inlet and 6 mm
(1/4") outlet and is designed for flows to 18.7 lpm (4.8 gpm).
The P.025 Plastic pump is manufactured with wetted parts
of pure, unpigmented PVDF or polypropylene. The center
section of the P.025 Plastic is constructed of virgin Acetal
or polypropylene. A variety of diaphragms and o-rings are
available to satisfy temperature, chemical compatibility,
abrasion and flex concerns.
The suction pipe size should be at least 6 mm (1/4") diameter
or larger if highly viscous material is being pumped. The
suction hose must be non-collapsible, reinforced type as
the P.025 is capable of pulling a high vacuum. Discharge
piping should be at least 6 mm (1/4"); larger diameter can
be used to reduce friction losses. It is critical that all fittings
and connections are airtight or a reduction or loss of pump
suction capability will result.
INSTALLATION: Months of careful planning, study,
and selection efforts can result in unsatisfactory pump
performance if installation details are left to chance.
Premature failure and long term dissatisfaction can be
avoided if reasonable care is exercised throughout the
installation process.
LOCATION: Noise, safety, and other logistical factors usually
dictate that “utility” equipment be situated away from the
production floor. Multiple installations with conflicting
requirements can result in congestion of utility areas, leaving
few choices for siting of additional pumps.
Within the framework of these and other existing conditions,
every pump should be located in such a way that four
key factors are balanced against each other to maximum
advantage.
1. ACCESS: First of all, the location should be accessible.
If it’s easy to reach the pump, maintenance personnel will
have an easier time carrying out routine inspections and
adjustments. Should major repairs become necessary, ease
of access can play a key role in speeding the repair process
and reducing total downtime.
2. AIR SUPPLY: Every pump location should have an air
line large enough to supply the volume of air necessary to
achieve the desired pumping rate (see pump performance
chart). Use air pressure up to a maximum of 8.6 bar (125
psig) depending on pumping requirements.
Sound levels are reduced below OSHA specifications using
the standard Wilden muffler element.
3. ELEVATION: Selecting a site that is well within the pump’s
dynamic lift capability will assure that loss-of-prime troubles
will be eliminated. In addition, pump efficiency can be adversely
affected if proper attention is not given to site location.
4. PIPING: Final determination of the pump site should not
be made until the piping problems of each possible location
have been evaluated. The impact of current and future
installations should be considered ahead of time to make
sure that inadvertent restrictions are not created for any
remaining sites.
The best choice possible will be a site involving the shortest
and straightest hook-up of suction and discharge piping.
Unnecessary elbows, bends, and fittings should be avoided.
Pipe sizes should be selected so as to keep friction losses
within practical limits. All piping should be supported
independently of the pump. In addition, the piping should be
aligned so as to avoid placing stresses on the pump fittings.
Flexible hose can be installed to aid in absorbing the forces
created by the natural reciprocating action of the pump. If the
pump is to be bolted down to a solid location, a mounting
pad placed between the pump and the foundation will assist
in minimizing pump vibration. Flexible connections between
the pump and rigid piping will also assist in minimizing
pump vibration. If quick-closing valves are installed at
any point in the discharge system, or if pulsation within a
system becomes a problem, a Wilden SD1⁄2 Equalizer®surge
dampener should be installed to protect the pump, piping
and gauges from surges and water hammer.
When pumps are installed in applications involving flooded
suction or suction head pressures, a gate valve should be
installed in the suction line to permit closing of the line for
pump service.
The P.025 cannot be used in submersible applications.
If the pump is to be used in a self-priming application, be
sure that all connections are airtight and that the suction lift is
within the model’s ability. Note: Materials of construction and
elastomer material have an effect on suction lift parameters.
Please consult Wilden distributors for specifics.
Pumps in service with a positive suction head are most
efficient when inlet pressure is limited to 0.4–0.7 bar (7–10
psig). Premature diaphragm failure may occur if positive
suction is 0.7 bar (10 psig) and higher.
THE MODEL P.025 WILL PASS 0.4 MM (1/64”) SOLIDS.
WHENEVER THE POSSIBILITY EXISTS THAT LARGER SOLID
OBJECTS MAY BE SUCKED INTO THE PUMP, A STRAINER
SHOULD BE USED ON THE SUCTION LINE.
CAUTION: DO NOT EXCEED 8.6 BAR (125 PSIG) AIR SUPPLY
PRESSURE.
BLOW OUT AIR LINE FOR 10 TO 20 SECONDS BEFORE
ATTACHINGTO PUMPTO MAKE SURE ALL PIPE LINE DEBRIS
IS CLEAR.
The Pro-Flo®pump is not submersible.
WIL-10090-E-04
Section 6
SUGGESTED INSTALLATION

8
WILDEN PUMP & ENGINEERING, LLC
For best results, the pumps should use an air filter and regula-
tor. The use of an air filter before the pump will insure that the
majority of any pipeline contaminants will be eliminated. The
P.025 is permanently lubricated, and does 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 (preferred meth-
od). A regulator is used to regulate air pressure. A needle valve
is used to regulate air volume. Pump discharge rate can also
be controlled by throttling the pump discharge by installing a
valve in the discharge line of the pump. 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. When
operation is controlled by a solenoid valve in the air line, two-
way or three-way valves may be used. Pumping volume can
be set by counting the number of strokes per minute.
INSPECTIONS: 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 pre-
venting future maintenance problems and unscheduled down-
time. In addition, accurate records make it possible to identify
pumps that are poorly suited to their applications.
AIR-OPERATED PUMPS: To stop the pump from operating in an
emergency situation, simply close the “shut-off” valve (user supplied)
installed in the air supply line. A properly functioning valve will stop the
air supply to the pump, therefore stopping output. This shut-off valve
should be located far enough away from the pumping equipment such
that it can be reached safely in an emergency situation.
NOTE: In the event of a power failure, the shutoff valve should be closed,
if the restarting of the pump is not desirable once power is regained.
WIL-10090-E-04
SUGGESTED INSTALLATION
SUGGESTED OPERATION & MAINTENANCE

9WILDEN PUMP & ENGINEERING, LLC
Pump will not run or runs slowly.
1. Ensure that the air inlet pressure is at least 5 psig above
startup pressure and that the differential pressure (the
difference between inlet and discharge pressures) is not
less than 10 psig.
2. Check air inlet filter for debris (see recommended instal-
lation).
3. Check for extreme air leakage which would indicate
worn out seals/bores.
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, swell-
ing 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.
Pump runs but little or no product flows.
1. Check for pump cavitation; slow pump speed down to
match thickness of material being pumped.
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, swell-
ing 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.
4. Ensure that all suction connections are tight, especially
lower valve ball retainers.
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.
3. Check tightness of clamp bands 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 pistons to shaft.
Pump rattles.
1. Create false discharge head or suction lift.
WIL-10090-E-04
TROUBLESHOOTING

10
WILDEN PUMP & ENGINEERING, LLC
Step 2. Figure 2
Remove top retainer with 1/4” socket wrench.
Step 3. Figure 3
Inspect the ball retainer, retainer o-ring, and valve ball. If
swelling, cracking or other damage is apparent, these parts
must be replaced with genuine Wilden parts.
CAUTION: Before any maintenance or repair is attempted,
the compressed air line to the pump should be disconnected
and all air pressure allowed to bleed from pump. Disconnect
all intake, discharge, and air lines. Drain the pump by turning
it upside down and allowing any fluid to flow into a suitable
container. Wetted flushing of parts may be required prior to
handling.
The Wilden model P.025 (Figure 1) is an air-operated, double-
diaphragm pump with all wetted parts of polypropylene or
PVDF. The single-piece center section, consisting of center
block and air chambers, is molded from Acetal or polypro-
pylene. All fasteners and hardware are stainless steel. The air
valve is manufactured of Acetal or polypropylene. All o-rings
used in the pump are of special materials and should only be
replaced with factory-supplied parts.
To expedite parts ordering, please find an exploded view of the
P.025 model at the back of this manual.
PLEASE read all directions before starting disassembly.
TOOLS REQUIRED:
5/32” Hex Key (Allen wrench)
7/16” Wrench or Socket (Qty. 2)
5/16”Wrench
3/8” Wrench
1/4” Socket Drive
O-ring Pick
3/16” Rod or Equivalent
DISASSEMBLY:
Step 1.
Before actual disassembly is started, turn pump upside
down and drain all liquid trapped in the pump into a suitable
container. Be sure to use proper caution if liquid is corrosive
or toxic.
WIL-10090-E-04
Figure 1
Section 7
PUMP DISASSEMBLY

11 WILDEN PUMP & ENGINEERING, LLC
Step 4. Figure 4
Turn pump upside down and loosen bottom retainer.
Step 5. Figure 5
To remove valve seats, use approximately 3/16" rod or
equivalent and push seats out from top to bottom.
Step 6. Figure 6
Inspect ball and seats for abrasion.
Inspect seat o-rings and bottom retainer
o-rings for swelling, cracking, or other
damage. These parts should be replaced
if damage is observed.
Step 7. Figure 7
Loosen clamp band with 5/16" socket
and 3/8" wrench. Remove screw and
nut.
Step 8. Figure 8
Rotate clamp band as shown and
remove by sliding the clamp band up.
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WILDEN PUMP & ENGINEERING, LLC
Step 9. Figure 9
Remove liquid chambers by pulling chamber away from cen-
ter section and inlet-discharge T-sections.
Step 10. Figure 10
Remove T-section from liquid chamber. Remove T-section
o-rings from T-section with an o-ring pick. Care should be
utilized to not damage o-ring. Inspect and replace as neces-
sary.
Step 11. Figure 11
Loosen outer piston, with 7/16" wrench and 7/16" socket
and twist off outer piston. Remove diaphragm and inner
piston.
NOTE: PTFE-fitted pumps employ a PTFE diaphragm with
an integral outer piston. Turn diaphragm counterclockwise
to loosen.
NOTE: PTFE-fitted pumps utilize a neoprene back-up o-ring.
Rubber- or TPE-fitted pumps do not.
Step 12. Figure 12
Pull the remaining diaphragm which is attached to the shaft
through the center section. Hold diaphragm and remove outer
piston with 7/16" wrench for rubber/TPE fitted pumps (not
shown). Inspection of diaphragms, inner pistons, disc spring,
outer pistons and shaft is now possible.
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13 WILDEN PUMP & ENGINEERING, LLC
Step 1. Figure 1
Remove air valve screws from center section with a 5/32"
hex key (Allen wrench).
Step 2. Figure 2
Take care while removing air valve not to damage gasket.
NOTE: Air valve has molded-in alignment pins for proper
positioning during assembly.
Step 3. Figure 3
Remove air valve end cap by simply pulling it away from air
valve body (no tools required). Inspect o-ring and replace as
needed with genuine Wilden parts.
AIR VALVE DISASSEMBLY:
CAUTION: Before any maintenance or repair is attempted,
the compressed air line to the pump should be discon-
nected and all air pressure allowed to bleed from the
pump. Disconnect all intake, discharge, and air lines. Drain
the pump by turning it upside down and allowing any fluid
to flow into a suitable container. Be aware of hazardous
effects of contact with your process fluid.
The Wilden Plastic P.025 utilizes a revolutionary Pro-Flo®air
distribution system. A 3 mm (1/8”) air inlet connects the air sup-
ply to the center section. Proprietary composite seals reduce
the coefficient of friction and allow the P.025 to run lube-free.
Constructed of Acetal or polypropylene, the Pro-Flo®air distri-
bution system is designed to perform in on/off, non-freezing,
non-stalling, tough duty applications.
TOOLS REQUIRED:
5/32” Hex Head Wrench
O-ring Pick
WIL-10090-E-04
AIR VALVE/CLEANING & INSPECTION

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WILDEN PUMP & ENGINEERING, LLC
Step 4. Figure 4
The air valve spool can now be removed. A 4-40 UNC
(Unified National Coarse thread) screw can be screwed into
the threaded hole located in the center of the spool. Grip
the screw with pliers and remove. If a 4-40 UNC screw is
not available, the spool can be tapped out against a wood
block or blown out with compressed air. Upon reassem-
bly, lubricate air valve with NLGI grade 2 white EP bearing
grease or equivalent.
Step 5. Figure 5
Remove the porous polyethylene muffler element by sliding
it toward the end cap opening. The element can be cleaned
by soaking it in a cleaning solution (no solvents). If the muffler
restricts the air exhaust, replace muffler element.
Step 6. Figure 6
Remove pilot spool retaining ring with an o-ring pick.
Step 7. Figure 7
Push pilot spool through center section and remove. Inspect
seals for integrity and spool for damage. Replace pilot spool
assembly if necessary. Upon reassembly of spool, apply a
film of NLGI grade 2 white EP bearing grease or equivalent.
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15 WILDEN PUMP & ENGINEERING, LLC
Upon performing applicable maintenance to the air distribu-
tion system, the pump can now be reassembled. Please refer
to the disassembly instructions for photos and parts place-
ment. To reassemble pump, follow the disassembly instruc-
tions in reverse order. The air distribution system needs to be
assembled first, then the diaphragms, and finally the wetted
parts. Please find applicable torque specifications in this
section.
When o-rings have been replaced, all P.025s require a break-
in period of 2–3 minutes at air pressure above 60 psig.
Rubber/TPE diaphragm configuration Figure 1 PTFE diaphragm configuration Figure 2
There are two types of diaphragm configurations available for
the P.025: 1) Rubber or TPE diaphragm, and 2) PTFE primary
diaphragm with back-up o-ring. Observe the “This Side Out”
marking on the convex side of the diaphragm. Install the disc
spring, inner piston, diaphragm, back-up o-ring (PTFE-fitted
models only). NOTE: PTFE-fitted pumps employ an integral
piston diaphragm. Add a small amount of Loctite 242 to the
bore of the main shaft. Set up time is 20 minutes. Tighten
outer piston to torque value found below.
Lubricate the main shaft assembly with NLGI grade 2 white
EP bearing grease or equivalent and insert through main
shaft bore in center section. Assemble the other side and
torque to proper value as listed below. Please review the
photos above for proper alignment.
Description of Part Maximum Torque
Air Valve 2.3 N•m (20 in-lbs)
Outer Piston, Rubber and TPE Diaphragms 5.6 N•m (50 in-lbs)
Clamp Band 2.3 N•m (20 in-lbs)
Top and Bottom Retainer, Poly 5.1 N•m (45 in-lbs)
Top and Bottom Retainer, PVDF 5.1 N•m (45 in-lbs)
Top and Bottom Retainer 5.1 N•m (45 in-lbs)
TORQUE SPECIFICATIONS FOR MODEL P.025 PUMPS
• Apply a small amount of Loctite 242 to the steel bore of the
shaft from the diaphragm assembly.
WIL-10090-E-04
REASSEMBLY

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WILDEN PUMP & ENGINEERING, LLC WIL-10090-E-04
P.025 PLASTIC RUBBER/TPE-FITTED EXPLODED VIEW
Section 8
EXPLODED VIEW & PARTS LISTING

17 WILDEN PUMP & ENGINEERING, LLC
Item
# Description
Qty. per
Pump
P.025/PPPPP
P/N
P.025/KKPPP
P/N
1 Pro-Flo®Air Valve Assembly11 00-2000-20-700 02-2000-20-700
2 Pro-Flo®Air Valve End Cap 1 00-2300-20-700 00-2300-20-700
3 End Cap O-Ring (–017) 1 00-2390-52-700 00-2390-52-700
4 Muffler Element 1 00-3240-26-700 00-3240-26-700
5 Air Valve Bolt 4 00-6000-03-700 00-6000-03-700
6 Air Valve Gasket 1 00-2600-52-700 00-2600-52-700
7 Air Valve Nut 4 01-6400-03 01-6400-03
8 Pro-Flo®Center Section 1 00-3150-20-700 00-3150-20-700
9 Pilot Spool Assembly 1 00-3850-99-700 00-3850-99-700
10 Pilot Spool Retaining Ring 1 00-2650-03-700 00-2650-03-700
11 Shaft 1 00-3800-99-700 00-3800-99-700
12 Disc Spring 2 00-6800-08 00-6800-08
13 Inner Piston for Rubber/TPE 2 00-3700-20-700 00-3700-20-700
14 Outer Piston 2 00-4570-20 00-4570-21
15 Liquid Chamber 2 00-5001-20 00-5001-21
16 Manifold Tee-Section 2 00-5160-20 00-5160-21
17 Top Retainer 2 00-5411-20 00-5411-21
18 Bottom Retainer 2 00-5420-20 00-5420-21
19 Valve Seat 4 00-1130-20 00-1130-21
20 Valve Seat O-Ring* 4 * *
21 Combo Retainer O-Ring* 4 * *
22 Valve Ball 4 00-1080-55 00-1080-55
23 Tee Section O-Ring* 4 * *
24 Diaphragm* 2 * *
25 Clamp Band Assembly 2 00-7300-03 00-7300-03
26 – Clamp Band Bolt 4 01-6100-03 01-6100-03
27 – Clamp Band Nut 4 01-6400-03 01-6400-03
*Refer to Elastomer Options in Section 10.
1Air Valve Assembly includes items 2, 3, and 4.
All boldface items are primary wear parts.
WIL-10090-E-04
EXPLODED VIEW & PARTS LISTING
P.025 PLASTIC RUBBER/TPE-FITTED PARTS LISTING

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WILDEN PUMP & ENGINEERING, LLC WIL-10090-E-04
EXPLODED VIEW & PARTS LISTING
P.025 PLASTIC PTFE-FITTED EXPLODED VIEW