CAT Pumps 781, 2831K, 2831, 781K Service Manual

8 & 28PFR PLUNGER PUMP SERVICE MANUAL

®

8 FRAME BLOCK-STYLE MANIFOLD: 781, 781K
28 FRAME BLOCK-STYLE MANIFOLD: 2831, 2831K

INSTALLATION AND START-UP INFORMATION

Optimum performance of the pump is dependent upon the entire liquid system and will be obtained only
with the proper selection, installation of plumbing, and operation of the pump and accessories.

SPECIFICATIONS: Maximum specifications refer to individual attributes. It is not
implied that all maximums can be performed simultaneously. If more than one
maximum is considered, check with your CAT PUMPS supplier to confirm the proper
performance and pump selection. Refer to individual pump Data Sheet for complete
specifications, parts list and exploded view.

LUBRICATION: Fill crankcase with special CAT PUMP oil per pump specifications
[8 PFR - 25 oz., 28 PF R - 84 oz. ]. D O NOT RUN PUMP WIT HO UT O IL IN
CRANKCASE. Change initial fill after 50 hours running period. Thereafter, change oil
every 3 months or 500 hour intervals.

PUMP ROTATION: Pump was designed for forward rotation to allow optimum lubri­cation of the crosshead area. Reverse rotation is acceptable if the crankcase oil
level is increased slightly above center dot to assure adequate lubrication.

PULLEY SELECTION: Select size of motor pulley required to deliver the desired flow
from Horsepower Requirement and Pulley Selection Chart (refer to Tech Bulletin
003 or individual Data Sheet).

DRIVE SELECTION: The motor or engine driving the pump must be of adequate
horsepower to maintain full RPM when the pump is under load. Select the electric
mot or from t he Horsepow er Requirem ent C hart acc ording to requir ed pump
discharge flow, maximum pressure at the pump and drive losses of approximately
3-5%. Consult the manufacturer of gas or diesel engine for selection of the proper
engine size.

MOUNTING: Mount the pump on a rigid, horizontal surface in a manner to permit
drainage of crankcase oil. An uneven mounting surface will cause extensive dam­age to the pump base. To minimize piping stress, use appropriate flexible hose to
inlet and discharge ports. Use the correct belt; make sure pulleys are aligned.
Excessive belt tension may be harmful to the bearings. Hand rotate pump before
starting to be certain shaft and bearings are free moving.

LOCATION: If the pump is used in extremely dirty or humid conditions, it is recom­mended pump be enclosed. Do not store or operate in excessively high temperature
areas or enclosed without proper ventilation.

INLET CONDITIONS: Refer to complete Inlet Condition Check-List in this manual
before starting system. DO NOT STARVE THE PUMP OR RUN DRY.Temperatures
above 130°F are permissible. Add 1/2 PSI inlet pressure per each degree F over
130°F. Elastomer or RPM changes may be required. See Tech Bulletin 002 or call
CAT PUMPS for recommendations.

C.A.T.: Installation of a C.A.T. (Captive Acceleration Tube) is recommended in ap­plications with stressful inlet conditions such as high temperatures, booster pump
feed, long inlet lines or quick closing valves.

DISCHARGE PLUMBING: OPEN ALL VALVES BEFORE STARTING SYSTEM to
avoid deadhead overpressure condition and severe damage to the pump or system.

Install a Pulsation Dampening device
as close to the head as possible. Be certain the pulsation dampener (Prrrrr-o-lator) is
properly precharged for the system pressure (refer to individual Data Sheet).

on the discharge head or in the discharge line

A reliable Pressure Gauge should be installed near the discharge outlet of the high
pressure manifold. This is extremely important for adjusting pressure regulating
devices and also for proper sizing of the nozzle or restricting orifice. The pump is
ra te d f or a maxi mu m pre ssure; thi s is t he pre ss ure t ha t is read at th e
discharge manifold of the pump, NOT AT THE GUN OR NOZZLE.

Use PTFE thread tape or pipe thread sealant (sparingly) to connect accessories or
plumbing. Exercise caution not to wrap tape beyond the last thread to avoid tape
from becoming lodged in the pump or accessories. This condition will cause a mal­function of the pump or system.

PRESSURE REGULATION: All systems require both a primary pressure regulating
device (i.e., regulator, unloader) and a secondary pressure safety relief device (i.e.,
pop-off valve, safety valve). The primary pressure device must be installed on the
discharge side of the pump. The function of the primary pressure regulating device
is to protect the pump from over pressurization, which can be caused by a plugged
or closed off discharge line. Over pressurization can severely damage the pump,
other system components and can cause bodily harm. The secondary safety relief
device must
the opposite side of the manifold head.This will ensure pressure relief of the sys­tem if the primary regulating device fails. Failure to install such a safely device will
void the warranty on the pump.

If a large portion of the pumped liquid is by-passed (not used) when the high pressure
system is running, this by-pass liquid should be routed to an adequately sized, baffled
supply tank or to drain. If routed to the pump inlet, the by-pass liquid can quickly
develop excessive heat and result in damage to the pump. A temperature
control device to shut the system down within the pump limits or multiple THERMO
VALVES must be installed in the by-pass line to protect the pump.

NOZZLES: A worn nozzle will result in loss of pressure. Do not adjust pressure
regulating device to compensate. Replace nozzle and reset regulating device to
system pressure.

PUMPED LIQUIDS: Some liquids may require a flush between operations or
before storing. For pumping liquids other than water, contact your CAT PUMPS

supplier.
SPECIAL “K” MODELS: Standard pumps have internal weep holes between the

V-Packings and Lo-Pressure Seals allowing the pumped liquid to cool the back side
of the packings. The “K” models do not have the internal weep holes and do no
connect to the inlet side. They have special ports on both sides of the inlet manifold
that can be fitted to an external flushing system to provide cooling and flushing.

STORING: For extended storing or between use in cold climates, drain all pumped
liquids from pump and flush with antifreeze solution to prevent freezing and
damage to the pump. DO NOT RUN PUMP WITH FROZEN LIQUID (refer to Tech
Bulletin 083).

be installed in-line between the primary device and the pump or on

t

All systems require both a primary pressure regulating device (i.e., regulator, unloader) and a secondary pressure safety relief device (i.e., pop-off valve, safety valve).
Failure to install such relief devices could result in personal injury or damage to the pump or to system components. CAT PUMPS does not assume any liability or responsibility
for the operation of a customer’s high pressure system.

World Headquarters

1681 - 94th Lane N.E. Minneapolis, MN 55449- 4324

Phone [phone] — FAX [phone]

e-mail: [e-mail]

CAT PUMPS

www.catpumps.com

®

The Pumps with Nine Lives

International Inquiries

FAX [phone]

e-mail: [e-mail]

WARNING

CAT PUMPS (U.K.) LTD.

1 Fleet Business Park, Sandy Lane, Church Crookham

FLEET, Hampshire, GU52 8BF, England

Phone Fleet 44 1252-622031 — Fax [phone]

N.V. CAT PUMPS INTERNATIONAL S. A.

CAT PUMPS DEUTSCHLAND GmbH

e-mail: [e-mail]

Heiveldekens 6A, B-2550 Kontich, Belgium

Phone [phone] — Fax [phone]

e-mail: [e-mail] www.catpumps.be

Buchwiese 2, D-65510 Idstein, Germany

Phone [phone] — Fax [phone]

e-mail: [e-mail] www.catpumps.de

PN 31997 Rev D 3833

781

Removal of Valve Block Manifold

CAUTION: Before commencing with service, shut off drive (electric motor, gas or diesel engine) and turn off water supply to pump. Relieve all dis­charge line pressure by triggering gun or opening valve in discharge line.

After servicing is completed, turn on water supply to pump, start drive, reset pressure regulating device and secondary valve, read system pressure on the
gauge at the pump head. Check for any leaks, vibration or pressure fluctuations and resume operation.

Inspect and service all system accessories on the same schedule as your pump.

781

Removal of Valve Assembly from
Inlet/Discharge Manifold

781

Complete Inlet/Discharge Valve
Assembly

781

Removal of VP Cylinder from
Inlet/Discharge Manifold

SERVICING THE VALVES - 781/781K and 2831/2831K

(Discharge and Inlet Valves)

Disassembly

NOTE: Both the standard and the “K” versions are serviced
in the same manner.

1. To service the Discharge or Inlet Valve Assemblies, it is nec­essary to remove the Valve Block Manifold (VBM).

2. Using an allen wrench, remove the Hex Socket Head screws
(HSH) from the VBM.

3. On the model 781, insert two M8 x 114 metric threaded bolts
into the upper left and lower right intermediate holes on the
VBM face. Thread in bolts until they make contact with Inlet
Manifold/Discharge Manifold (IMDM) drilled holes. Continue
threading until manifolds begin to separate. Support under­side of VBM to avoid possible damage to ceramic plungers or
plunger rods

NOTE: The Valve Assemblies may stay with either the
VBM or the IMDM.

4. If the Inlet Valve Assemblies (lower chamber) stay in the
IMDM or the Discharge Valve Assemblies (upper chamber)
stay in the VBM, then grasp Spring Retainer tabs and pull
assemblies from valve chambers.

NOTE: The model 2831 has Valve Adapters with O-Rings
and Back-up-Rings that may remain with Inlet or
Discharge Valve Assemblies when removed.

5. If the Inlet Valve Assemblies (lower chamber) stay in the
VBM or the Discharge Valve Assemblies (upper chamber)
stay in the IMDM, then remove exposed O-Rings (781).
Insert two screwdrivers into the groove on opposite sides of
the Seat (781) or secondary groove on the Valve Adapter
(2831) and pry from valve chamber.

CAUTION: Exercise caution as the screwdrivers may
score o-ring sealing area.

6. To separate Valve Assemblies, insert screwdriver into
Spring Retainer and press the backside of Valve until Seat
separates from the Spring Retainer. Each assembly consists
of a Retainer Washer, Spring Retainer, Spring, Valve, Seat,
O-Ring and Back-up-Ring.

7. On the model 2831, remove Seat from the Valve Adapter by
inserting reverse pliers through Seat opening and gently pull
out.

CAUTION: Exercise caution as the reverse pliers may
score sealing areas.

2831

Removal of Valve Adapter from Inlet/Discharge
Manifold

2831

Complete Inlet/Discharge Valve Assembly

2831

Removal of HPS Spacer from Inlet/Discharge Manifold

781

V-Packing arrangement.

781

Lo-Pressure Seal and Adapter

781

Plunger arrangement

Reassembly

NOTE: For certain applications apply liquid gasket to the
O-Ring crevices and seal surfaces. Refer to Tech Bulletin
053 for model identification.

1. Examine Retainer Washers for fatigue or wear and replace
as needed.

2. Examine Spring Retainers for internal wear or breaks in the
structure and replace as needed.

3. Examine Springs for fatigue or breaks and replace as needed.

4. Examine Valves and Seats for grooves, pitting or wear and
replace as needed.

5. Examine Seat O-Rings and Back-up-Rings for cuts or wear
and replace as needed.

6. On the model 2831, examine Valve Adapter for external sur­face scoring or wear and replace as needed. Examine Valve
Adapter O-Rings for cuts or wear and replace as needed.
Install Back-up-Ring, then O-Ring into large groove.

NOTE: A new Valve Assembly will come pre-assembled
in the Valve kit. Continue with steps 11 through 13. If servic­ing from individual parts, follow steps 7 through 13.

7. Place VBM on work surface with IMDM side up.

8. On the model 781, install Back-up-Rings and O-Rings onto
both the front and rear of the seat with the O-Rings to the
outside. On the model 2831, install Back-up-Ring and
O-Ring on the Seat with the O-Rings facing to the inside.

9. On the model 781, place Seat with O-Rings and Back-up­Rings on work surface with dish side up. Then place the
Valve onto the Seat with dish side down/Spring tab up. On
the model 2831, place Valve Adapter on work surface with
Back-up-Ring and O-Ring facing up. Press O-Ring side of
Seat into Valve Adapter. Then place valve onto seat with dish
side down.

10. Place Spring on Valve and snap Spring Retainer onto Seat.

11. On the model 781, insert Retainer Washer into valve chamber
with curved side down. On the model 2831, place flat
Retainer Washer into valve chamber. Press Valve Assembly
into the valve chamber until completely seated.

12. On the model 2831, insert O-Rings into groove at bottom of
Valve Adapters.

13. Support the VBM from the under side and align manifold with
IMDM. Apply anti-seize to HSH screw threads and thread in
hand tight. Torque in sequence to specifications in torque chart.

2831

Hi-Pressure Seal arrangement.

2831

Lo-Pressure Seal

2831

Plunger arrangement

SERVICING THE SEALS - 781/781K and 2831/2831K

Disassembly

NOTE: Both the standard and the “K” versions are serviced
in the same manner. All parts necessary for servicing are
included in the Seat Kit.

CAUTION: Exercise caution as the reverse pliers may
score sealing areas.

1. To service the seals, it is necessary to remove both the VBM
and IMDM. Follow the disassembly procedure found under

SERVICING THE VALVES.
NOTE: The V-Packing Cylinder (781) or Hi-Pressure Seal

Spacers (HPS) (2831) may stay in the VBM or IMDM.

2. Remove the exposed O-Rings and insert two screwdrivers
into the grooves on opposite sides of the V-Packing Cylinder
(781) or into the secondary groove on the HPS Spacer
(2831) and pry from the chamber.

CAUTION: Exercise caution as the screwdriver may
score o-ring sealing area.

3. On the model 781, remove Female Adapters from each
chamber.

4. On the model 781, use reverse pliers to remove three
V-Packings and one Male Adapter from each V-Packing
Cylinder.

5. On the model 2831, use reverse pliers to remove one
Hi-Pressure Seal from each IMDM chamber.

6. Invert IMDM and place on flat work surface with crankcase

side up.

7. On the model 781, use reverse pliers to remove three Inlet
Adapter Assemblies by grasping the Inlet Adapter.

8. Use reverse pliers to remove Lo-Pressure Seals from back­side of Inlet Adapter (781) or the IMDM chamber (2831).

Reassembly

NOTE: For certain applications apply liquid gasket to the
O-Ring crevices and seal surfaces. Refer to Tech Bulletin
053 for model identification.

NOTE: For standard installation, apply a small amount of
oil to the outside edge of the LPS, HPS, VP, MA, FA for
ease of installation and to avoid damage.

Models 781 and 781K

1. Examine Lo-Pressure Seals for wear to the internal ridges,
outer surfaces or for broken springs and replace as needed.

2. Examine Inlet Adapters for scale build up or wear, and the
Inlet Adapter O-Rings for cuts or deterioration and replace as
needed.

NOTE: When using alternate materials, the fit of the spe­cial materials may be snug and require gently driving the
LPS into position with a cylinder of the same diameter to
assure a square seating and no damage to the LPS.

3. Press new Lo-Pressure Seals into the Inlet Adapters with the

garter spring up.

4. Press Inlet Adapter Assembly into each chamber of the
IMDM with the garter spring down.

5. Invert IMDM and place on flat work surface with crankcase

side down.

6. Examine the V-Packing Cylinder for scale build-up, wear and
replace as needed. Examine V-Packing Cylinder O-Rings
and Back-up-Rings for cuts or deterioration and replace as
needed.

7. Examine Male and Female Adapters for wear and replace as
needed.

8. Examine V-Packings for frayed edges or wear and replace as
needed.

9. Place the Male Adapters into the V-Packing Cylinder with flat

side down.

10. Insert three new V-Packings into each V-Packing Cylinder
with “V” groove down. The “V” will mate with “V side” of the
Male Adapter.

11. Position Female Adapter into the IMDM with “V” groove up.

12. Press V-Packing Cylinder Assembly into IMDM center chambers
with V-Packings facing into the manifold chamber.

13. Support the IMDM from the under side and align the manifold
bolt holes with crankcase holes. Apply Loctite

®

242®to HSH
screw threads and thread in hand tight. Torque in sequence
to specifications in torque chart.

14. Support the VBM from the under side and align manifold with
IMDM. Apply anti-seize to HSH screw threads and thread in
hand tight. Torque in sequence to specifications in torque
chart.

13 5 7 11

TORQUE SEQUENCE

13

910

42

12 8 6 14

Models 2831 and 2831K

1. Examine Lo-Pressure Seals for wear to the internal ridges,
outer surfaces or for broken springs and replace as needed.

2. Press new Lo-Pressure Seals into IMDM with the garter

spring down.
NOTE: When using alternate materials, the fit of the spe-

cial materials may be snug and require gently driving the
LPS into position with a cylinder of the same diameter to
assure a square seating and no damage to the LPS.

3. Invert IMDM and place on flat work surface with crankcase
side down.

4. Examine HPS Spacer for scale build-up, wear and replace as
needed. Examine HPS Spacer O-Rings for cuts or deteriora­tion and replace as needed.

5. Examine Hi-Pressure Seals for frayed edges or wear and
replace as needed.

6. Press Hi-Pressure Seal into each IMDM center chamber with
metal backing facing down into the manifold chamber.

7. Press HPS Spacer into each center manifold chamber with

secondary groove facing out.

8. Support the IMDM from the under side and align the manifold
bolt holes with crankcase holes. Apply Loctite

®

242®to HSH
screw threads and thread in hand tight. Torque in sequence
to specifications in torque chart.

9. Support the VBM from the under side and align manifold with
IMDM. Apply anti-seize to HSH screw threads and thread in
hand tight. Torque in sequence to specifications in torque
chart.

13 5 7 15

TORQUE SEQUENCE

91311
12 4 2 10
16 8 6 14

SERVICING THE PLUNGERS - 781/781K and 2831/2831K

Disassembly

NOTE: Both the standard and the “K” versions are serviced
in the same manner.

1. To service the plungers, it is necessary to remove both the
VBM and IMDM. Follow the disassembly procedure found
under SERVICING THE VALVES.

2. Remove the one piece Seal Retainer from each Plunger Rod.

3. Using a Hex tool, loosen the Plunger Retainers about three to
four turns.

4. Push the Ceramic Plungers back towards the crankcase to
separate from the Plunger Retainers and proceed with un­threading the Plunger Retainers by hand.

5. Remove Plunger Retainers, O-Rings, Back-up-Rings and
Gaskets.

NOTE: Plunger Retainer Studs may stay on Plunger
Rods or come off with Plunger Retainers.

6. Remove Ceramic Plungers, Keyhole Washers and Barrier
Slingers.

Reassembly

1. Visually inspect Crankcase Oil Seals for deterioration or leaks
and contact CAT PUMPS for assistance with replacement.
See SERVICING THE CRANKCASE section.

2. Examine Plunger Retainers, Studs, Barrier Slingers and
Keyhole Washers for wear and replace as needed.

3. Slide Barrier Slingers over Plunger Retainer Studs with con-

cave side away from crankcase.

4. Slide Keyhole Washers over Plunger Retainer Studs with

split ends facing downward.

5. Examine Ceramic Plungers for scoring, scale build-up, chips
or cracks and replace as needed.

6. Slide Ceramic Plungers over Plunger Retainer Studs.

NOTE: Plunger can only be installed in one direction. Do
not force onto Plunger Rod.

7. Examine Gaskets, O-Rings and Back-up-Rings for cuts or
wear and replace as needed.

8. Install Gaskets first, then O-Rings and Back-up-Rings onto
Plunger Retainers.

NOTE: Lubricate O-Rings and Back-up-Rings for ease in
installation and to reduce possible damage.

9. Apply Loctite
Retainer Studs. Thread on Plunger Retainer and torque per
chart.

10. On the model 781, install Seal Retainers with drain slots facing
the crankcase with openings to the top and bottom. On the
model 2831 the drain openings must face the manifold.

11. Support the IMDM from the under side and align manifold
bolt holes with crankcase holes. Apply Loctite
screws threads and thread in hand tight. Torque in sequence
to specifications in torque chart.

12. Support the VBM from the under side and align manifold with
IMDM. Apply anti-seize to HSH screw threads and thread in
hand tight. Torque in sequence to specifications in torque
chart.

®

242®to exposed threaded end of Plunger

®

242®to HSH

SERVICING THE CRANKCASE SECTION - 781/781K
and 2831/2831K

NOTE: Both the standard and the “K” versions are serviced
in the same manner.

1. While manifolds, plungers and seal retainers are removed ex­amine crankcase oil seals for leaking and wear.

2. Check for any signs of leaking at Rear Cover, Drain Plug,
and Bubble Oil Gauge (781) or Rear Cover, Drain Plug, and
Dipstick (2831).

3. Check oil level and for evidence of water in oil. Change
crankcase oil on a regular schedule. See Preventative
Maintenance Check-List.

4. Rotate crankshaft by hand to feel for smooth bearing movement.

5. Examine crankshaft oil seals externally for drying, cracking or
leaking.

6. Contact CAT PUMPS or your local distributor if crankcase
service is required. Refer to Tech Bulletin 035.

Loctite and 242 are registered trademarks of the Henkel Corporation.

PREVENTATIVE MAINTENANCE CHECK-LIST

Check Daily Weekly 50 hrs. 500 hrs.* 1500 hrs.** 3000 hrs.**

Clean Filters x
Oil Level/Quality x
Oil Leaks x
Water Leaks x
Belts, Pulley x
Plumbing x
Initial Oil Change x
Oil Change x
Seal Change x
Valve Change x
Accessories x

* If other than CAT PUMPS special multi-viscosity ISO68 oil is used,

change cycle should be every 300 hours.

** Each system’s maintenance cycle will be exclusive. If system per-

formance decreases, check immediately. If no wear at 1500 hours,
check again at 2000 hours and each 500 hours until wear is ob­served. Valves typically require changing every other seal change.

Duty cycle, temperature, quality of pumped liquid and inlet feed
conditions all effect the life of pump wear parts and service cycle.

** Remember to service the regulator/unloader at each seal servicing

and check all system accessories and connections before resuming
operation.

TORQUE CHART

Pump Item Torque
Pump Model Thread Tool Size [P/N] in.lbs. ft.lbs. Nm

Plunger Retainer

781 M5 M11 Hex 55 4.4 6
2831 M7 M14 Hex 90 7.2 10

Inlet/Discharge Manifold Screws

781 M10 M8 Allen [33046] 250 20.8 28
2831 M12 M10 Allen [33047] 355 29.6 40

Valve Block Manifold Screws

781 M10 M8 Allen [33046] 250 20.8 28
2831 M12 M10 Allen [33047] 355 29.6 40

Crankcase Cover/Bearing Cover Screws

781 M6 M10 Hex [25082] 115 9.4 13
2831 M8 M13 Hex [25324] 115 9.4 13

Connecting Rod Screws

781, 2831 M8 M13 Hex [25324] 130 10.8 15

Bubble Oil Gauge

781, 2831 M28 Oil Gauge Tool [44050] 45 3.6 5

TECHNICAL BULLETIN REFERENCE CHART

No. Subject Models
002 Inlet Pressure VS Liquid Temperature All Models
003 Power Unit Drive Packages 3PFR - 68PFR, 10FR - 60FR
024 Lubrication of Lo-Pressure Seals All Models
035 Servicing Crankcase Section 7PFR - 60PFR
036 Cylinder and Plunger Reference Chart All Models
043 LPS and HPS Servicing All Plunger Models
053 Liquid Gasket All Plunger NAB-S.S. Models
064 By-Pass Hose Sizing All Unloaders/Regulators
074 Torque Chart Piston and Plunger Pumps
077 Oil Drain Kit All Models (except 2SF/4SF)
083 Winterizing a Pump All Models
085 M8 Keyway 25FR, 25PFR, 28PFR

INLET CONDITION CHECK-LIST

Review Before Start-Up

Inadequate inlet conditions can cause serious malfunctions in the best designed
pump. Surprisingly, the simplest of things can cause the most severe problems or go
unnoticed to the unfamiliar or untrained eye. REVIEW THIS CHECK-LIST BEFORE
OPERATION OF ANY SYSTEM. Remember, no two systems are alike, so there can
be no ONE best way to set-up a system. All factors must be carefully considered.

INLET SUPPLY should exceed the maximum flow being delivered by the pump to
assure proper performance.
❏ Open inlet shut-off valve and turn on water supply to avoid starving pump.

DO NOT RUN PUMP DRY.

❏ Temperatures above 130°F are permissible. Add 1/2 PSI inlet pressure per each

degree F over 130°F. Elastomer or RPM changes may be required. See Tech
Bulletin 002 or call CAT PUMPS for recommendations.

❏ Avoid closed loop systems especially with high temperature, ultra-high pressure

or large volumes. Conditions vary with regulating/unloader valve.

❏ Low vapor pressure liquids, such as solvents, require a booster pump and C.A.T.

to maintain adequate inlet supply.

❏ Higher viscosity liquids require a positive head and a C. A.T. to assure adequate

inlet supply.

❏ Higher temperature liquids tend to vaporize and require positive heads and

C.A.T. to assure adequate inlet supply.

❏ When using an inlet supply reservoir, size it to provide adequate liquid to accom-

modate the maximum output of the pump, generally a minimum of 6-10 times the
GPM (however, a combination of system factors can change this requirement);
provide adequate baffling in the tank to eliminate air bubbles and turbulence;
install diffusers on all return lines to the tank.

INLET LINE SIZE should be adequate to avoid starving the pump.
❏ Line size must be a minimum of one size larger than the pump inlet fitting. Avoid

tees, 90 degree elbows or valves in the inlet line of the pump to reduce the risk of
flow restriction and cavitation.

❏ The line MUST be a FLEXIBLE hose, NOT a rigid pipe, and reinforced on SUCTION

systems to avoid collapsing.

❏ The simpler the inlet plumbing the less the potential for problems. Keep the

length to a minimum, the number of elbows and joints to a minimum (ideally no
elbows) and the inlet accessories to a minimum.

❏ Use pipe sealant to assure air-tight, positive sealing pipe joints.
INLET PRESSURE should fall within the specifications of the pump.

❏ Acceleration loss of liquids may be increased by high RPM, high temperatures,

low vapor pressures or high viscosity and may require pressurized inlet and
C.A.T.to maintain adequate inlet supply. DO NOT USE C.A.T. WITH SUCTION
INLET.

❏ Optimum pump performance is obtained with +20 PSI (1.4 BAR) inlet pressure

and a C.A.T.for certain applications. With adequate inlet plumbing, most pumps
will perform with flooded suction. Maximum inlet pressure is 70 PSI (4.9 BAR).

❏ After prolonged storage, pump should be rotated by hand and purged of air to

facilitate priming. Disconnect the discharge port and allow liquid to pass through
pump and measure flow.

❏ “K” versions are suitable for high inlet pressures. Consult CAT PUMPS.
INLET ACCESSORIES are designed to protect against over pressurization, control

inlet flow, contamination or temperature and provide ease of servicing.

❏ A shut-off valve is recommended to facilitate maintenance.
❏ Installation of a C. A.T. is essential in applications with stressful conditions such

as high temperatures, booster pump feed or long inlet lines. Do not use C.A.T.
with negative inlet pressure.

❏ A stand pipe can be used in some applications to help maintain a positive head

at the pump inlet line.

❏ Inspect and clean inlet filters on a regular schedule to avoid flow restriction.
❏ A pressure transducer is necessary to accurately read inlet pressure. Short

term, intermittent cavitation will not register on a standard gauge.

❏ All accessories should be sized to avoid restricting the inlet flow.
❏ All accessories should be compatible with the solution being pumped to prevent

premature failure or malfunction.

❏ Optional inlet protection can be achieved by installing a pressure cut off switch

between the inlet filter and the pump to shut off pump when there is no positive
inlet pressure.

❏ “K” versions are suitable for high temperatures and containment of harmful

liquids. Consult CAT PUMPS for optional flushing and cooling accessory.

BY-PASS TO INLET Care should be exercised when deciding the method of by-pass
from control valves.
❏ It is recommended the by-pass be directed to a baffled reservoir tank, with at

least one baffle between the by-pass line and the inlet line to the pump.

❏ Although not recommended, by-pass liquid may be returned to the inlet line of the

pump if the system is properly designed to protect your pump. When a pulsation
dampener is used, a PRESSURE REDUCING VALVE must be installed on the
inlet line (BETWEEN THE BY-PASS CONNECTION AND THE INLET TO THE
PUMP) to avoid excessive pressure to the inlet of the pump. It is also recommend­ed that a THERMO VALVE be used in the by-pass line to monitor the temperature
build-up in the by-pass loop to avoid premature seal failure.

❏ A reinforced, flexible, low pressure hose rated up to 300 PSI should be used for

routing by-pass back to the pump inlet.

❏ Caution should be exercised not to undersize the by-pass hose diameter and

length. Refer to Technical Bulletin 064 for additional information on the size and
length of the by-pass line.

❏ Check the pressure in the by-pass line to avoid over pressurizing the inlet.
❏ The by-pass line should be connected to the pump inlet line at a gentle angle of

45° or less and no closer than 10 times the pump inlet port diameter e.g. 1-1/2"
port size = 15" distance from pump inlet port.

HOSE FRICTION LOSS

PRESSURE DROP IN PSI PER 100 FT OF HOSE

Water*

Flow

Gal/Min

0.5 16 5 2
1 54 20 7 2
2 180 60 25 6 2
3 380 120 50 13 4 2
4 220 90 24 7 3
5 320 130 34 10 4
6 220 52 16 7 1
8 300 80 25 10 2
10 450 120 38 14 3
15 900 250 80 30 7
20 1600 400 121 50 12
25 650 200 76 19
30 250 96 24
40 410 162 42
50 600 235 62
60 370 93

*At a fixed flow rate with a given size hose, the pressure drop across a given hose length
will be directly proportional. A 50 ft. hose will exhibit one-half the pressure drop of a 100
ft. hose. Above values shown are valid at all pressure levels.

1/4 5/16 3/8 1/2 5/8 3/4 1"

WITH TYPICAL WATER FLOW RATES

Hose Inside Diameters, Inches

WATER LINE PRESSURE LOSS

PRESSURE DROP IN PSI PER 100 FEET

Steel Pipe—Nominal Dia.

Water

GPM

1/4 3/8 1/2 3/4 1 11/4 11/2

8.5 1.9

1

30 7.0 2.1

2

60 14 4.5 1.1

3

150 36 12 2.8

5

330 86 28 6.7 1.9

8

520 130 43 10 3.0

10

270 90 21 6.2 1.6

15

670 240 56 16 4.2 2.0

25
40

60
80

100

66 17 8.0

210 107 48

Brass Pipe—Nominal Dia.

1/4 3/8 1/2 3/4 1

6.0 1.6
20 5.6 1.8
40 11 3.6

100 28 9.0 2.2
220 62 21 5.2 1.6
320 90 30 7.8 2.4

37 17
52 29

11/4 11/2

190 62 16 5.0 1.5
470 150 40 12 3.8 1.7

39 11 5.0

23 11
40 19
61 28

Copper Tubing O.D. Type L

1/4 3/8 1/2 5/8 3/4 7/8

120 13 2.9 1.0
400 45 10 3.4 1.3

94 20 6.7 2.6

230 50 17 6.1 3.0
500 120 40 15 6.5

180 56 22 10

120 44 20
330 110 50
550 200 88

Handy Formulas to Help You

Q. How can I find the RPM needed to get specific GPM

(Gallons Per Minute) I want?

A. Desired RPM = Desired GPM x

Rated RPM
Rated GPM

Q. I have to run my pump at a certain RPM. How do I figure

the GPM I’ll get?

A. Desired GPM = Desired RPM x

Rated GPM
Rated RPM

Q. Is there a simple way to find the approximate horsepower

I’ll need to run the pump?

A. Electric Brake GPM x PSI (Standard 85%

Horsepower Required

=

1460 Mech. Efficiency)

Q. What size motor pulley should I use?
A. Pump Pulley (Outer Diameter) x

Pump RPM

Motor/Engine RPM

(Consult

Engine Mfr.)

Q. How do I calculate the torque for my hydraulic drive

system?

A. Torque (ft. lbs.) = 3.6

GPM x PSI

( )

RPM

Avoid Cavitation Damage

RESISTANCE OF VALVES AND FITTINGS

Nominal

Pipe

Inside

Size

Diameter

Inches

Inches

1/2 0.622 0.41 18.5 9.3 0.78 1.67 3.71 0.93 3.33
3/4 0.824 0.54 24.5 12.3 1.03 2.21 4.90 1.23 4.41

1 1.049 0.69 31.2 15.6 1.31 2.81 6.25 1.56 5.62

1

1

/4 1.380 0.90 41.0 20.5 1.73 3.70 8.22 2.06 7.40

1

1

/2 1.610 1.05 48.0 24.0 2.15 4.31 9.59 2.40 8.63

2 2.067 1.35 61.5 30.8 2.59 5.55 12.30 3.08 11.60

1

2

/2 2.469 1.62 73.5 36.8 3.09 6.61 14.70 3.68 13.20
3 3.068 2.01 91.5 45.8 3.84 8.23 18.20 4.57 16.40
4 4.026 2.64 120.0 60.0 5.03 10.80 23.90 6.00 21.60

Arriving at a total line pressure loss, consideration should then be given to
pressure loss created by valves, fittings and elevation of lines.

If a sufficient number of valves and fittings are incorporated in the system to
materially affect the total line loss, add to the total line length, the equivalent
length of line of each valve or fitting.

Equivalent Length of Standard Pipe in Feet

Gate

Globe

Angle

Valve

Valve

Valve

45˚

Elbow

90˚

Elbow

180˚

Close

Ret

Tee

Thru

Run

Tee

Thru

Branch

TYPICAL RESERVOIR TANK

RECOMMENDED 6 TO 10 TIMES SYSTEM CAPACITY

Supply Line

→

T

D

X

→

1.5 x D (Min.)

→

(Dia of pipe)

→

Level Sensing

Device

→

Bypass Line

(from regulator or unloader)

→

MIN. 4"

→

Flexible Hose
to Pump

FILTER

→

MIN. 4"

→

Minimum

Liquid

Level

Bypass Line

(from regulator or

unloader)

Minimum Two Baffles

Sealed at Bottom

One or several of the conditions shown in the chart below may
contribute to cavitation in a system resulting in premature wear,
system downtime and unnecessary operating costs.

CONDITION SOLUTION

Inadequate inlet
line size larger

Water hammering
liquid acceleration/
deacceleration

Rigid Inlet Plumbing●Use flexible wire reinforced hose to absorb

Excessive Elbows in●Keep elbows to a minimum and less than 90°
Inlet Plumbing

Excessive Liquid
Temperature

Air Leaks in Plumbing●Check all connections

Agitation in Supply
Tank Minimum 6-10 times system GPM

High Viscosity Liquids●Verify viscosity against pump specifications

Clogged Filters

●

Increase line size to the inlet port or one size

●

Install C.A.T. Tube

●

Move pump closer to liquid supply

pulsation and pressure spikes

●

Use Thermo Valve in bypass line

●

Do not exceed pump temperature specifications

●

Substitute closed loop with baffled holding tank

●

Adequately size tank for frequent or high
volume bypass

●

Pressure feed high temperature liquids

●

Properly ventilate cabinets and rooms

●

Use PTFE thread tape or pipe thread sealant

●

Size tank according to pump output —

●

Baffle tank to purge air from liquid and
separate inlet from discharge

before operation

●

Elevate liquid temperature enough to reduce
viscosity

●

Lower RPM of pump

●

Pressure feed pump

●

Increase inlet line size

●

Perform regular maintenance or use clean
filters to monitor build up

●

Use adequate mesh size for liquid and pump
specifications

DIAGNOSIS AND MAINTENANCE

One of the most important steps in a high pressure system is to establish a regular maintenance program. This will vary slightly with each
system and is determined by various elements such as the duty cycle, the liquid being pumped, the actual specifications vs rated specifications
of the pump, the ambient conditions, the inlet conditions and the accessories in the system. A careful review of the necessary inlet conditions
and protection devices required before the system is installed will eliminate many potential problems.

CAT PUMPS are very easy pumps to service and require far less frequent service than most pumps. Typically, only common tools are required,
making in-field service convenient, however, there are a few custom tools, special to certain models, that do simplify the process. This service
manual is designed to assist you with the disassembly and reassembly of your pump. The following guide will assist in determining the cause
and remedy to various operating conditions. You can also review our FAQ or SERVICE sections on our WEB SITE for more facts or contact
CAT PUMPS directly.

PROBLEM PROBABLE CAUSE SOLUTION

Low pressure •Worn nozzle. •Replace with properly sized nozzle.

•Belt slippage. •Tighten belt(s) or install new belt(s).

•Air leak in inlet plumbing. •Tighten fittings and hoses. Use PTFE liquid or tape.

•Pressure gauge inoperative or not registering accurately. •Check with new gauge. Replace worn or damaged gauge.

•Relief valve stuck, partially plugged or improperly adjusted. •Clean/adjust relief valve. Replace worn seats/valves and o-rings.

•Inlet suction strainer (filter) clogged or improperly sized. •Clean filter. Use adequate size filter. Check more frequently.

•Abrasives in pumped liquid. •Install proper filter.

•Leaky discharge hose. •Replace discharge hose with proper rating for system.

•Inadequate liquid supply. •Pressurize inlet and install C.A.T.

•Severe cavitation. •Check inlet conditions.

•Worn seals. •Install new seal kit. Increase frequency of service.

•Worn or dirty inlet/discharge valves. •Clean inlet/discharge valves or install new valve kit.

Pulsation •Faulty Pulsation Dampener. •Check precharge. If low, recharge, or install a new dampener.

•Foreign material trapped in inlet/discharge valves. •Clean inlet/discharge valves or install new valve kit.

Water leak

•Under the manifold •Worn V-Packings, Hi-Pressure or Lo-Pressure Seals. •Install new seal kit. Increase frequency of service.

•Worn adapter/V/P cylinder o-rings. •Install new o-rings.

•Into the crankcase •Humid air condensing into water inside the crankcase. •Install oil cap protector. Change oil every 3 months or 500 hours.

•Excessive wear to seals and V-Packings. •Install new seal kit. Increase frequency of service.

Knocking noise

•Inlet supply •Inadequate inlet liquid supply. •Check liquid supply. Increase line size, pressurize or install C.A.T.

•Bearing •Broken or worn bearing. •Replace bearing.

•Pulley •Loose pulley on crankshaft •Check key and tighten set screw.

Oil leak

•Crankcase oil seals. •Worn crankcase oil seals. •Replace crankcase oil seals.

•Crankshaft oil seals and o-rings. •Worn crankshaft oil seals or o-rings on bearing cover. •Remove bearing cover and replace o-rings and/or oil seals.

•Drain plug •Loose drain plug or worn drain plug o-ring. •Tighten drain plug or replace o-ring.

•Bubble gauge •Loose bubble gauge or worn bubble gauge gasket. •Tighten bubble gauge or replace gasket.

•Rear cover •Loose rear cover or worn rear cover o-ring. •Tighten rear cover or replace o-ring.

•Filler cap •Loose filler cap or excessive oil in crankcase. •Tighten filler cap. Fill crankcase to specified capacity.

Pump runs extremely rough

•Inlet conditions •Restricted inlet or air entering the inlet plumbing •Correct inlet size plumbing. Check for air tight seal.

•Pump valves •Stuck inlet/discharge valves. •Clean out foreign material or install new valve kit.

•Pump seals •Leaking V-Packings, Hi-Pressure or Lo-Pressure seals. •Install new seal kit. Increase frequency of service.

Premature seal failure •Scored plungers. •Replace plungers.

•Over pressure to inlet manifold. •Reduce inlet pressure per specifications.

•Abrasive material in the liquid being pumped. •Install proper filtration at pump inlet and clean regularly.

•Excessive pressure and/or temperature of pumped liquid. •Check pressure and inlet liquid temperature.

•Running pump dry. •DO NOT RUN PUMP WITHOUT LIQUID.

•Starving pump of adequate liquid. •Increase hose one size larger than inlet port size. Pressurize and
install C.A.T.

•Eroded manifold. •Replace manifold. Check liquid compatibility.