CAT Pumps 7590 User manual

Pressure Sensitive
Multiple Gun
Regulating Unloaders
Models 7590
7592
SPECIFICATIONS
MODEL 7590 U.S. Measure Metric Measure
Flow Range .................................................. 10-52 gpm (38-200 lpm)
Pressure Range ........................................400-2175 psi (30-150 bar)
MODEL 7592
Flow Range .................................................. 10-52 gpm (38-200 lpm)
Pressure Range ........................................450-2500 psi (31-175 bar)
COMMON SPECIFICATIONS
Inlet Port (Flush Back) .................................... 1” NPTF (1” NPTF)
Discharge Port (Extended Front) ............... 1” NPTF (1” NPTF)
By-Pass Port (Flush Bottom) ........................ 1” NPTF (1” NPTF)
Maximum Operating Temperature:
Standard Buna o-rings ........................................140°F (60°C)
Standard Buna o-rings (intermittent) ...........195°F (90°C)
Optional FPM o-rings ..........................................240°F (116°C)
Weight .................................................................4.46 lbs. (2.02 kg)
Dimensions .................................. 8.85 x 5.08 x 1.625” (225 x 129 x 41 mm)
Unloader is stamped with a European safety pressure. Use only at above
specifications to assure proper unloader life and performance.
For Relief Valve version add .100 to unloader model number.
FEATURES
l Maintains full system pressure while running
in by-pass without full load on pump.
l Offers pump protection against pressure
fluctuations and system changes.
l Minimum pressure fluctuations with alternating
use of multiple guns.
l Easy external pressure adjustment with locking
nut to prevent over pressure.
l Lightweight flow through design for compact
installation.
All High Pressure Systems require a primary pressure regulating device (i.e. regulator,
unloader) and a secondary pressure relief device (i.e. pop-off valve, relief valve). Failure
to install such relief devices could result in personal injury or damage to pump or
property. CAT PUMPS does not assume any liability or responsibility for the operation
of a customer’s high pressure system.
Read all CAUTIONS and WARNINGS before commencing service or operation of any
high pressure system. The CAUTIONS and WARNINGS are included in each service
manual and with each Accessory Data sheet. CAUTIONS and WARNINGS can also be
viewed online at www.catpumps.com/cautions-warnings or can be requested directly
from CAT PUMPS.

SELECTION
This is a pressure sensitive regulating unloader. Designed for systems
with single or multiple pumps, solenoid (gate) valves, nozzles, standard or
“weep” guns.
Note: For multiple pump systems, it is best to use a pressure regulator
not a pressure sensitive regulating unloader.
This pressure sensitive regulating unloader should meet both the desired
system flow (combined nozzle flow rate requirement) and the desired
system pressure.
CAUTION: When operating multiple guns, be certain to establish a
minimum of 10 GPM per gun to avoid cycling of the unloader.
Note: Operation below the minimum flow of the unloader causes the
unloader to cycle. Operation above the maximum flows of the unloader
causes premature unloader wear, cycling and prevents attaining desired
system pressure.
INSTALLATION
This unloader operates properly when mounted in any direction,
however, it is preferred to keep the plumbing to a minimum and the
pressure adjuster/adjusting handle easily accessible. The best mounting
location is directly on the pump discharge manifold head.
The inlet connection on this unloader is a 1” NPTF sized port and is
located on the back side. There is an arrow and the word IN cast into the
body indicating the direction of flow. Fluid from the discharge of the
manifold goes through this connection.
The discharge connection on this unloader is a 1” NPTF sized port and is
located on the front side (hex end). There is an arrow and the word OUT
cast into the body indicating the direction of flow. Plumbing for the spray
guns, solenoid (gate) valves or nozzles are connected here.
The by-pass connection of this unloader is a 1” NPTF sized port and is
located on the bottom. There is an arrow and the word BY PASS cast into
the body indicating the direction of flow. By-Pass fluid is directed out of
this port and can be routed to a reservoir (preferred method), or to a drain
or to the pump inlet.
OPERATION
This pressure sensitive regulating unloader holds established system
pressure in the discharge line when the trigger gun is closed or solenoid
(gate) valve is closed or the nozzle is clogged, thus by-passing all
unrequired flow. Squeezing the trigger gun or opening the solenoid
(gate) valve will close off the by-pass and return to established system
pressure without delay.
PRESSURE ADJUSTMENT
1. Setting and adjusting the unloader pressure must be done with the
system “on”.
2. Start the system with unloader backed off to the lowest pressure
setting (counterclockwise direction).
3. Squeeze the trigger and read the pressure on the gauge at the pump.
Note: Do not read the pressure at the gun or nozzle.
4. If more pressure is desired, release the trigger, turn pressure adjuster/
adjusting handle one quarter turn in clockwise direction.
5. Squeeze the trigger and read the pressure.
6. Repeat this process until desired system pressure is attained.
7. Once the desired system pressure is reached, stop turning the
pressure adjuster/adjusting handle.
8. Thread locking nut down to spring retainer.
Note: Locking nut is not set at the factory.
CAUTION: A minimum by-pass flow of 5% of the unloader rated flow
capacity is required for proper unloader performance. If the entire out is
directed through the unloader (zero by-pass) the “cushioning” feature of
the by-pass liquid is eliminated and the unloader can malfunction or wear
prematurely.
9. If desired system pressure cannot be reached, review
TROUBLESHOOTING chart.
10. When servicing existing systems, back locking nut away from spring
retainer.
11. Follow adjustment procedures as stated above for new unloaders.
Note: Do not adjust unloader pressure setting to compensate for a worn
nozzle. Check the nozzle as part of the regular maintenance and replace
if worn.
Note: A secondary pressure safety relief device (i.e. pop-off valve, safety
valve) should be used along with this pressure sensitive regulating
unloader. Final adjustment for the relief valve should relieve at 200 psi
above the system operating pressure.
TYPICAL UNLOADER INSTALLATION
1 Relief Valve
Show as a secondary safety relief valve
2 Pressure Gauge
3 Triplex Plunger Pump
4 Pressure Sensitive Regulating Unloader
5 Pulsation Dampener
5
4
DISCHARGE
3
BY-PASS
1
2
INLET
Read all CAUTIONS and WARNINGS before commencing
service or operation of any high-pressure system

SERVICING
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.
Disassembly:
1. Disconnect by-pass, discharge and inlet plumbing from unloader.
2. Remove unloader from pump.
3. Secure lower body of unloader in a vise with pressure adjuster/
adjusting handle facing up.
4. Remove discharge fitting and o-ring, spring, check valve and o-ring.
5. Inspect check valve and discharge fitting for wear, spring for wear or
fatigue and o-rings for cuts or wear and replace as needed.
Note: While the discharge fitting is removed, inspect sealing area where
the check valve makes contact within the internal body of the unloader
for grooves, pitting and wear. If damage is found, stop the repair and
replace with complete new unloader. If not, proceed with disassembly.
6. Unscrew and remove pressure adjuster/adjusting handle, locking
nut, spacer (7592 only), spring retainer, upper spring retainer, spring,
lower spring retainer and ball. Inspect all parts for scale build up or
wear and replace as needed. Examine spring for fatigue or wear and
replace as needed.
7. Unscrew upper body from lower body.
8. Secure the valve on the flat surfaces and using an 8mm allen wrench
unthread the piston stem from the valve.
9. Remove piston retainer, o-rings and back-up-ring. Examine piston
retainer for wear. Examine o-rings and back-up-ring for cuts or wear
and replace as needed.
10. Examine the valve and piston stem for wear. Examine o-rings and
back-up-rings for cuts or wear and replace as needed.
11. Press the seat out of the lower body from the by-pass port. Examine
seat for grooves and o-ring for cuts or wear and replace as needed.
Reassembly:
1. Lubricate and install o-ring on outside diameter of seat and press seat
squarely into position in the lower body.
2. Lubricate and install o-ring and then back-up-ring onto piston stem.
Press piston stem with threads facing down into the top end of the
upper body.
3. Lubricate and install back-up-ring and then o-ring into inside
diameter of piston retainer. Insert piston retainer into the bottom of
the upper body.
4. Apply Loctite®242® to the threads of the piston stem and valve. Thread
valve onto piston stem and tighten with wrench.
5. Lubricate and install o-ring on to bottom of the upper body. Carefully
hand thread upper body into lower body and tighten with a wrench.
6. Replace the ball, lower spring retainer, spring, upper spring retainer,
spring retainer and spacer (7592 only) into top of upper body.
7. Thread in locking nut and pressure adjuster/adjusting handle.
8. Lubricate and install o-ring onto check valve. Place spring inside
check valve. Insert check valve with o-ring and spring into discharge
port of lower body.
9. Lubricate and install o-ring onto threaded end of discharge fitting.
Thread in discharge fitting to discharge port of lower body and
tighten with wrench.
10. Remove unloader from vise.
11. Re-install unloader onto pump.
12. Reconnect by-pass, discharge and inlet plumbing to unloader.
13. Proceed to PRESSURE ADJUSTMENT.
Loctite® 242® are registered trademarks of the Henkel Corporation.
TROUBLESHOOTING
Unloader cycles l Check for leak downstream of unloader.
l Worn O-ring or check valve.
l Air in system, poor connection.
l O-ring in gun worn.
l Insufficient flow through unloader.
Liquid leaking from l O-ring for fitting cut or worn.
bottom fitting l O-ring for seat cut or worn.
Liquid leaking from l O-ring for piston worn or cut.
middle l O-rings for piston stem worn or cut.
Unloader will not come l Not properly sized for system pressure.
up to pressure l Foreign material in unloader. Clean filter.
l Piston stem O-rings worn.
l Nozzle worn.
l Insufficient flow to pump.
Extreme pressure l Adjusting nut turned completely
spikes into unloader.
l Restricted by-pass or no by-pass.
l System flow exceeds unloader rating.
Filtration l Clean filter on regular schedule to
avoid cavitation.
Approximate Gauge Gauge
Pressure Reading Between Between
at Gauge Pump/Unloader Unloader/Gun-Nozzle-Valve
System in operation system pressure system pressure
(gun open)
System in by-pass low pressure system pressure
(all guns,valves closed) 0-150 PSI +200 PSI
PRESSURE READING
Read all CAUTIONS and WARNINGS before commencing
service or operation of any high-pressure system

ITEM PN MATL DESCRIPTION QTY
402 33089 NY Handle, Adjusting w/Screw 1
403 39061 STZP Adjuster, Pressure (M10x42) 1
404 — STZP Nut, Hex Locking (M10) (7590) 1
406 — AL Spacer (7592) 1
407 39062 BB Retainer, Spring 1
408 39016 STL R Spring (Silver) 1
409 32781 BB Retainer, Spring, Upper 1
410 32778 BB Retainer, Spring, Lower 1
412 32776 S Stem, Piston 1
414 — PTFE Back-up-Ring, Piston Stem 1
415 — NBR O-Ring, Piston Stem 1
417 31075 SSSS Ball, Seat 1
425 — BB Body, Upper 1
427 32777 BB Retainer, Piston 1
428 — NBR O-Ring, Upper Body 1
ITEM PN MATL DESCRIPTION QTY
429 — NBR O-Ring, Piston 1
430 — PTFE Back-up-Ring, Piston 1
431 — NBR O-Ring, Piston Retainer 1
435 32774 S Valve 1
436 32775 S Seat 1
437 32926 NBR O-Ring, Seat - 95D 1
440 — BB Body, Lower 1
441 — NBR O-Ring, Check Valve 1
443 32779 BB Valve, Check 1
444 32782 S Spring, Check Valve 1
446 — NBR O-Ring, Discharge Fitting 1
460 32780 BB Fitting, Discharge (1” NPTF) 1
468 32773 NBR Kit, O-Ring 1
(Inclds: 414, 415, 428, 429, 430, 431, 437, 441, 446)
EXPLODED VIEW
Italics are optional items. R Components comply with RoHS Directive.
AL=Aluminum BB=Brass NBR=Medium Nitrile (Buna-N) NY=Nylon PTFE=Pure Polytetrafluoroethylene
S=304SS SSSS=440SS STL=Steel/Zinc Plated
412 403
404
407
409
408
410
417
441
443
444
446
460
402
414
415
425
428
429
430
427
431
435
436
437
440
Inlet By-Pass
Discharge
CAT PUMPS
1681  94TH LANE N.E. MINNEAPOLIS, MN 554494324
PHONE 763 7805440  FAX 763 7802958
e-mail: [e-mail]
www.catpumps.com
For International Inquiries go to www.catpumps.com and navigate to the “Contact Us” link. PN 993190 Rev C 10/11 101121
406
PARTS LIST