Graco GX-8 Quick start guide

Graco Inc. P.O. Box 1441 Minneapolis, MN 55440-1441
Copyright 2006, Graco Inc. is registered to I.S. EN ISO 9001
311338B
Operation, Parts, Service, Repair
GX-8P Spray Gun
For use with non-flammable polyurethane foams, two-component coating
systems (polyureas), and some two-component epoxy systems.
Not for use in explosive atmospheres.
3500 psi (24 MPa, 240 bar) Maximum Working Pressure
125 psi (90 KPa, 9 bar) Maximum Air Working Pressure
Important Safety Instructions
Read all warnings and instructions
in this manual. Save these instructions.
GX-8 Model 297898
GX-8P Auto Model 297860

2311338B
Contents
Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Overall View . . . . . . . . . . . . . . . . . . . . . . . . 5
Centerline Components . . . . . . . . . . . . . 5
Mixing Module . . . . . . . . . . . . . . . . . . . . 6
Operation Basics . . . . . . . . . . . . . . . . . . . . 7
Isocyanate Hazard . . . . . . . . . . . . . . . . . 7
Keep A and B Components Separate . . 7
Grounding . . . . . . . . . . . . . . . . . . . . . . . . 7
Safety Position . . . . . . . . . . . . . . . . . . . . 7
Air Hose Connection . . . . . . . . . . . . . . . 8
Coupling Block . . . . . . . . . . . . . . . . . . . . 8
Air Inlet Configuration . . . . . . . . . . . . . . 10
Mixing Module and PCD Installation . . 10
Valving Rod Adjustment . . . . . . . . . . . . 11
Initial Set Up . . . . . . . . . . . . . . . . . . . . . 12
Daily Start-up . . . . . . . . . . . . . . . . . . . . 13
Daily Shutdown . . . . . . . . . . . . . . . . . . 13
Pressure Relief Procedure . . . . . . . . . . . 14
Maintenance . . . . . . . . . . . . . . . . . . . . . . . 15
Gun Service Kits . . . . . . . . . . . . . . . . . 15
Clean Spray Gun Procedure . . . . . . . . 15
Flush Gun . . . . . . . . . . . . . . . . . . . . . . . 16
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Service Screen Screw . . . . . . . . . . . . .17
Remove Check Valve . . . . . . . . . . . . . .17
Remove Centerline Components . . . . .18
Install Centerline Components . . . . . . .18
Replace End Cap and Air Piston Assembly
19
Replace Trigger Valve O-Rings . . . . . . .22
Clean Mixing Module . . . . . . . . . . . . . .23
Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
GX-8 Gun Final Assembly (297898) . . .24
GX-8 Handle Assembly (297702) . . . . .26
GX-8P Spray Gun Final Assembly
(297860) . . . . . . . . . . . . . . . . . . . . .28
GX-8P Auto Cylinder Assembly (297861)
30
Auto GX-8P Optional Parts . . . . . . . . . .32
Coupling Block Assembly (295383) . . .33
Coupling Block (297902) . . . . . . . . . . .34
Set-up Chart for GX-8P Modules . . . . .35
GX-8P Model Specifications . . . . . . . . .36
Tool Kits . . . . . . . . . . . . . . . . . . . . . . . .36
Technical Data . . . . . . . . . . . . . . . . . . . . .37
Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Graco Standard Warranty . . . . . . . . . . . .39
Graco Information . . . . . . . . . . . . . . . . . .40

Warnings
311338B 3
Warnings
The following general warnings are for the setup, use, grounding, maintenance, and repair of this
equipment. Additional, more specific warnings may be found throughout the body of this manual
where applicable. Symbols appearing in the body of the manual refer to these general warnings.
When these symbols appear throughout the manual, refer back to these pages for a description
of the specific hazard.
WARNING
PERSONAL PROTECTIVE EQUIPMENT
You must wear appropriate protective equipment when operating, servicing, or when in the
operating area of the equipment to help protect you from serious injury, including eye injury,
inhalation of toxic fumes, burns, and hearing loss. This equipment includes but is not limited to:
• Protective eyewear
• Clothing and respirator as recommended by the fluid and solvent manufacturer
•Gloves
• Hearing protection
TOXIC FLUID OR FUMES HAZARD
Toxic fluids or fumes can cause serious injury or death if splashed in the eyes or on skin,
inhaled, or swallowed.
• Read MSDS’s to know the specific hazards of the fluids you are using.
• Store hazardous fluid in approved containers, and dispose of it according to applicable
guidelines.
SKIN INJECTION HAZARD
High-pressure fluid from gun, hose leaks, or ruptured components will pierce skin. This may
look like just a cut, but it is a serious injury that can result in amputation. Get immediate surgi-
cal treatment.
• Do not point gun at anyone or at any part of the body.
• Do not put your hand over the spray tip.
• Do not stop or deflect leaks with your hand, body, glove, or rag.
• Do not spray without tip guard and trigger guard installed.
• Engage trigger lock when not spraying.
•FollowPressure Relief Procedure in this manual, when you stop spraying and before
cleaning, checking, or servicing equipment.
PRESSURIZED EQUIPMENT HAZARD
Fluid from the gun/dispense valve, leaks, or ruptured components can splash in the eyes or on
skin and cause serious injury.
•FollowPressure Relief Procedure in this manual, when you stop spraying and before
cleaning, checking, or servicing equipment.
• Tighten all fluid connections before operating the equipment.
• Check hoses, tubes, and couplings daily. Replace worn or damaged parts immediately.

Warnings
4311338B
FIRE AND EXPLOSION HAZARD
Flammable fumes, such as solvent and paint fumes, in work area can ignite or explode. To
help prevent fire and explosion:
• Use equipment only in well ventilated area.
• Eliminate all ignition sources; such as pilot lights, cigarettes, portable electric lamps, and
plastic drop cloths (potential static arc).
• Keep work area free of debris, including solvent, rags and gasoline.
• Do not plug or unplug power cords, or turn power or light switches on or off when flammable
fumes are present.
• Ground all equipment in the work area. See Grounding instructions.
• Use only grounded hoses.
• Hold gun firmly to side of grounded pail when triggering into pail.
• If there is static sparking or you feel a shock, stop operation immediately. Do not use
equipment until you identify and correct the problem.
• Keep a working fire extinguisher in the work area.
EQUIPMENT MISUSE HAZARD
Misuse can cause death or serious injury.
• Do not operate the unit when fatigued or under the influence of drugs or alcohol.
• Do not exceed the maximum working pressure or temperature rating of the lowest rated
system component. See Technical Data in all equipment manuals.
• Use fluids and solvents that are compatible with equipment wetted parts. See Technical
Data in all equipment manuals. Read fluid and solvent manufacturer’s warnings. For com-
plete information about your material, request MSDS forms from distributor or retailer.
• Check equipment daily. Repair or replace worn or damaged parts immediately with genuine
Graco/Gusmer replacement parts only.
• Do not alter or modify equipment.
• Use equipment only for its intended purpose. Call your Graco/Gusmer distributor for infor-
mation.
• Route hoses and cables away from traffic areas, sharp edges, moving parts, and hot sur-
faces.
• Do not kink or over bend hoses or use hoses to pull equipment.
• Keep children and animals away from work area.
• Comply with all applicable safety regulations.
PRESSURIZED ALUMINUM PARTS HAZARD
Do not use 1,1,1-trichloroethane, methylene chloride, other halogenated hydrocarbon solvents
or fluids containing such solvents in pressurized aluminum equipment. Such use can cause
serious chemical reaction and equipment rupture, and result in death, serious injury, and prop-
erty damage.
WARNING

Overall View
311338B 5
Overall View
Centerline Components
125 PSI MAX
Trigger
Air Cap Air
Adjustment
Valve
Safety Stop
Gun Block
Air Cap
Gun Block
Manual
Coupling
Mounting Screw
Valves
Block
FIG. 1: GX-8P Overall View
B-Screen Screw
Screen
Gun Block
Screen
Mixing
Pattern Control
PCD
Air Cap
B-Check
Coupling Coupling Block
A-Check
Screen
A-Screen
Screen
Rear Seal
Packing Nut
Valving Rod
Jam Nut
O-Ring
Module
Disc (PCD)
Retainer
Valve
Block Gasket Mounting Screw
Valve
Retainer
Retainer
Screw
Assembly
FIG. 2: GX-8P Centerline Components

Overall View
6311338B
Mixing Module
Graco offers a variety of spray tip configura-
tions to meet most applications that spray
fast-reaction chemical systems at low outputs.
GX-8P spray tip components consist of a Pat-
tern Control Disc (PCD) and a Mixing Module
(Figure 3). Tip components are available in a
range of sizes in both round and fan spray pat-
terns. Please contact your authorized Graco
distributor to help you determine the best con-
figurations for your specific application.
Valving Rod
Mixing
Pattern
Fan Spray
Assembly
Pattern
Round
Spray Pattern
Module
Control
Disc (PCD)
FIG. 3: Mixing Module & PCD

Operation Basics
311338B 7
Operation Basics
Isocyanate Hazard
Keep A and B Components
Separate
Grounding
Check your local electrical code and propor-
tioner manual for detailed grounding instruc-
tions.
Ground spray gun through connection to
Graco-approved grounded fluid supply hose.
Safety Position
GX-8P guns have a two-position safety stop.
When engaged, it prevents accidental trigger-
ing of gun during servicing or down time. When
disengaged, it allows gun to dispense.
Engage Safety Stop
To engage safety stop, push in and turn safety
stop clockwise to place gun in CLOSED safety
position.
FIG. 4: Safety Stop - Engaged
Disengage Safety Stop
To disengage safety stop, push in and turn
safety stop counterclockwise to place gun in
OPEN position.
FIG. 5: Safety Stop - Disengaged
To prevent accidental gun operation, always
disconnect air supply before servicing gun or
anytime gun is not in use.
Read Material Safety Data Sheet (MSDS) to
know specific hazards of isocyanates. Use
equipment in a well-ventilated area. Wear
respirator, gloves, and protective clothing
when isocyanates are used.
CAUTION
To prevent cross-contamination of gun’s wet-
ted parts, do not interchange A component
(isocyanate) and B component (resin) parts.
Gun is shipped with A side on left.
Engage the
Safety Stop
125 PSI MAX
125 PSI MAX
Disengage the
Safety Stop

Operation Basics
8311338B
Air Hose Connection
Connect Air Hoses
Pull back sleeve of female fitting, insert male
fitting and slide sleeve forward to secure con-
nection.
Disconnect Air Hoses
Pull back sleeve of female fitting and pull out
male fitting.
FIG. 6: Disconnect Air Hose
Coupling Block
Chemical hoses are joined to gun block by a
coupling block to ease installation and removal
of gun.
Manual Valves
Two manual valves located on coupling block
control flow of each chemical component to
gun.
Open Manual Valves
Use 5/16 in. nut driver to turn manual valve
clockwise approximately three full turns.
FIG. 7: Open Manual Valves
Pull Sleeve
Triggering gun with manual valves closed
may cause crossover if any residual
chemical remains in gun ports.
Never open manual valve unless coupling
block is secured to gun or unless you point
gun into waste container.
Coupling
Block
Manual
Valves

Operation Basics
311338B 9
Close Manual Valves
Use 5/16 in. nut driver to turn manual valve
fully counterclockwise.
Installation and Removal
Install Coupling Block
1. Replace nicked, damaged, or worn cou-
pling block gaskets.
2. Ensure A-(isocyanate) and B-(resin) check
valves are inserted into their proper
recesses in gun block. Isocyanate valve is
notched for easy identification.
3. Fit coupling block into gun block and insert
coupling block mounting screw. Use 5/16
in. nut driver to tighten to gun block.
FIG. 8: Install Coupling Block
Remove Coupling Block
1. CLOSE safety stop.
2. Disconnect air hose.
3. Close both manual valves.
4. Remove coupling block mounting screw.
5. Separate coupling block from gun.
6. Wipe mating surfaces of gun block and
coupling block to remove residual chemi-
cals.
7. Cover exposed openings with grease.
CAUTION
To prevent accidental gun operation, always
set safety stop to CLOSED, close both man-
ual valves, and disconnect air supply.
To prevent release of pressurized chemicals,
close both manual valves before coupling
block is removed.
To avoid accidental gun operation, ensure
coupling block manual valves are closed
before attempting to service gun, or any
time gun is not in use.
125 PSI MAX
B-Check
Valve
A-Check
Valve
Coupling Block
Gaskets
Coupling Screw
Mounting Screw

Operation Basics
10 311338B
Air Inlet Configuration
There are two configurations for the air inlet. In
the standard configuration, the air inlet is at
base of handle. In the alternate configuration,
the air inlet is at rear of gun.
FIG. 9: Air Inlet Configuration
To change to alternate configuration:
1. Use 6 in. adjustable wrench to remove 4 in.
pipe nipple from base of gun.
2. Use 3/16 in. hex key to remove 1/8 in. pipe
plug from rear of gun.
3. Use 3/16 in. hex key to install 1/8 in. pipe
plug in location previously occupied by 4 in.
pipe nipple.
4. Use 6 in. adjustable wrench to install pipe
nipple in location previously occupied by
1/8 in. pipe plug.
Mixing Module and PCD
Installation
1. Loosen air cap by hand and remove.
2. Install mixing module:
a. Disconnect gun from coupling block.
b. Connect air supply to gun.
c. Set safety stop to OPEN.
d. Hold down trigger and place module
over tip of valving rod.
e. Align keying pin with slot in gun block
and keep gun trigger held down.
3. Install PCD:
a. Hold down gun trigger and thread PCD
retainer in place by hand.
b. Use 10 in. adjustable wrench to care-
fully tighten PCD retainer until snug
enough to ensure no leak will occur.
c. Release gun trigger.
4. Install air cap and tighten by hand.
5. Adjust valving rod (see Valving Rod
Adjustment, page 11).
125 PSI MAX
Pipe Plug
Optional
Pipe Plug
Pipe
Nipple

Operation Basics
311338B 11
Valving Rod Adjustment
Valving rod should not require adjustment if it
was shipped from factory with mixing module
and PCD installed. Valving rod should only re-
quire adjustment when:
• Piston/rod assembly/ring is changed
• Valving rod is changed
• PCD is installed or changed
• Mixing module is installed or changed
To adjust valving rod:
1. Perform Clean Spray Gun Procedure,(see
page 15.
2. Connect air supply to gun.
3. Use 5/16 in. open-end wrench to loosen
packing nut 3 or 4 turns. This relieves pres-
sure between seals and makes adjustment
easier.
FIG. 10: Valving Rod Adjustments
4. Use 3/8 in. wrench on hex-shaped valving
rod shank and 1/2 in. wrench on jam nut to
loosen and back it away from valving rod by
3 or 4 full turns. Then move valving rod
toward gun cylinder. Turn valving rod shank
2 or 3 full turns clockwise.
5. Slowly turn valving rod counterclockwise to
move it toward PCD until resistance is felt.
Valving rod tip should touch inside spheri-
cal surface of PCD.
6. Carefully maintain 3/8 in. wrench in position
and tighten jam nut up against valving rod
shank to lock adjustment into place.
7. Retighten packing nut.
8. Check rear safety stop by attempting to dis-
engage it. If knob will not turn, valving rod
is adjusted too far forward. Repeat steps 3 -
7. Make sure not to adjust valving rod past
the point resistance is felt. If safety stop dis-
engages, proceed to step 9.
9. Trigger gun with safety stop disengaged to
confirm rear seal adjustment. Make sure
rod moves freely. If not, loosen packing nut
slightly until it does. Start to spray and
check for chemical seepage from packing
nut and retighten if necessary.
Valving Rod
Assembly
Jam Nut
Packing
Nut
If valving rod required adjustment as part of
initial mixing module and PCD installation
on a new spray gun, proceed to Initial Set
Up, page 12.

Operation Basics
12 311338B
Initial Set Up
1. Remove coupling block from gun.
2. Use two 6 in. adjustable wrenches to install
female quick disconnect fitting onto air sup-
ply hose bundled with chemical supply
hoses.
3. Use two 6 in. adjustable wrenches to con-
nect A-isocyanate hose (red-taped) to
notched fitting on coupling block. Connect
B-resin hose (blue-taped) to fitting without
notches on coupling block.
4. Close both manual valves.
5. Pressurize A and B chemical hoses and
check for leaks (see Proportioner manual
as needed).
6. Bleed air from chemical hoses:
a. Hold coupling block with exit ports
pointed into waste container.
b. Use 5/16 in. nut driver to open each
manual valve; this allows any trapped
air to escape. Bleed each side for a
short time until chemicals leaving hoses
are free of air.
c. Close both manual valves.
7. Use cloth soaked in gun cleaner to clean
coupling block and mating surfaces.
8. CLOSE safety stop.
9. Install coupling block to gun.
10.Proceed with daily start-up and shutdown
procedures as required.
CAUTION
Do not apply grease to mating surfaces of
coupling block to avoid accumulation of dirt
and other contaminants.

Operation Basics
311338B 13
Daily Start-up
1. Connect air supply to gun.
2. Adjust air cap adjustment valve. Turn knob
counterclockwise to open valve and clock-
wise to close valve.
3. Open both manual valves.
4. OPEN safety stop.
5. Test spray on a disposable surface and
evaluate.
Daily Shutdown
1. CLOSE safety stop.
2. Close both manual valves.
3. Disconnect air supply from gun.
4. Shut down proportioning unit as required.
5. Clean as required (see Clean Spray Gun
Procedure, page 15).
Ensure gun is attached to coupling block and
air hose. Ensure proportioning unit is at
desired temperature and pressure. Properly
ground equipment to avoid static sparking
that may result in fire or explosion.
Follow daily shutdown procedure when
gun is out of service for any length of time,
or for mid- or end-of-day service. See
Clean Spray Gun Procedure, page 15.
Disassembling gun for daily cleaning is not
recommended if gun has been operating
properly. However, if gun is removed from
coupling block, it must be flushed and
cleaned thoroughly.

Pressure Relief Procedure
14 311338B
Pressure Relief
Procedure
1. Close both manual valves.
FIG. 11: Close Manual Valves
2. OPEN safety stop.
3. Trigger gun onto cardboard or into waste
container to relieve pressure.
FIG. 12: Trigger Gun
4. Release gun trigger, CLOSE safety stop,
and close manual valves.
FIG. 13: Open Manual Valves
Relieve pressure before cleaning or repairing
gun.
Manual Valves
!
2
If fluid in hose and proportioner is still under
pressure, follow Pressure Relief Procedure in
proportioner manual
To relieve pressure in hose after gun is
removed, place fluid manifold over containers,
facing away from you. Very carefully open
fluid valves (FIG. 13). Under high pressure,
fluid will spray sideways from fluid ports.

Maintenance
311338B 15
Maintenance
Gun Service Kits
Use either 1-Quart Gun Service Kit (296980)
or 3-Gallon Gun Service Kit (296981) to per-
form daily flushing of spray gun without disas-
sembly.
FIG. 14: 1-Quart Gun Service Kit
For more information about 1-Quart Gun Ser-
vice Kit, see Manual 311340.
FIG. 15: 3-Gallon Gun Service Kit
For more information about 3-Gallon Gun Ser-
vice Kit, see Manual 311341.
Clean Spray Gun Procedure
Thoroughly flush gun block with gun cleaner
before removing valving rod or mixing compo-
nents from gun block. Also allow chemicals in
spray gun to cool before cleaning.
This procedure makes use of the 1-Quart or
3-Gallon Gun Service Kit.
1. CLOSE safety stop.
2. Close both manual valves.
3. Remove gun from coupling block.
To avoid static sparking that may result in fire
or explosion, ensure all equipment in cleaning
procedure is grounded. Do not clean on or
near foamed or coated surfaces or any other
flammable surfaces or objects.

Maintenance
16 311338B
4. Attach service block of gun service kit to
spray gun, and then tighten using 5/16 in.
nut driver.
5. Pressurize service kit container up to 100
psi. DO NOT EXCEED 100 psi (0.7 MPa, 7
bar).
6. Clean gun:
a. Set safety stop to OPEN.
b. Open either manual valve on service
block.
c. Trigger gun and gun service kit simulta-
neously with gun aimed into waste con-
tainer.
d. Release both triggers and close manual
valves on service block.
e. Repeat procedure for other side of gun.
f. After initial cleaning, remove air cap,
PCD retainer, and PCD. Flush a second
time to ensure thorough cleaning.
7. CLOSE safety stop.
8. Disconnect air supply from gun.
9. Remove service block of gun service kit
from gun.
10.Clean screens, check valves and screen
screw (see Service Screen Screw, page
17.
Flush Gun
1. CLOSE safety stop.
2. Close both manual valves.
3. Loosen B-Screen screw and then remove
by hand.
4. Use flush can to thoroughly flush screen
screw and screen screw cavity.
5. Loosen A-Screen screw and then remove
by hand.
6. Use flush can to thoroughly flush screen
screw and screen screw cavity.
7. Service gun, see Maintenance proce-
dures, page 15.
Inspect air cap, PCD, mixing module, and
gun block for build up of material and clean
as required.
Do not use metal cleaning devices to clean
plastic components.
To avoid static sparking that may result in fire
or explosion, ensure all equipment in flushing
procedure is grounded. Do not flush on or
near foamed or coated surfaces.

Repair
311338B 17
Repair
Service Screen Screw
1. Flush gun see Clean Spray Gun Proce-
dure, page 15.
2. Unthread screen screw from gun block.
3. Remove screen screw retainer before
removing screen.
4. Remove screen from screen screw. Soak in
gun cleaner or replace if clogged or dirty.
5. Clean screen screw cavity. If any particles
are visible, clean with clean out drills and
flush with gun cleaner.
6. Inspect screen screw seal for damage.
Replace if necessary.
7. Reinstall screen screw in gun block. Ensure
it is tight.
8. Flush gun with mixing module removed.
Remove Check Valve
Check valves are located in cavities of gun
block under each coupling block gasket. Check
valves are triangular pieces with a spring insert-
ed in one end. The isocyanate valve is notched
for easy identification.
To remove check valve:
1. Clean gun (see Clean Spray Gun Proce-
dure, page 15).
2. Use check valve seal removal/cleaning tool
to remove gaskets from recesses in cou-
pling block. Inspect gaskets for damage
and replace if necessary.
3. Remove check valves. If valve does not
come out easily, insert machined end of
removal/cleaning tool over valve and rotate
it while extracting valve.
4. Clean valves and springs with gun cleaner.
Inspect for damage and replace if neces-
sary.
5. Inspect each check valve cavity. Use clean-
ing tool to remove any visible particles. Use
gun cleaner to flush thoroughly.
6. Insert each check valve into its cavity
spring end first. Ensure check valve is ori-
ented correctly. Isocyanate valve is notched
for easy identification.
7. Install coupling block gaskets.
Shutdown proportioner and allow chemicals
to cool before servicing gun.
To avoid static sparking that may result in fire
or explosion, ensure all equipment in flushing
procedure is grounded. Do not flush on or
near foamed or coated surfaces.
Any material left in cavity on downstream
side of screen will clog mixing module.
To avoid static sparking that may result in fire
or explosion, ensure all equipment in flushing
procedure is grounded. Do not flush on or
near foamed or coated surfaces.

Repair
18 311338B
Remove Centerline
Components
Refer to page 5 for diagrams of centerline
components for all gun models.
1. Flush gun (see Clean Spray Gun Proce-
dure, page 15).
2. Remove air cap (loosen by hand).
3. Use 10 in. adjustable wrench to remove
PCD.
4. Connect air supply to gun.
5. Lift PCD off nose of gun block and remove.
6. Remove mixing module retainer.
7. OPEN safety stop. Depress and release
gun trigger to unseat it. Remove mixing
module off end of valving rod. CLOSE
safety stop.
8. Disconnect air supply from gun.
9. Use 5/16 in. wrench to loosen packing nut
3 or 4 turns.
10.Remove gun block:
a. Use 5/16 in. nut driver to remove gun
block retaining screw.
b. Slide gun block away from valving rod
and air cylinder. If dried chemical is built
up on gun block, remove dried chemi-
cals to make removal easier.
11.Remove and clean check valves (see
Remove Check Valve, page 17).
12.Remove valving rod:
a. Use 3/8 in. wrench on hex-shaped valv-
ing rod shank and a 1/2 in. wrench on
jam nut to loosen it and back it away
from valving rod shank by 3 or 4 full
turns.
b. Unthread valving rod from piston shaft
and remove.
13.Clean all components thoroughly before
reassembly.
14.Inspect gun block to ensure proper opera-
tion of spray gun.
Install Centerline
Components
Before installation, ensure all gun components
are clean and dry. Lubricate all moving parts
and threads.
1. To install valving rod, thread jam nut as far
back on piston shaft as possible. Screw
shank end of valving rod onto threaded end
of piston rod.
2. Install rear seal and packing nut if removed.
Thread packing nut into gun block by hand,
but do not tighten.
3. To install gun block, carefully slide gun
block onto valving rod towards air cylinder.
Use 5/16 in. nut driver to install gun block
onto gun block mounting bracket.
4. Connect air supply to gun.
To remove PCD that is stuck, set safety
stop to OPEN, depress and release gun
trigger to unseat it. CLOSE safety stop.
CAUTION
Do not use sharp objects or metal tools to
remove mixing module.

Repair
311338B 19
5. OPEN safety stop.
6. To install mixing module, hold down gun
trigger and slide module over end of valving
rod. Make sure to align keypin with slot in
gun block. Keep gun trigger depressed and
proceed to step 7.
7. To install PCD, hold gun trigger in and
place PCD over mixing module. If installing
a fan tip, position PCD according to which
spray direction is needed (vertical or hori-
zontal). Keep gun trigger depressed and
proceed to step 8.
8. Install PCD retainer:
a. With gun trigger depressed, thread
PCD retainer in place by hand.
b. Use 10 in. adjustable wrench to care-
fully tighten PCD retainer until it is snug
enough to ensure no leak will occur.
c. Release gun trigger.
9. Install air cap and tighten by hand.
10.Adjust valving rod (see Valving Rod
Adjustment, page 11).
Replace End Cap and Air
Piston Assembly
FIG. 16: End Cap and Air Piston Assembly
1. Clean gun (see Clean Spray Gun Proce-
dure on page 15).
2. Disconnect air supply from gun.
3. Use 5/16 in. wrench to loosen packing nut
3 or 4 turns (remove nut completely if rear
seal needs to be replaced).
4. Remove gun block:
a. Use 5/16 in. nut driver to remove gun
block mounting screw.
b. Carefully slide gun block away from
valving rod and air cylinder. If dried
chemical has built up on gun block,
remove dried chemical to make removal
easier.
c. Remove valving rod and jam nut (see
Remove Check Valve, page 17):
Parts must align properly or chemical flow
from gun block ports will not enter mixing
module when gun is triggered.
CAUTION
To avoid damage to module and gun block,
do not overtighten mixing module retainer.
End Cap
Retaining
Ring
End Cap/Safety
Stop Assembly O-Ring
Cylinder
Cup Seal
#8 Socket Head
Cap Screw
Piston
Spring
Piston
Piston
O-Ring

Repair
20 311338B
d. Use 3/8 in. wrench on hex-shaped valv-
ing rod shank and 1/2 in. wrench on jam
nut.
e. Loosen jam nut and back it away from
valving rod shank by 3 or 4 full turns.
f. Unthread valving rod and jam nut from
piston shaft.
5. OPEN safety stop.
6. Use 9/64 in. ball point hex key to remove
socket head cap screw that holds air cylin-
der to handle (FIG. 16).
7. Use retaining ring 45° pliers to remove
retaining ring that holds end cap in place
inside air cylinder.
8. Remove end cap/safety stop assembly and
piston spring:
a. Pull safety stop and attached end cap
out of air cylinder.
b. Remove piston spring located inside
cylinder. Be sure to retain spring for
reinstallation.
9. Inspect end cap ring. Replace if damaged.
Apply light coating of Lubriplate grease and
install new end cap ring.
a. Remove piston/rod assembly:
Use gun block mounting screw (screw
that holds gun block to bracket) to aid in
removal of piston.
b. Look into rear of air cylinder and thread
mounting screw into center hole of pis-
ton at least 4 full turns.
c. Use 6 in. pliers to grab mounting screw
and pull piston rod assembly out of air
cylinder.
d. Inspect ring and replace if damaged.
Apply light coat of Lubriplate grease
and install new ring.
10.Inspect air cylinder cup seal. If air escapes
around piston rod during operation, remove
and replace cup seal located in front of air
cylinder. Lubricate new cup seal with
Lubriplate grease and install it. Make sure
cup faces toward rear of cylinder.
11.Insert piston and rod assembly into air cyl-
inder. Be careful not to damage cup seal in
front face of air cylinder as rod passed
though. Remove gun block mounting screw
from piston.
12.Disassemble safety stop mechanism:
a. Use 5/64 in. hex key to remove two set
screws from knob.
b. Slide knob off stop pin and retain stop
pin spring.
c. Pull shaft out of end cap (FIG. 17).
13.Remove cup seal from end cap and inspect
for damage. Remove if damaged. Apply
light coat of Lubriplate grease and install
new end cap ring.
Force will be required to remove end cap
because ring is tightly compressed.
Skip steps 11-13 and go to step 14 if only
end cap ring and cup seal need to be
replaced.