Graco 26D274 User manual

3A8814A
EN
Instructions
MDX Dispense Valve
Dispense valve for controlling material flow of adhesives, sealants, and other materials
that are compatible with the wetted parts of the valve. For professional use only.
Not approved for use in European explosive atmosphere locations.
Model 26D274
3/4 in. npt Dispense Valve
3000 psi (20.68 MPa, 206.8 bar) Maximum Fluid Working Pressure
100 psi (0.7 MPa, 7 bar) Maximum Air Working Pressure
Important Safety Instructions
Read all warnings and instructions in this
manual before using the equipment.
Save these instructions.

23A8814A
Contents
Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Component Identification . . . . . . . . . . . . . . . . . . . . 5
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . 6
Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Flush Before Using Equipment . . . . . . . . . . . . . . 7
Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Pressure Relief Procedure . . . . . . . . . . . . . . . . . . 9
Adjust Stroke . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Check Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Packing Lubrication . . . . . . . . . . . . . . . . . . . . . . 10
Factors Affecting Valve Life . . . . . . . . . . . . . . . . 11
Recycling and Disposal . . . . . . . . . . . . . . . . . . . . . 12
End of Product Life . . . . . . . . . . . . . . . . . . . . . . 12
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Disconnect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3/4 in. npt Fluid Section . . . . . . . . . . . . . . . . . . . 17
3/4 in. npt Air Section. . . . . . . . . . . . . . . . . . . . . 18
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Grease Gun, 551189 . . . . . . . . . . . . . . . . . . . . . 19
Mixer, 513375 . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Fitting, 122639 . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Technical Specifications . . . . . . . . . . . . . . . . . . . . 21
California Proposition 65. . . . . . . . . . . . . . . . . . . . 21
Graco Standard Warranty . . . . . . . . . . . . . . . . . . . 22

Warnings
3A8814A 3
Warnings
The following warnings are for the setup, use, grounding, maintenance, and repair of this equipment. The
exclamation point symbol alerts you to a general warning and the hazard symbols refer to procedure-specific risks.
When these symbols appear in the body of this manual or on warning labels, refer back to these Warnings.
Product-specific hazard symbols and warnings not covered in this section may appear throughout the body of this
manual where applicable.
WARNING
SKIN INJECTION HAZARD
High-pressure fluid from dispensing device, 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 surgical
treatment.
• Do not point dispensing device at anyone or at any part of the body.
• Do not put your hand over the fluid outlet.
• Do not stop or deflect leaks with your hand, body, glove, or rag.
• Follow the Pressure Relief Procedure when you stop dispensing and before cleaning, checking, or
servicing equipment.
• Tighten all fluid connections before operating the equipment.
• Check hoses and couplings daily. Replace worn or damaged parts immediately.
BURN HAZARD
Equipment surfaces and fluid that is heated can become very hot during operation. To avoid severe
burns:
• Do not touch hot fluid or equipment.

Warnings
43A8814A
FIRE AND EXPLOSION HAZARD
Flammable fumes, such as solvent and paint fumes, in work area can ignite or explode. Paint or
solvent flowing through the equipment can cause static sparking. 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 sparking).
• Ground all equipment in the work area. See Grounding instructions.
• Never spray or flush solvent at high pressure.
• 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.
• Use only grounded hoses.
• Hold gun firmly to side of grounded pail when triggering into pail. Do not use pail liners unless they
are anti-static or conductive.
•Stop operation immediately if static sparking occurs or you feel a shock.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 Specifications in all equipment manuals.
• Use fluids and solvents that are compatible with equipment wetted parts. See Technical
Specifications in all equipment manuals. Read fluid and solvent manufacturer’s warnings. For
complete information about your material, request Safety Data Sheets (SDSs) from distributor or
retailer.
• Turn off all equipment and follow the Pressure Relief Procedure when equipment is not in use.
• Check equipment daily. Repair or replace worn or damaged parts immediately with genuine
manufacturer’s replacement parts only.
• Do not alter or modify equipment. Alterations or modifications may void agency approvals and create
safety hazards.
• Make sure all equipment is rated and approved for the environment in which you are using it.
• Use equipment only for its intended purpose. Call your distributor for information.
• Route hoses and cables away from traffic areas, sharp edges, moving parts, and hot surfaces.
• 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.
PERSONAL PROTECTIVE EQUIPMENT
Wear appropriate protective equipment when in the work area to help prevent serious injury, including
eye injury, hearing loss, inhalation of toxic fumes, and burns. Protective equipment includes but is not
limited to:
• Protective eyewear, and hearing protection.
• Respirators, protective clothing, and gloves as recommended by the fluid and solvent manufacturer.
WARNING

Component Identification
3A8814A 5
Component Identification
A
B
C
D
E
FG
H
J
K
L
A
L
LL
FIG. 1: 3/4 in. npt Dispense Valve - Typical Components
Key:
A Air Connections
B Air Section
C Travel Adjuster
D Lock Nut
E Fluid Section
F Recirculation Port Plug A
G Recirculation Port Plug B
H Fluid Outlet
J Fluid Inlet A
K Fluid Inlet B
L Grease Zerk Fittings

Theory of Operation
63A8814A
Theory of Operation
Air/Open
Air/Close
Fluid Inlet A
Fluid Outlet A
Fluid Inlet B
Fluid Outlet B
Plug A Plug B
FIG. 2: Theory of Operation
The valve uses the air-opened and air-closed mode of
operation, therefore, it uses a four-way exhausting
solenoid to control the piston inside the valve.
The valve has four npt fluid inlet ports. Two fluid inlet
ports are supply ports, feeding material into the
dispense valve. Use other two fluid inlet ports to
recirculate material through the valve, or leave them
plugged with supplied npt plugs. The fluid outlet port
dispenses material through the outlet housing in
regulated amounts.
The air-operated piston, rod, and ball move at the same
time. When air moves the piston, rod, and ball from their
seat, it opens the fluid outlet port. When air pushes the
piston, rod, and ball into their seat, it closes the fluid
port.
The system provides pressurized fluid to the valve and
the system air controls open and close the valve
controlling the fluid flow.

Installation
3A8814A 7
Installation
Grounding
Pump: use ground wire and clamp. Connect ground
clamp to a true earth ground as shown in separate
pump manual.
Air and fluid hoses: use only electrically conductive
hoses with a maximum of 100 ft. (30.5 m) combined
hose length to ensure grounding continuity. Check
electrical resistance of hoses. If total resistance to
ground exceeds 25 megohms, replace hose
immediately.
NOTE: Use a meter that is capable of measuring
resistance at this level.
Air compressor: follow manufacturer’s
recommendations.
Dispense valve: ground through connection to a
properly grounded fluid hose and pump.
Fluid supply container: follow local code.
Solvent pails used when flushing: follow local code.
Use only conductive metal pails placed on a grounded
surface. Do not place the pail on a nonconductive
surface, such as paper or cardboard, which interrupts
grounding continuity.
To maintain grounding continuity when flushing or
relieving pressure: ensure metal part of dispense
valve is in contact with a grounded metal waste
container before actuating the valve.
Flush Before Using Equipment
The equipment was tested with lightweight oil, which is
left in the fluid passages to protect parts. To avoid
contaminating your fluid with oil, flush the equipment
with a compatible solvent before using the equipment.
The equipment must be grounded to reduce the risk
of static sparking. Static sparking can cause fumes to
ignite or explode. Grounding provides an escape wire
for the electric current.

Installation
83A8814A
Mounting
The dispense valves have multiple mounting hole
configurations (see Dimensions, page 20), which make
them ideal for use with robotic equipment or multiple
manifold high production operations.
1. Inspect dispense valve for shipping damage. If there
is damage, notify shipping carrier immediately.
2. Install compatible accessories. For a list of
accessories and installation instructions, see
Accessories, page 19.
NOTE: Follow Pressure Relief Procedure, page 9,
before changing outlet housing.
3. Securely attach the dispense valve to its mounting
fixture using socket head cap screws; see
Dimensions, page 20.
4. Connect air lines to the dispense valve:
a. See Technical Specifications, page 21, for
maximum operating air pressure.
b. Connect air line to air/open air inlet in air section
(B). See FIG. 2, page 6.
c. Connect air line to air/close air inlet in air
section (B). See FIG. 2, page 6.
5. Connect fluid line to npt fluid inlet (J and K) in valve
body. For circulation systems, remove plug from
other inlet (F and G) and connect fluid return line.
See Technical Specifications, page 21, for
maximum operating fluid pressure.
6. Check each fitting to avoid pressure leakage from
the dispense valve.
NOTICE
Only use air fittings that are rated at a temperature
equal to or higher than the operating temperature of
the fluid dispensing system. Lower rated air fittings
could melt and cause damage to the dispense valve.

Operation
3A8814A 9
Operation
Pressure Relief Procedure
Follow the Pressure Relief Procedure whenever
you see this symbol.
This procedure describes how to relieve pressure from
the dispense valve only. See the supply system manual
for instructions on relieving pressure from the entire
system.
1. Shut off material supply.
2. Actuate the valve and dispense fluid into a
grounded metal waste container to relieve the fluid
pressure.
3. Shut off air supply to relieve all air pressure in the
air lines.
4. If the outlet housing or fluid hose is clogged or if
pressure has not been fully relieved after following
the steps above, VERY SLOWLY loosen the npt
inlet fitting from the dispense valve or hose end
coupling to relieve pressure gradually, then loosen
completely. Clear outlet housing or hose
obstruction.
Adjust Stroke
Adjust the distance that the dispense valve opens to
restrict the flow of material through the ball and seat.
See Fig. 4.
1. Loosen the lock nut (D).
2. Cycle air pressure to close valve.
3. Turn the travel adjuster (C) clockwise until the valve
is held closed.
4. Cycle air pressure to open the valve. Ensure
material does not dispense.
5. Slowly open the travel adjuster (C) and then cycle
the air pressure until the desired flow is reached.
6. Tighten lock nut (D) to hold the travel adjuster (C) in
place.
Check Ratio
The output mix ratio of the dispense valve can be
checked by dispensing the two fluids separately out of
the outlet housing into tared cups. Weigh the cups to get
the mix ratio by weight.
Use ratio check nozzles 18F424 with retaining nut
18F425 for 1:1 models to make ratio checks.
Ratio checks provide information on the ratio of an
overall sample. Transient problems (soft spots) caused
by starting and stopping the flow (lead-lag) may not
show up in this kind of ratio check. Physical tests of the
mixed fluid are the best check of correct ratio and mix
quality.
This equipment stays pressurized until pressure is
manually relieved. To help prevent serious injury from
pressurized fluid, such as skin injection, splashing
fluid, and moving parts, follow the Pressure Relief
Procedure when you stop dispensing and before
cleaning, checking, or servicing the equipment.
FIG. 3: 3/4 in. Valve
C
D

Maintenance
10 3A8814A
Maintenance
Inspect the dispense valve, material, and air hoses at
least once every two weeks. Inspect for leakage and
other visible damage daily. If there is any leakage or
damage, change the part immediately. Follow the
Repair, on page 14.
The following table lists recommended maintenance
procedures and frequencies. A typical application is a
valve mounted on a robot dispensing a moderately
abrasive sealant.
* Assumes movement from automation.
Packing Lubrication
This valve has a primary seal, a pressurized grease
area, and a secondary seal. The key to long seal life is
ensuring that the secondary seal only has to seal grease
and is not exposed to other material.
When dispensing filled materials this grease should be
refilled once a month. Complete the following procedure
to avoid pushing grease into the fluid stream
1. Perform the Pressure Relief Procedure, on page
9.
2. Remove two grease zerk fittings (111).
3. Use a grease gun (part no. 551189) to pump a high
quality grease (part no. 115982, high temperature
moisture free) into the grease zerk fitting (111) until
fresh grease comes out the other side.
4. Reinstall the grease zerk fitting (111) and give the
valve one more shot of grease through the grease
zerk fitting (111) to pressurize the cavity.
NOTE: Grease can enter the fluid section if more than
one shot is triggered after the grease zerk fitting or plug
has been replaced.
Task
Weekly
Monthly
or 30,000
cycles
Check hoses for wear* 
Check/tighten fluid connections* 
Check/tighten air connections* 
Check stroke adjustment 
Lubricate packings 
FIG. 4
111