Page 1
Instructions - Parts
312185S
MD2 Valve
For use with disposable mixers to dispense a variety of sealants and adhesives. For
professional use only.
120 psi (0.84 MPa, 8.4 bar) Maximum Air Inlet Pressure
Important Safety Instructions
Read all warnings and instructions in this
manual. Save these instructions.
EN
See page 2 for model information, including maximum working pressure and approvals.
TI9964A
Page 2
MD2 Valve Models
Contents
MD2 Valve Models . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Component Identification . . . . . . . . . . . . . . . . . . . . 5
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Graco Standard Warranty . . . . . . . . . . . . . . . . . . . 30
Graco Information . . . . . . . . . . . . . . . . . . . . . . . . . 30
MD2 Valve Models
MD2 Valves
Maximum Working Pressure
Part No.
255179
255180 1:1 Hard seat, non-adjustable snuff-back
255181 Wide ratio, soft seat, adjustable snuff-back
255182 Wide ratio, hard seat, non-adjustable snuff-back
255183 2000 psi (13.8 MPa, 138 bar) Cold spray/joint fill valve
255206 120 psig (0.84 MPa, 8.4 bar) Air trigger
255208 3A @ 28 VDC Electric air actuated
255249 0.5 @ 28 VDC Electric actuated lever
3000 psi (20.7 MPa, 207 bar
psi (MPa, bar) Description
1:1 Soft seat, adjustable snuff-back
MD2 Valve Handles
Model Selection
The following table provides a summary of the MD2 dispense valves that are described in this manual.
Type Description
Hand held valves with
internal air trigger
Hand held valve with
electric switch
Wide ratio valves The wide ratio MD2 valve has a center injection tip. This feature is helpful with wider
Hard seats Carbide seats and hardened needles are good for abrasive materials and stall against
Soft seats UHMWPE seals are good for precise snuff-back control.
2 312185S
The internal air trigger controls the air piston that operates the MD2 valve. A pilot port
can be used to control a pump motor.
The switch signals the customer’s controller to open and close the ports on the MD2
valve using a remote 4-way air control valve which is not included.
ratio applications, specifically when the low volume material is a much lower viscosity
than the high volume material. Frequent cleaning intervals may be required to maintain
the tip.
pressure applications.
Page 3
Warnings
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 symbol refers to procedure-specific risk. Refer back
to these warnings. Additional, product-specific warnings may be found throughout the body of this manual where
applicable.
WARNING
SKIN INJECTION HAZARD
High-pressure fluid from dispense valve, 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 dispense valve at anyone or at any part of the body.
• Do not put your hand over the end of the dispense nozzle.
• Do not stop or deflect leaks with your hand, body, glove, or rag.
• Follow Pressure Relief Procedure in this manual, when you stop spraying and before cleaning,
checking, or servicing equipment.
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 complete information
about your material, request MSDS forms from distributor or retailer.
• Check equipment daily. Repair or replace worn or damaged parts immediately with genuine manufacturer’s replacement parts only.
• Do not alter or modify equipment.
• 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.
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.
• Always wear impervious gloves when spraying or cleaning equipment.
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
312185S 3
Page 4
Warnings
WARNING
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.
4 312185S
Page 5
Component Identification
F
D
Component Identification
C
B
A
H
G
FIG. 1: Component Identification
Key:
A Snuff-back adjustment knob (soft seat versions only)
B 1/8 in. npt (f) air to close (O).
C 1/8 in. npt (f) air to open (I).
D 9/16 straight thread o-ring boss “B” fluid inlet (low volume)
E 9/16 straight thread o-ring boss “A” fluid inlet (high
volume)
F Zerk grease fitting
G Nosepiece with 7/8-9 bell outlet
H Air cylinder
C
B
E
TI10391A
312185S 5
Page 6
Features
Features
Electric Switch Valve
Series A handle shown
TI10383A
Normally open momentary contact switch
Note: The Trigger/Lever activates an electrical switch in
the handle, which activates a remote 4 way solenoid
valve. Bring an “OPEN” air signal to the 1/8 in. npt(f)
port (I) on this side of the valve, and a “CLOSE” signal
to the port (O). See Accessories, page 23, to order fittings and tubing.
Pneumatic Valve
1/4 in npt (f)
air inlet
TI10407A
The 1/8 in. npt (f) port (I) can be used to send an “ON”
signal back to a pump pilot or control. See F
IG. 1.
Electric Actuated Lever Valve
FIG. 2: Features of the MD2 Valves
TI10409A
6 312185S
Page 7
Installation
Installation
Grounding
The following grounding instructions are minimum
requirements for a basic dispensing system. Your system may include other equipment or objects which must
be grounded. Check your local electrical code for
detailed grounding instructions for your area and type of
equipment. Your system must be connected to a
true-earth ground.
• Pump: ground the pump by connecting ground wire
and clamp as described in your separate pump
instruction manual.
• Air compressors and hydraulic power supplies:
ground the equipment according to the manufac-
turer's recommendations.
• Fluid hoses: use only grounded fluid hoses with a
maximum of 500 feet (150 m) combined hose length
to ensure grounding continuity. Check the electrical
resistance of your fluid hoses at least once a week.
If your hose does not have a tag on it which speci-
fies the maximum electrical resistance, contact the
hose supplier or manufacturer for the maximum
electrical resistance limits, replace the hose immedi-
ately.
• Dispensing valve: ground the valve by connecting
it to a properly grounded fluid hose and pump.
• Fluid supply container: ground according to your
local code.
• Flammable liquids in the dispense area: must be
in approved, grounded containers. Do not store
more than the quantity needed for one shift.
• All solvent pails used when flushing: ground
according to local code. Use only metal pails, which
are conductive. Do not place the pail on a non-con-
ductive surface, such as paper or cardboard, which
interrupts the grounding continuity.
• To maintain grounding continuity when flushing or
relieving pressure, hold a metal part of the valve
firmly to the side of a grounded metal pail, then trig-
ger the valve.
How to Use the Valve Trigger Safety
1. If you are using one of the hand-held versions of the
valve, lock the valve trigger safety by turning the
latch to a right angle with the gun body. See F
2. To unlock the valve trigger safety turn it parallel with
the gun body.
LOCKED
TI10442A
FIG. 3
UNLOCKED
IG. 3.
TI10441A
312185S 7
Page 8
Setup
Setup
Fluid and Air Connections
9/16 Straight Thread O-Ring Boss Fluid
Inlets
There is one fluid inlet on the A-side and one fluid inlet
on the B-side. The fluid inlets are located on the side of
the valve and swivel to permit various mounting and
hose configurations.
1/8 npt(f) Air Inlets
The machine mount valves and the electric switch
hand-held valves have an on port (I) and off port (O),
which are operated by a remote 4-way air control valve.
Use one of the two air inlets located on the bottom and
on the back of the valve.
The air switch hand-held valves have a single air inlet
with an internal 4-way spool which operates the air piston.
See Accessories on page 19, to order air control valves
and tubing.
Inlet Check Valves
Inlet check valves are recommended on the fluid inlets
where viscosity allows. An inlet check valve prevents
back-flow or crossover when the mixer is plugged or one
fluid is much lower viscosity than the other. When
required, a high crack pressure check valve is installed
to maintain back-pressure on low viscosity fluids.
See Accessories on page 19 for a list of check valves.
Balancing the System
Selecting Hoses
Hoses between your proportioner and the MD2 valve
should be selected carefully. Many factors effect hose
selection.
1. Fluid Compatibility: Fluid must not degrade the
core material or end fittings of the hose. Nylon or
PTFE cores are commonly used for chemical compatibility. If your fluid is moisture sensitive you
should use PTFE or Moisture-Lok hoses.
2. Pressure Rating: Be sure hoses have a working
pressure rating above the pressure capability of the
system.
3. Compressibility: Hoses, especially nylon paint
hoses, expand with an increase in pressure. A pressure change in the system may cause a volume
change, which can appear as a ratio error with wide
mix ratios. Compressible hoses absorb pressure
spikes which is helpful to the operator during an
application, such as trying to lay a bead.
4. Internal Diameter: Small I.D.'s create higher back
pressures, lower flows, and small retained volume.
Typically hose I.D.'s are selected for:
a. System Pressure Balance. “A” pressure drop
vs. “B” pressure drop.
b. Volume Balance. A:B volume ratio vs. Hose
retained volume.
c. Flexibility and weight for operator or robot.
d. Overall Pressure Drop. Pressure drop should be
minimum possible within the above guidelines.
A proportioner is used to feed the two-component dispense valve. The system must be pressure balanced to
avoid “lead-lag” ratio errors when starting and stopping
the flow.
Balancing is done by hose sizing or inlet check restriction. A properly balanced system has near equal
back-pressure on the gauges when flowing without a
mixer installed.
8 312185S
5. Length: Hoses normally are kept as short as practical to minimize pressure drop and compressible volume. 10 ft (3.1 m) is recommended for reciprocating
pump systems.
Page 9
System Start-up
When initially loading the fluids through the system,
leave the mixer off until both fluids flow freely from the
nose piece without any air. This prevents cross contamination from having fluid on one side pushing back up the
other side.
Mixer Selection
Disposable mixers are available from 3/16 in. I.D. to 1/2
in. I.D. in lengths from 12 elements to 36 elements. In
general, wide viscosity or mix ratios require more mix
elements. Small I.D. mixers produce lower flow, higher
back-pressure, and waste little material. Large I.D. mixers produce higher flow, lower back-pressure, and fewer
lead-lag ratio errors. Different mixers can have differing
snuff-back characteristics.
Setting the Amount of
Setup
Snuff-back
NOTE: For Models 255179 and 255181 only
The MD2 valves with hard seats use two snuff-back
restrictor rings (13) to set the amount of snuff-back.
These two rings are trapped between the main valve
body and the nose piece. When the fluid valve pulls
back to close, it enters the restrictions, stops flow, and
pulls the fluid back until the needle reaches its carbide
seat.
Maximum snuff-back results when both restrictors are
used. Some snuff-back is still achieved without the
restrictors because of the pull-back action of the needles.
When dispensing wide mix ratios, it is best to use a
snuff-back restrictor only on the high volume side. This
keeps the high volume side from being pulled back into
the low volume side.
The MD2 valves with soft seats have an adjustable
snuff-back. Turn the knob on the back of the soft seat
MD2 valve to adjust the amount of snuff-back.
In general, use only as much snuff-back as necessary to
give a good cut-off of flow. Too much snuff-back pulls an
air bubble into the mixer. This can cause a drip, or cause
the mixer to spit when the valve is re-opened.
312185S 9
Page 10
Operation
Operation
Pressure Relief Procedure
1. Shut off the air to the supply pumps.
2. Close the bleed-type master air valve (required in
your system).
3. Hold a metal part of the valve firmly to the side of a
grounded metal pail, and trigger the dispense valve
to relieve pressure.
4. Shut off the air to the dispense valve, if applicable.
If you suspect that the dispense needle or hose is completely clogged, or that pressure has not been fully
relieved after following the steps above, very slowly
loosen the hose end coupling and relieve pressure gradually, then loosen completely. Now clear the needle or
hose.
• Apply and maintain air pressure to the ON (I) air
port on the valve, and remove air pressure from the
OFF (O) air port on the valve to open the valve.
• Apply and maintain air pressure to the OFF (O) air
port on the valve, and remove air pressure from the
ON (I) air port on the valve to close the valve.
Pneumatic Hand-held Valve
The valve operation is such that it is either fully open or
fully closed.
The valve is opened and closed by the internal air control valve. Trigger the gun to open the valve. Release the
trigger to close the valve.
Ratio Checking
The output mix ratio of your proportioner can be
checked by dispensing the two fluids separately out of
the nosepiece into tared cups. The cups can then be
weighed and the weights divided to get the mix ratio by
weight.
Lever Actuated Valve and Electric Switch Hand-held Valve
• Be sure the air supply lines are connected correctly
to the (I) and (O) valve air ports.
• To open or close the valve and maintain the open or
closed status, a minimum of 40 psi (280 kPa, 2.8
bar) air pressure must be supplied and maintained
at the (I) or (O) port.
• The trigger and lever only activates the electrical
switch in the handle, which turns the remote solenoid on and off. See page 20 for electrical diagram.
• Trigger the gun or pull the lever to turn the solenoid
on. Release the trigger or lever to turn the solenoid
off.
Machine Mount Valve
• Be sure the air supply lines are connected correctly
to the ON (I) and OFF (O) valve air ports.
• To open or close the valve and maintain the open or
closed status, a minimum of 40 psi (280 kPa, 2.8
bar) air pressure must be supplied and maintained
at the ON (I) or OFF (O) port.
Use ratio check nozzles 255247 with 15K688 retaining
nut for 1:1 models, or 255245 with 15K688 retaining nut
for 10:1 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.
10 312185S
Page 11
Maintenance
Daily Shutdown
When you are through using the MD2 valve, the outlet to
the mixer should be cleaned and protected from drying
or crystallization.
1. Remove and properly dispose of the static mixer.
2. Dispense a shot of material into a waste container
to clear any crossover in the nosepiece.
3. Wipe the nose with a clean rag being careful not to
let the materials contact each other.
Maintenance
4. Install the PTFE night cap (1:1 valves - 15K652,
10:1 valves - 15K628) and retaining nut (15K688).
Preventive Maintenance
There is a grease filled secondary seal/bearing area on
each valve shaft. Every 10,000 cycles, or twice each
month, new grease should be flushed across this area.
To grease the valve:
1. Remove the zerk grease fitting from each side of the
front or back of the valve.
2. Pump grease (115982) with grease gun (117792)
across the valve until clean grease comes out of the
other side.
3. Reinstall the zerk grease fitting.
312185S 11
Page 12
Troubleshooting
Troubleshooting
Problem Cause Solution
Valve does not open. Insufficient air pressure. Turn on air or increase air pressure.
Air not exhausted from the front side
of air cylinder piston.
Valve does not close and leaks. Insufficient air pressure. Turn on air or increase air pressure.
Air not exhausted from the back side
of air cylinder piston.
Blockage between needle and seat. Remove and clean needle and seat.
Damaged or missing gasket between
seat and housing (hard seat only).
Damaged or worn needle or seat. Replace both the needle and seat.
Too little snuff-back. Unscrew snuff-back adjustment nee-
Higher than normal back pressure. Nose piece is clogged. Remove and clean.
Mixer is curing. Replace mixer.
Soft spots in mixed material. Nose piece is clogged on one side. Remove and clean.
System is not properly balanced. Balance system with hoses, check
High static pressures build when
valve shuts off.
Low flow rate. Snuff-back rings (13) are installed
(hard seat only).
Use 4-way, relieving type air valve.
Use 4-way, relieving type air valve.
Replace gasket (38).
dle (25) 1/4 turn at a time.
valves, restrictors.
Turn off proportioner pump when
valve closes.
Remove snuff-back rings if they are
not required for maximum snuff-back.
12 312185S
Page 13
Repair
Repair
Disassembly
1. Relieve all air and fluid pressure, page 10.
2. Disconnect the valve from the system.
NOTE: In the following steps, keep the parts
from the A side and B side separate to prevent
cured material from forming on them.
3. Remove the two nosepiece screws (19), and pull the
nosepiece (29) away from the valve. Remove the
needle seats (27) and o-rings (20) for the 255179
and 255181 models. See F
4. 255179 and 255181 only: use a 5/32 in. socket
(4mm) to unscrew the needle (25). If the shaft (5)
spins, insert a dowel pin in the shaft hole to hold it
steady, then unscrew the needle. Slide the seal (26)
off the needle. Repeat for the other needle (25).
255180 and 255182 models: use a 3/32 pin punch
to remove the needle, then remove the seats (27)
and gaskets (28) from the inlet housing.
IG. 4.
5. Remove the two fluid housing screws (18) and
clamps (17) from the fluid housing (14). Slide the
fluid housing (14) off of the air cylinder (2). See F
5.
6. Remove the bearings (11), bearing o-rings (36, 13),
and secondary fluid seals (12, 15).
2
14
FIG. 5
16
13
36
15
11
12
17
18
IG.
TI9974A
20
26
27
25
19
F
IG. 4
312185S 13
29
14
TI9972A
Page 14
Repair
7. Remove the retaining ring (1) from the back of the
air cylinder (2). Push the two shafts (5) into the air
cylinder (2) to dislodge the air cylinder cap (22). See
F
IG. 6.
8. Push the two shafts (5) to dislodge the piston (9)
assembly from the air cylinder (2).
9. Use an o-ring pick to remove the o-rings (23) and
use a screwdriver to remove the sleeve bearings (7)
from the air cylinder (2).
10. Remove the o-rings (6) from the piston (9) and air
cylinder cap (22).
11. Remove the screw (24) and snuff-back adjustment
knob (21) from the cap (22). Use an o-ring pick to
remove the o-ring (23).
12. Remove the lock nuts (3), the pin (8), o-rings (4),
and piston o-ring (6) from the shaft (5).
210
FIG. 7
204
212
201
214
203
205
206
202
203
213
TI10408A
211
1
6
21
22
23
3
24
39
2
6
9
4
8
5
7
F
23
IG. 6
TI9975B
Pneumatic Handle (if equipped)
1. Remove the four screws (214). Pull the handle (205)
and gasket (204) away from the air cylinder (2).
2. Unscrew air valve plug (211) and remove spring
(213). Using a small diameter tool, push spool (202)
out from front. Inspect o-rings (203).
Electric Switch Handle (if equipped)
1. Disconnect the power from the gun.
2. The switch and cable are not repairable. Replace
these parts as a complete assembly. Use kit 255463
for series A handles. Use kit 24D049 for series B
handles.
3. Loosen the relief connector (112) and remove the
air valve plug (111).
4. Remove the wire which will take the electric
switch (114) and spacer (115) with it.
112
111
115
114
116
113
120
F
101
104
IG. 8
TI10384B
14 312185S
Page 15
Repair
Reassembly
Air Cylinder Section
1. Lubricate the shaft o-rings (23) and the bearings (7).
Insert o-rings into the air cylinder (2) and air cap
(22) cavities.See F
NOTE: The snuff-back adjustment knob (21),
shaft o-rings (23), and screw (24) are not present in models 255180, 255182, and 255183.
2. 255179 and 255182 only: Insert the snuff-back
adjustment knob (21) in the cap (22). Tighten the
screw (24) on the end of the snuff-back adjustment
knob (21). Torque to 25-30 in.-lb (2.8-3.4 N•m).
3. Press the bearings (7) flush into the air cylinder
housing (2) and air cap (22), trapping the o-rings
(23).
4. Lubricate and reassemble the piston assembly: piston (9), o-ring (6), dowel pin (8), nuts (3), o-ring (4),
and air cylinder shafts (5). Tighten nuts (3) to 25-30
in-lb (2.8-3.4 N•m). The shafts (5) should hang with
some play to be self-aligning in the bearing.
5. Lubricate the air cylinder (2) ID. Push the piston (9)
assembly into the air cylinder.
IG. 6.
6. 255179 and 255181, Insert the seals (26) with the
springs facing into the fluid housing (14).
7. With the “X” on the nosepiece on the same side as
the “MD2” on the air cylinder, install the nosepiece
(31) with the o-rings (20), seats (27), and nosepiece
screws (19). Tighten the nosepiece screws to
115-120 in-lb (14-15 N•m).
8. 255181 and 255182, Install injector tube (30) with
assembly tool (48). Torque to 168-192 in-lb
(19.0-21.7 N•m).
9. 255181 and 255182, Install injector tip (47) and
torque to 60-72 in-lb (6.8-8.1 N•m).
10. Remove zerk grease fitting (39). Fill grease in the
grease port below until grease begins to exit where
the zerk grease fitting (39) was located. Repeat for
the other zerk grease fitting (39). See F
IG. 6.
Pneumatic Handle (if equipped)
1. Liberally lubricate o-rings (203) and reassemble.
Install spool (202) and spring (213). Torque plug
(211) to 125-135 in-lb (14-15 N•m). See F
2. Align the gasket (204) and dispense valve on the
top of the handle (205). Torque the four screws
(214) evenly to 15-20 in-lb (1.7-2.2 N•m).
IG. 7.
6. Lubricate and assemble the o-ring (6) onto cap (22).
Push cap (22) into cylinder (2).
7. Install the outside retaining ring (1).
Fluid Section
1. Lubricate the bearings (11), o-rings (13, 36) and
seals (12, 15). Put the o-rings (13, 36) on the bearings. Carefully insert the seals (12) into the bearing
recess, with the lips of the seals facing into the bearing. Insert the seals (15) into the bearing with the
spring facing out of the housing. Be careful not to
damage the seal lips. See F
2. Push the bearings (11) into the air cylinder (2).
3. Grease the fluid housing (14) and install over the
bearings (11). Install the clamps (17) and screws
(18). Tighten to 25-30 in-lb (2.8-3.4 N•m).
4. For 255180 and 255182, insert the gaskets (28) and
seats (27).
5. Screw in the needle (25) and tighten it to 25-30 in.-lb
(2.8-3.4 N•m). See F
IG. 4.
IG. 5.
Electric Switch Handle (if equipped)
1. Install the plunger (113) and spring (116). See FIG.
8.
2. Insert the switch assembly (255463) while routing
the ground lug (108) through the hole in the top of
the handle.
3. Torque plug (111) to 125-135 in-lb (14-15 N•m).
4. Tighten the strain relief (112).
5. Install the ground screw (110) through the lock
washer (109) and ground lug (108). Torque to 15-20
in-lb (1.7-2.2 N•m).
6. Align the dispense valve on the top of the handle
(101). Torque the four screws (120) evenly to 15-20
lb (1.7-2.2 N•m).
312185S 15
Page 16
Parts
Parts
255179 and 255181
29
255181
47
30
18
16
2
1
17
11
12✖
13✖
36✖
15✖
19
2
29
14
20*†
26*
27*
25*
1
4❖✖
5✖
8
7❖
39
2
23❖
23❖
24
1
21
1
6
22
1
Torque to 25-30 in-lb (2.8-3.4 N•m).
2
Torque to115-120 in-lb (14-15 N•m).
6❖
3
1
TI21240A
9
16 312185S
Page 17
MD2 Valve
Parts
The parts listed below are common to all MD2 Dispense
valves. Parts which vary are found in the table at the bottom of this page.
Ref Part Description Qty
1 120762 RING, retainer 1
2 15K496 HOUSING, air cylinder 1
3 102920 NUT, lock 2
4❖✖ 157628 O-RING, buna-n 2
5✖ 15K421 SHAFT, primary 2
6❖ 156593 O-RING, buna-n 2
7❖ 551181 BEARING, sleeve 1/4, 3/8, 1/4,
nylon
8 551183 PIN, dowel 1/8 x 1.25 18-8 sst 1
9 626067 PISTON, air cylinder 1
11 15K422 BEARING, seal 2
12✖ 551191 PACKING, u-cup, nitrile 2
13✖ 113746 O-RING 2
14 15K441 HOUSING, inlet 2
15✖ 120768 SEAL, UHMWPE 2
16 15K442 SPACER, valve 2
17 15K444 CLAMP, adapter, inlet 2
18 121224 SCREW, cap, socket head, M5 x
0.8 x 8 mm
Ref Part Description Qty
19 107530 SCREW, cap, socket head, high
strength
20*† 117517 O-RING, fluoroelastomer 2
32 15K688 NUT, mixer; not shown 1
33 104765 PLUG, pipe, headless; not shown 2
36✖ 118594 O-RING, fluoroelastomer 2
38 551189 LUBRICANT, grease 3 oz. car-
tridge; not shown
39 120892 FITTING, grease 4
2
❖ Parts included in Valve Air Cylinder Repair Kit
255217 (purchase separately).
✖ Parts included in Valve Lube Seal Repair Kit 255218
(purchase separately).
* Parts included in Front Valve Repair Kit 255219 (pur-
chase separately).
† Parts included in Front Valve Repair Kit 255220 (pur-
chase separately).
2
2
1
Ref.
No. Description
21
KNOB, snuff-back, adjust
22a
CAP, air cylinder, snuff-back
❖23 O-RING, buna-n
24
STOP, snuff-back
25
NEEDLE, snuff-back *15K428 *15K428
26
SEAL, UHMWPE *120784 *120784
27
SEAT, needle *15K460 *15K460
29
HOUSING, nose
30
TUBE, injector, sst
31
CAP; not shown
40 ADAPTER, ratio check 255247 256794 1
47 TIP, injector 15V623 1
48 TOOL, assembly aid; not shown
1:1 10:1
15K419 15K419 1
15K420 15K420 1
156454 156454 3
15V627 15V627 1
15K445 15K649 1
15V624 1
15K652 15V628 2
256793 1
Qty255179 255181
2
2
2
312185S 17
Page 18
Parts
255180, 255182, and 255183
29
16
2
18
1
255182
25†
47
27†
30
2
26†
19
28†
20*†
39
29
17
12✖
11
13✖
36✖
15✖
14
4❖✖
5✖
8
7❖
2
23❖
1
6
22
1
Torque to 25-30 in-lb (2.8-3.4 N•m).
2
Torque to115-120 in-lb (14-15 N•m).
6❖
3
1
TI21241A
9
18 312185S
Page 19
MD2 Valve
Parts
The parts listed below are common to all MD2 Dispense
valves. Parts which vary are found in the table at the bottom of this page.
Ref Part Description Qty
19 107530 SCREW, high strength 2
20*† 117517 O-RING, fluoroelastomer 2
32 15K688 NUT, mixer; not shown 1
Ref Part Description Qty
1 120762 RING, retainer 1
2 15K496 HOUSING, air cylinder 1
3 102920 NUT, lock 2
4❖✖ 157628 O-RING, buna-n 2
5✖ 15K421 SHAFT, primary 2
33 104765 PLUG, pipe, headless; not shown 2
36✖ 118594 O-RING, fluoroelastomer 2
38 551189 LUBRICANT, grease 3 oz. car-
tridge; not shown
39 120892 FITTING, grease 4
42 299518 CAP, plug; not shown 2
6❖ 156593 O-RING, buna-n 2
7❖ 551181 BEARING, sleeve 1/4, 3/8, 1/4,
nylon
8 551183 PIN, dowel 1/8 x 1.25 18-8 sst 1
9 626067 PISTON, air cylinder 1
11 15K422 BEARING, seal 2
12✖ 551191 PACKING, u-cup, nitrile 2
13✖ 113746 O-RING 2
14 15K441 HOUSING, inlet 2
15✖ 120768 SEAL, UHMWPE 2
16 15K442 SPACER, valve 2
2
❖ Parts included in Valve Air Cylinder Repair Kit
255217 (purchase separately).
✖ Parts included in Valve Lube Seal Repair Kit 255218
(purchase separately).
* Parts included in Front Valve Repair Kit 255219 (pur-
chase separately).
† Parts included in Front Valve Repair Kit 255220 (pur-
chase separately).
17 15K444 CLAMP, adapter, inlet 2
18 121224 SCREW, cap, socket head, M5 x
2
0.8 x 8 mm
Ref.
No. Description
22
CAP, air cylinder
❖23 O-RING, buna-n
25
NEEDLE, snuff-back † 626062 † 626062 † 626062
26
SEAL, UHMWPE † 185467 † 185467 † 185467
27
SEAT, needle † 626060 † 626060
28
GASKET, seat † 171860 † 171860 † 171860
29
HOUSING, nose
30
TUBE, injector, sst
31
CAP; not shown
40 ADAPTER, ratio check 255247 255247 24P850 1
47 TIP, injector
48 TOOL, assembly aid 256793 1
1:1 1:1 10:1
15K447 15K447 15K447 1
156454 156454 156454 2
15K445 16T648 15K649 1
15V624 15V624 1
15K652 15K652 15V628 2
15V623 1
1
Qty255180 255183 255182
2
2
2
2
312185S 19
Page 20
Parts
Electric Switch Handle, 255208
NOTE: Extension cable 123660 is available.
1
105
106
1
120
113
116
114*
115*
111*
112*
2
119*
104
101
TI10384B
Series B handle shown
Ref Part Description Qty
101 15K666 HANDLE, 2K, dispense valve,
electric
104 15B209 TRIGGER, gun 1
105 192272 PIN, pivot 1
106 203953 SCREW, cap, hex hd, 10-24
UNC-3A x 3/8
111* PLUG, air valve 1
112* CONNECTOR, relief 1/4 npt 1
113 15K668 PLUNGER, trigger, 2K handle 1
114* SWITCH, elect mini snap action 1
115* SPACER, switch 1
116 551396 SPRING, 0.26X, 0.37X, 0.51 music
wire
119* CABLE, trigger, female, 3-pin con-
nector (Series A Handles Only)
CABLE, trigger, male, 4-pin con-
nector (Series B Handles Only)
120 117026 SCREW, cap, sch, M5 x 0.80 x
12 mm
* Parts included in Series A Handles Kit 255463 and
Series B Handles Kit 24D049 (purchase separately).
TI14761A
1
Torque to 25 in-lb (2.8 N•m).
2
Torque to 125-135 in-lb (14-15 N•m).
1
1
1
1
1
4
20 312185S
Page 21
Pneumatic Handle, 255206
204
4
210
214
203
202
2
203
213
2
211
3
215
Parts
216
3
207
205
212
206
1
201
3
TI21242A
Ref Part Description Qty
201 100721 PLUG, pipe 1
202 15B202 VALVE, spool 1
203* O-RING, chemically resistant fluorocarbon 3
204 15K661 GASKET, handle 1
205 15K658 HANDLE, 2K dispense valve, air 1
206 119626 PLUG, breather 1
207 192272 PIN, pivot 1
210 203953 SCREW, cap hex hd, 10-24 UNC-3A x 3/8 1
211 15B208 PLUG, air valve, 1/4 npt 1
212 15B209 TRIGGER, gun 1
213 117485 SPRING, compression 1
214 117026 SCREW, cap, sch, M5 x 0.80 x 12 mm 4
215 117509 COUPLER, line, air, 1/4 npt 1
216 117510 FITTING, line, air, 1/4 npt 1
1
Torque to 35 in-lb (4 N•m).
2
Apply lubricant on seals.
3
Apply thread sealant. Torque to 130 in-lb (15 N•m).
4
Torque to 25 in-lb (2.8 N•m).
* Parts included in Kit 246354 (purchase separately).
312185S 21
Page 22
Parts
Actuated Lever, 255249
305
1
319
310
307
308
302
303
301
304
306
1
309
303
Ref Part Description Qty
301 15K922 BLOCK, mounting lever, 2K 1
302 121191 BOLT, eye, 1/4-20 x 2 in. (51 mm) 1
303 100015 NUT, hex, 1/4-20 UNC 2-B 2
304 100016 WASHER, lock 1
305 192272 PIN, pivot 1
306 203953 SCREW, cap, hex, hd 1
307 551318 CONNECTOR, relief, 1/4 npt 1
308 121192 SWITCH, pushbutton 1
309 121193 PLUNGER, spring, 1/4-20 1
310 15M479 LEVER, actuator, valve 1
311 121194 SCREW, socket head cap, M5 - 0.8 x
30 mm (not shown)
319 123619 CABLE, trigger 1
1
Torque to 25 in-lb (2.8 N•m).
TI10410B
4
22 312185S
Page 23
Accessories
Plastic Tube Fittings to Connect Air Signals
Tube OD 1/8 NPT (M) Straight 1/8 NPT (M) 90° Swivel
Accessories
5/32 in.
1/4 in.
Tube OD 1/4 NPT (M) Straight 1/4 NPT (M) 90° Swivel
5/32 in.
1/4 in.
114263
115671
598252
104165
114151
112698
114469
114109
Inlet Check Valves (3000 psi working pressure)
Part No. Size Description
501867
501684
949709
949710
1/4 NPT (M x M)
3/8 NPT (M x M)
3/8 NPT (M x M)
3/8 NPT (M x M)
303 sst with PTFE o-ring poppet (2 psi crack pressure).
303 sst with PTFE o-ring poppet (2 psi crack pressure).
Carbon steel carbide seat (50 psi crack pressure).
Carbon steel carbide seat (100 psi crack pressure).
Catalyst Injectors
Catalyst injectors are restrictive check valves which are often used to create back pressure on the catalyst side inlet
to the MD2 valve. Catalyst injectors are also used to balance pressures and flow on wide-ratio, low-viscosity catalyst
applications.
Typical
Injector No. Size Code Bore Dia. Needle Dia.
Application
Viscosity
Typical Used
Sealant*
948291 #125 0.125 in. 0.086 in. 500-50,000 cps Polysulfide
948258 #35 0.110 in. 0.086 in. 1000-10,000 cps Silicone
947937 #40 0.098 in. 0.086 in. 200-1,500 cps Urethane
570251 #42 0.0935 in. 0.086 in. 50-800 cps Urethane
* Wide ratio applications 8:1 to 13:1 by volume.
** Injectors have a “snout” and must be screwed into a 1/4 npt(f) female coupling. Inlet is 1/4 npt(f).
312185S 23
Page 24
Accessories
Plastic Tubing for Air Signal Lines
Part No. Description
514607 5/32 in. O.D. Nylon
C12509 1/4 in. O.D. Nylon
Mixers and Shroud
ID x # elements 50 pack 250 pack Shroud
3/16 x 32 LC0077 LC0084 LC0063
1/4 x 24 LC0078 LC0085 LC0057
3/8 x 24 LC0079 LC0086 LC0058
3/8 x 36 LC0080 LC0087 LC0059
3/8 Combo LC0081 LC0088 LC0060
3/16 x 32 Luer Lock LC0082 LC0089 LC0061
1/4 x 24 Luer Lock LC0083 LC0090 LC0062
Nose Piece Accessories
Part No. Description Notes
15K652 1:1 nightcap PTFE cap to protect the 1:1 outlet when not in use
15V628 10:1 nightcap PTFE cap to protect the 10:1 outlet when not in use
255247 1:1 ratio check nozzle Splits the flow on 1:1 valves to facilitate ratio checks
24P850 10:1 ratio check nozzle Splits the flow on 10:1 valves to facilitate ratio checks
258687 10:1 check tip Assembly for low volume side material that is very thin
256793 Tool Assembly tool to aid in the installation and removal of
injector tube 15V623
15K688 7/8-9 retaining nut Use to hold 15K652, 255247 and 255245 on to valve
24 312185S
Page 25
Accessories
Orifice Kits
In the following table, shaded rows indicate “Super Standard” items that are typically stocked and provide the best
delivery dates.
Impingement
Port Size
Kit Type and Kit Number
250 Model Polyol
Orifice Kit
250 Model Iso
Orifice Kitin. mm
0.016 0.41 24C805 24D229
0.020 0.51 24C751 24D223
0.024 0.61 24C806 24D230
0.028 0.71 24C807 24D231
0.031 0.79 24C752 24D224
0.035 0.89 24C808 24D232
0.039 0.99 24C809 24D233
0.042 1.07 24C810 24D234
Impingement
Port Size
0.047 1.19 24C753 24D225
0.052 1.32 24C811 24D235
0.055 1.40 24C812 24D236
0.060 1.52 24C754 24D226
0.063 1.60 24C813 24D237
0.067 1.70 24C755 24D227
0.073 1.85 24C815 24D238
0.086 2.18 24C756 24D228
Kit Type and Kit Number
250 Model Polyol
Orifice Kit
250 Model Iso
Orifice Kitin. mm
Orifice Kit
504
503
502
501
505
4
3
507
3
506
3
509
Ref. Part Description Qty.
501 --- HOUSING, orifice 1
502†‡ --- O-RING, 0.63 in. diameter 1
503† --- O-RING, 0.44 in. diameter 1
504†◆ --- O-RING, 0.37 in. diameter 1
505 --- STEM, valve 1
506† --- RING, backup, PTFE 1
507† --- O-RING, 0.28 in. diameter 1
509 --- CAP, orifice 1
510 --- TOOL, cleanout; #78 drill bit (not
shown)
1
ti21829a2
3
Apply a light coating of lubricant to seals and surfaces
specified.
4
Fasten stem (505) into housing (501). Fasten
cap (509) onto housing (501) and torque to 60-70 in-lb
(6.8-7.9 N•m). Unscrew stem (505) until it bottoms out
against cap (509).
† Parts included in kit 24D321.
‡ Parts included in kit 248130 (pack of 6).
◆ Part included in kit 248128 (pack of 6).
312185S 25
Page 26
Accessories
24E505 Orifice Block Kit
401
Part 122737, Swivel Adapter - JIC 6 x 1/4 npt,
not included in kit
Part 122961, Swivel Adapter - JIC 5 x 1/4 npt,
not included in kit
402b
MD2 Valve not included
401d
1
Lubricate all o-rings and specified surfaces.
2
Torque to 20-30 in-lb (2.2-3.4 N•m).
Ref. Part Description Qty.
401 HOUSING, orifice, assy;
includes 401a-401d
401a HOUSING, orifice 1
401b WASHER 1
401c NUT 1
401d 123886 O-RING 1
402 KIT, orifice block plug; includes
402a and 402b
402a PLUG, orifice 1
402b 117724 O-RING 1
24E505 does not include an MD2 valve. See MD2
Valve Models on page 2.
402a
1
2
401b
401c
401a
ti21829a1
1
1
24E505 does not include swivel adapters. Swivel
adapters 122961 and 122737 must be purchased
separately.
See manual 3A0861 for ratio check assembly
24F227.
26 312185S
Page 27
Valve Accessories
Accessories
551351 Short Throw Spacer
A spacer under the air piston that limits how far the fluid
needles push open. It reduces the amount of material
surge when the valve opens, and reduces the amount of
snuff-back available. Used for dispensing low flow small
diameter beads. For 255180 and 255182 only.
123660 Extension Cable, 6.0 m (19.7 ft)
For locating the valve further from the base system than
allowed with the original cable provided. For use with the
electric handle 255208 and actuated lever 255249.
Conversion Kits
Part No. Description Notes
255206 Pneumatic Handle Convert any valve to a hand held valve with an internal
pneumatic 4-way valve. See page 21.
255208 Electric Handle Convert any valve to a hand held valve with an internal nor-
mally open switch. See page 20.
255249 Electric Lever Switch Convert any valve to a hanging valve with an internal nor-
mally open switch. See page 22.
255273 Hanger Adapter Add to any hand held valve to allow it to be hung.
123902 Cable Replaces trigger cable included with electric handle 255208
and actuated lever 255249. For converting handle/lever to
connect to systems previously connected to a TwinMixer
gun. Use pins 1 (brown) and 3 (blue).
®
Hanger Adapter
255273
TI10512A
312185S 27
Page 28
Accessories
Front Valve Repair Kits
Part No. Description
255219 Repair Kit for adjustable
snuff-back valves 255179 and
255181 only.
255220 Repair Kit for non-adjustable
snuff-back valves 255180,
255182, and 255183 only.
G 1/2 Outlet Kit
Part No. Description
16T802 Adapter to allow for the mounting
of G 1/2 threaded mixers. Applicable for 10:1 MD2 valves only.
Angled Adapter Kits
24W045 - 25° angle
24W046 - 15° angle
24W047 - 5° angle
Ref. Part Description Qty.
601 17B515 25° adapter block 1
17B516 15° adapter block 1
17B517 5° adapter block 1
602 15K661 GASKET, handle 2
603 117026 SCREW, socket head, M5x12 8
602
603
601
602
o
x
r_16t802
28 312185S
Page 29
Technical Data
Technical Data
Maximum Fluid Pressure 255179-255182: 3000 psi (20.7 MPa, 207 bar)
255183: 2000 psi (13.8 MPa, 138 bar)
Maximum Cylinder Air Pressure 120 psi (0.84 MPa, 8.4 bar)
Air Inlets (open (I) and close (O) ports) 1/8 npt(f)
Fluid Inlets 9/16 straight thread o-ring boss “A” and “B”
Fluid Outlet 7/8-9 bell outlet
Fluid Viscosity Range
Soft Seats 1-1 million cps
Hard Seats 20-1 million cps
Fluid Section Sealing Isolation chamber with zerk fittings and dual seals.
Divorced Air Cylinder Double acting, buna-n o-rings
Weight
255179 / 255180 (1:1 valves) 1.45 lb (0.66 kg)
255181 / 255182 (10:1 valves) 1.50 lb (0.68 kg)
255206 (pneumatic handle) 0.85 lb (0.39 kg)
255208 (electric handle) 0.90 lb (0.41 kg)
255249 (electric lever) 0.75 lb (0.34 kg)
Wetted Parts
Stainless Steel Valve 303 sst, 17-4 SS, UHMWPE, PEEK, Chemical Resistant
o-rings. 440C SS and C2 carbide with cobalt binder (hard
seat only)
Dimensions
6.64 in. (168.7 mm)
5.64 in. (143.3 mm)
0.28 in. (7.1 mm)
M5 x 0.8 mounting holes (2)
4.29 in. (109 mm)
1.06 in. (26.9 mm)
M5 x 0.8 mounting
holes (4)
0.73 in. (18.5 mm)
0.73 in. (18.5 mm)
4.60 in. (116.8 mm)
TI9977A
312185S 29
TI10654A
Page 30
Graco Standard Warranty
Graco warrants all equipment referenced in this document which is manufactured by Graco and bearing its name to be free from defects in
material and workmanship on the date of sale to the original purchaser for use. With the exception of any special, extended, or limited warranty
published by Graco, Graco will, for a period of twelve months from the date of sale, repair or replace any part of the equipment determined by
Graco to be defective. This warranty applies only when the equipment is installed, operated and maintained in accordance with Graco’s written
recommendations.
This warranty does not cover, and Graco shall not be liable for general wear and tear, or any malfunction, damage or wear caused by faulty
installation, misapplication, abrasion, corrosion, inadequate or improper maintenance, negligence, accident, tampering, or substitution of
non-Graco component parts. Nor shall Graco be liable for malfunction, damage or wear caused by the incompatibility of Graco equipment with
structures, accessories, equipment or materials not supplied by Graco, or the improper design, manufacture, installation, operation or
maintenance of structures, accessories, equipment or materials not supplied by Graco.
This warranty is conditioned upon the prepaid return of the equipment claimed to be defective to an authorized Graco distributor for verification of
the claimed defect. If the claimed defect is verified, Graco will repair or replace free of charge any defective par ts. The equipment will be returned
to the original purchaser transportation prepaid. If inspection of the equipment does not disclose any defect in material or workmanship, repairs will
be made at a reasonable charge, which charges may include the costs of parts, labor, and transportation.
THIS WARRANTY IS EXCLUSIVE, AND IS IN LIEU OF ANY OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
TO WARRANTY OF MERCHANTABILITY OR WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE.
Graco’s sole obligation and buyer’s sole remedy for any breach of warranty shall be as set forth above. The buyer agrees that no other remedy
(including, but not limited to, incidental or consequential damages for lost profits, lost sales, injury to person or property, or any other incidental or
consequential loss) shall be available. Any action for breach of warranty must be brought within two (2) years of the date of sale.
GRACO MAKES NO WARRANTY, AND DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE, IN CONNECTION WITH ACCESSORIES, EQUIPMENT, MATERIALS OR COMPONENTS SOLD BUT NOT
MANUFACTURED BY GRACO. These items sold, but not manufactured by Graco (such as electric motors, switches, hose, etc.), are subject to
the warranty, if any, of their manufacturer. Graco will provide purchaser with reasonable assistance in making any claim for breach of these
warranties.
In no event will Graco be liable for indirect, incidental, special or consequential damages resulting from Graco supplying equipment hereunder, or
the furnishing, performance, or use of any products or other goods sold hereto, whether due to a breach of contract, breach of warranty, the
negligence of Graco, or otherwise.
FOR GRACO CANADA CUSTOMERS
The Parties acknowledge that they have required that the present document, as well as all documents, notices and legal proceedings entered into,
given or instituted pursuant hereto or relating directly or indirectly hereto, be drawn up in English. Les parties reconnaissent avoir convenu que la
rédaction du présente document sera en Anglais, ainsi que tous documents, avis et procédures judiciaires exécutés, donnés ou intentés, à la suite
de ou en rapport, directement ou indirectement, avec les procédures concernées.
Graco Information
For the latest information about Graco products, visit www.graco.com.
TO PLACE AN ORDER, contact your Graco distributor or call to identify the nearest distributor.
Phone: 612-623-6921 or Toll Free: 1-800-328-0211 Fax: 612-378-3505
All written and visual data contained in this document reflects the latest product information available at the time of publication.
GRACO INC. AND SUBSIDIARIES • P.O. BOX 1441 • MINNEAPOLIS MN 55440-1441 • USA
Copyright 2007, Graco Inc. All Graco manufacturing locations are registered to ISO 9001.
Graco reserves the right to make changes at any time without notice.
For patent information, see www.graco.com/patents.
Original instructions. This manual contains English. MM 312185
Graco Headquarters: Minneapolis
International Offices: Belgium, China, Japan, Korea
www.graco.com
Revised June 2014
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