Graco 306640E User Manual
INSTRUCTIONS–PARTS
This
manual contains important
warnings and information.
READ AND KEEP FOR REFERENCE.
INSTRUCTIONS
LIST
First
choice when
quality counts.
306–640
Supersedes D
Rev
. E
Back
Pressure V
alve
300 psi (21 bar, 2.1 MPa) Maximum Inbound Pressure
180 psi (12.4 bar, 1.24 MPa) Maximum Regulated Pressure
Model 205–122, Series C
Equipment
This equipment is for professional use only
Read all instruction manuals, tags, and labels before operating the equipment.
Use the equipment only for its intended purpose. If you are uncertain about usage, call your Graco
distributor.
Do not alter or modify this equipment. Use only genuine Graco parts and accessories.
Check equipment daily
misuse can cause the equipment to rupture or malfunction and result in serious injury
.
. Repair or replace worn or damaged parts immediately
.
.
Do not exceed the maximum working pressure of the lowest rated component in your system. This
equipment has a 300 psi (21 bar, 2.1 MPa) maximum inbound pressure and a 180 psi (12.4 bar
1.24 MPa) maximum regulated pressure.
Use fluids and solvents which are compatible with the equipment wetted parts. Refer to the
nical Data
Comply with all applicable local, state, and national fire, electrical, and safety regulations.
section of all equipment manuals. Read the fluid and solvent manufacturer’s warnings.
PRESSURIZED EQUIPMENT HAZARD
Spray
from the gun, hose leaks, or ruptured components can splash fluid in the eyes or on the skin
and cause serious injury
Do not stop or deflect leaks with your hand, body
T
ighten all fluid connections before operating the equipment.
Follow the
sure; stop spraying; clean, check, or service the equipment; and install or clean the spray nozzle.
Pressure Relief Procedure
GRACO INC. P.O. BOX 1441
.
COPYRIGHT
Graco
Inc. is registered to I.S. EN ISO 9001
, glove or rag.
on page 2 whenever you: are instructed to relieve pres
MINNEAPOLIS, MN
1994, GRACO INC.
55440–1441
,
Tech-
-
Pressure Relief Procedure.
WARNING
PRESSURIZED
The
system pressure must be manually relieved to
prevent the system from starting or spraying accidentally
o reduce the risk of an injury from accidental spray from
T
the gun, splashing fluid, or moving parts, follow the
Pressure Relief Procedure
are instructed to relieve the pressure,
stop spraying,
check or service any of the system equipment,
or install or clean the spray nozzle.
1.
Shut of
f the power to the pump. If you are using an air–
powered pump, open the bleed–type master air valve.
2. T
rigger the gun.
3.
Relieve the line pressure by turning the adjusting screw
(26) counterclockwise until there is no spring pressure.
EQUIPMENT HAZARD
.
whenever you:
Installation
This valve is used in a circulating system to regulate the back
pressure to spray guns and to maintain the proper circulating
pressure throughout the system.
22
Fig. 2
11
04520
Operation
The
back–pressure valve controls pressure in the fluid
return–line. Adjust the pump pressure and the back–pressure
valve for the best combination of spraying pressure and fluid
circulation.
o adjust the back–pressure valve, loosen the locknut (27)
T
and insert the hex key wrench (7) into the socket on the
adjusting screw (26). T
pressure in the return line. T
to decrease
ment by tightening the locknut (27).
pressure in the return line. Lock in the adjust
urn the screw
urn the screw counterclockwise
clockwise to increase
-
The valve is adjustable to control fluid pressure in a circulat
ing system from 0 to 180 psi (0 to 12.4 bar
, 0 to 1.24 MPa).
CAUTION
T
o prevent damage to the diaphragm, the hard carbide seat
and stem, and other sensitive parts, handle the valve care
fully.
Install the valve in the return line of the spray guns, down
stream from the last gun. See Fig. 1. Connect the return line
to the 3/8 npsm(m) inlet (22) and the 3/8 npsm(f) outlet (1
Be sure the connections match the direction of fluid flow in
the line. See Fig. 2.
B
A
-
1).
C
D
E
-
-
NOTE: Always check and adjust the back pressure valve if
you make changes to the system such as a change of fluids,
the length of the lines, and the number of spray guns.
Flush the valve with a compatible solvent whenever the rest
of the system is being flushed. Fully open the valve before
flushing by turning the adjustment screw counterclockwise.
Always use the lowest possible pressure when flushing.
Service
NOTE:
good working condition. Refer to the Parts drawing on page
3.
1.
2.
3. Unscrew the cap
4.
5.
F
Clean and check the valve regularly to maintain it in
Remove the valve from the system.
Disassemble the pressure gauge (5) and the tube (16)
from the inlet adapter (22). Remove the inlet adapter and
the outlet union (1
adjusting screw (26) and the locknut (27).
Remove the spring plate (15) and the spring (13).
Loosen the cap nut (4). Disassemble the diaphragm and
its related parts (2,10, 18, 19, 20, 21).
1) from the housing (25).
(28) from the housing (25). Remove the
Fig.
1
CAUTION
04521
Be careful not to damage the valve seat (1) or stem (2)
which are made of hard carbide.
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