Pressure Control Adjustment - Graco EM 390 Instructions And Parts List

USE EXTREME CAUTION WHEN PERFORMING THIS ADJUSTMENT PROCEDURE to reduce the risk of a
fluid injection injury or other serious bodily injury, which can result from component rupture, electric shock, fire,
explosion or moving parts.
This procedure sets the sprayer to 2500 psi (172 bar)
MAXIMUM WORKING PRESSURE.
Perform this procedure whenever the microswitch or
pressure control assembly is reinstalled or replaced,
to be sure the sprayer is properly calibrated.
Improper adjustment can cause the sprayer to over–
pressurize and result in component rupture, fire or ex-
plosion. It may also prevent the sprayer from obtaining
the maximum working pressure, resulting in poor
sprayer performance.
Pressure Relief Procedure
To reduce the risk of serious bodily injury, including fluid
injection, splashing in the eyes or on the skin, or injury
from moving parts, always follow this procedure when
you shut off the sprayer, when checking, adjusting or
cleaning the system, and when changing spray tips.
1. Engage the gun safety latch.
2. Turn the ON/OFF switch to OFF.
3. Unplug the power supply cord.
Service Tools Needed:
NEW 50 foot (15.2 m), 3000 psi (210 bar), flexible
nylon, airless spray hose, Part No. 223–541
0–5000 psi (0–350 bar) fluid–filled pressure gauge,
Part No. 102–814
Needle valve, Part No. 102–715 or 103–067
3/8 in. socket wrench
5 gallon pail and water
Mineral spirits

PRESSURE CONTROL ADJUSTMENT

WARNING
WARNING
NEVER attempt to increase the fluid outlet pressure
by performing these adjustments in any other way.
Normal operation of the sprayer at higher pressures
could result in component rupture, fire or explosion. To
perform this adjustment, however, the sprayer pres-
sure must be temporarily increased above the normal
working pressure.
Use a new 50 foot (15.2 m) spray hose, rated for at
least 3000 psi (210 bar) MAXIMUM WORKING
PRESSURE, when performing this procedure. A
used, under–rated hose could develop a high pres-
sure leak or rupture.
4. Disengage the gun safety latch. Hold a metal part
of the gun firmly to the side of a grounded metal
pail, and trigger the gun.
5. Engage the gun safety latch.
6. Open the fluid pressure drain valve and leave it
open until you start the sprayer again.
If you suspect the hose or spray tip is completely
clogged or that pressure is not fully relieved after fol -
lowing the steps above, VERY SLOWLY loosen the tip
guard retaining nut or hose end coupling and relieve
pressure gradually. Now loosen the part completely.
Clear the tip or hose obstruction.
1. Follow the Pressure Relief Procedure Warning,
above.
2. Connect the new 50 ft. (15.2 m) spray hose to the
sprayer outlet. Install the needle valve on the other
end of the hose. Install the fluid–filled pressure gauge
in the top port of the fluid filter.
3. Remove the pressure control cover (41) and the plug
(121) ( see the parts drawings) from the bottom of the
pressure control. In Step 6, you will insert the 3/8 in.
socket wrench through the plug hole (C) to engage
the pressure adjustment nut (B) which is located on
the bottom of the pressure control knob shaft. See Fig
25–1.