Graco GM 3500 Instructions-Parts List Manual page 17

USE EXTREME CAUTION WHEN PERFORMING THIS CALIBRATION 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 2600–3000 psi
(182–210 bar) MAXIMUM WORKING PRESSURE.
Perform this procedure whenever the pressure con-
trol assembly is removed and reinstalled, or replaced,
to be sure the sprayer is properly calibrated.
Improper calibration 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.
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
NEW spray tip, size 0.025 to 0.029
3/8 in. ignition wrench or nut driver
5 gallon pail of water or mineral spirits
Swivel, 156–823
Nipple, 162–453
Tee, 104–984
Set Up
1. Follow the Pressure Relief Procedure Warning on
page 13.
2. Set up the system as shown in Fig 17–1.
Set the Dead Band (Pressure Differential)
NOTE: Do not alter this adjustment if the wheel is already
set as shown in Fig 17–2.
1. Remove the pressure control cover.
2. Set the white differential wheel (A) on the micros-
witch. Turn the wheel so the letter F is concealed be-
hind the switch and the letter A is the first letter seen.
Pressure Up
1. Start the sprayer and prime it.
2. Adjust the pressure to 2600 psi (180 bar).
3. Shut off the engine. If the pressure drops, replace the
pump packings before proceeding. See page 18.
Adjust the Pressure See Fig 17–3
1. Remove the plug (320) in the bottom of the pressure
control.
2. Turn and hold the pressure control knob (B) at the
maximum pressure setting.
3. Engage the nut (C): insert the nut driver through the
pressure control hole or use the ignition wrench from
the front of the presure control.
a. Loosen the nut just until you hear a click. Stop.
b. Slowly tighten the nut just until another click is
heard. Stop.
4. Replace the plug (320) and pressure control cover.
PRESSURE CONTROL CALIBRATION
WARNING
NEVER attempt to increase the fluid outlet pressure
by performing these calibrations in any other way.
NEVER EXCEED 3000 PSI (210 BAR) MAXIMUM
WORKING PRESSURE. Normal operation of the
sprayer at higher pressures could result in component
rupture, fire or explosion.
ALWAYS use a new 50 foot (15.2 m) spray hose, rated
for at least 3000 PSI (210 BAR) MAXIMUM WORK-
ING PRESSURE, when performing this procedure. A
used, under–rated hose could develop a high pres-
sure leak or rupture.
Fig 17–1
INSIDE PRESSURE CONTROL LOOKING UP
AT BOTTOM OF DIFFERENTIAL WHEEL
Fig 17–2
A
Fig 17–3
102–814
PRESSURE GAUGE
156–823
SWIVEL
104–984
TEE
162–453
NIPPLE
223–541
HOSE
A
B
C
320