Graco 3A0427B Thermostat User Manual


 
Operation
3A0427B 7
Operation
Pressure Relief Procedure
1. Shut off the fluid supply.
2. Leave on the air to the fluid regulator.
3. Trigger the gun to relieve the fluid pressure.
4. Shut off the air supply to the fluid regulator.
5. Open the fluid drain valve to relieve all fluid pres-
sure, having a container ready to catch the drain-
age.
Available Pressures
This fluid regulator provides accurate, positive fluid
pressure control to a spray gun or other device. The reg-
ulated fluid outlet pressure is proportional to the pilot air
signal supplied to either the high or low air inlet port.
Each port can be controlled independently.
All three models have the high pressure port, which is
fixed at 1:1. Ratios of 1:1, 1:2, and 1:3 are available for
low pressure applications. The ratio spacer (3, F
IG
. 2) is
color coded to indicate ratio:
Silver (1:1 ratio)
Green (1:2 ratio)
Black (1:3 ratio)
See the Performance Data on pages 16 and 17 to help
determine which ratio is best for your application. Per-
formance is affected by:
Fluid inlet pressure
Fluid viscosity
Size (ID) and length of the regulated fluid outlet line
Size (ID) and length of the fluid inlet supply line.
High Port Operation
Use the high port for:
commanding a higher pressure for faster flushing
higher fluid viscosities
To operate, shut off the air to the low pressure inlet and
turn on the air to the high pressure inlet.
Low Port Operation
Use the low port for:
precise control in critical applications
lower fluid viscosities
To operate, shut off the air to the high pressure inlet and
turn on the air to the low pressure inlet.
Adjust the Fluid Regulator
The fluid regulator controls pressure downstream from
its outlet. Set the inlet fluid pressure at least 10 psi (.07
MPa, 0.7 bar) higher than the regulated outlet fluid pres-
sure.
Apply a pilot air signal to either the high or low port. The
minimum air pressure depends on the ratio. See the
Performance Data on pages 16 and 17.
If using an accessory fluid pressure gauge, trigger the
air spray gun to relieve pressure in the line when reduc-
ing the pressure, to ensure a correct gauge reading.
Flushing
Flush before changing colors, at the end of the day,
before storing, and before repairing the equipment.
Flush with a fluid that is compatible with the fluid you
are pumping and with the wetted parts of your sys-
tem. Check with your fluid manufacturer or supplier
for recommended flushing fluids and flushing fre-
quency. Relieve the pressure after flushing.
Do not allow paint or solvent to sit in the system for
extended periods.