Graco 238890, 238892, 238894 Operation, Adjusting the System Pressure, Cleaning the Regulator

Operation

Adjusting the System Pressure

CAUTION

DThe new system must be cleaned and tested thoroughly before admitting fluid to the regulator to avoid contaminants clogging or damaging the regulator.

DAlways use the lowest possible air and fluid pressures for your application. High pressures can cause premature spray tip, regulator, and pump wear.

NOTES:

DThe fluid pressure regulator controls pressure downstream from its outlet.

DIf you are using an accessory fluid pressure gauge (H in Fig. 1), relieve the spray gun line pressure after you reduce the regulator pressure to ensure a correct gauge reading.

1.Make a note of the proper way to adjust pressure, from the following descriptions:

D On a spring-operated regulator, turn the adjusting screw (10) counterclockwise to decrease pressure and clockwise to increase pressure to the spray gun or extruder gun.

D On an air-operated regulator, increase supply air pressure to increase fluid pressure. Decrease supply air pressure to decrease fluid pressure. Supply air up to 100 psi (0.7 MPa,

7 bar). See the chart on page 20 for air versus fluid pressure.

NOTE: Air-operated regulator Models 238893 and 238894 are provided with an air supply regulator (31) to control the fluid set pressure. For increased sensitivity in pressure set point performance, an alternative air regulator, such as Part 206197, may be used. This alternative air regulator uses a sensitive diaphragm design to maintain a higher, more accurate air pressure setting.

2.Adjust the pump air pressure and fluid regulator for the desired spray pattern. Use the lowest possible air and fluid pressures for your application. For optimum performance, the inbound fluid pressure should be at least 500 psi (3.4 MPa, 34 bar) above the regulated fluid pressure.

NOTE: Do not exceed a 2000 psi (14 MPa,

138 bar) pressure drop between the regulator inlet and outlet. Excessive pressure drop will cause premature regulator component wear.

For example: With 3500 psi (24.5 MPa, 245 bar) to the regulator, the minimum regulated outlet pressure would be 1500 psi (10.5 MPa, 105 bar).

3.In a circulating system, also adjust the back pressure valve (K).

4.Record all the settings for future reference.

Cleaning the Regulator

Do not allow fluid to settle in the system.

Flush the regulator whenever the rest of the system is flushed (see page 9). Before you flush the system, follow the Pressure Relief Procedure on page 7, then completely decrease the regulated fluid pressure. See step 1 in Adjusting the System Pressure, at left.

Before you remove the regulator for thorough cleaning and inspection, follow the Pressure Relief Procedure on page 7. Then remove the regulator, clean it, and inspect all parts.

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