Section 8
MAINTENANCE
31
Figure 8-8 Pressure Switch (P/N 040694)
tacts do not open or they open prior to the desired
pressure, the pressure switch setting will require ad-
justment.
FOR PRESSURE RANGE ADJUSTMENT:
1. Remove cover to pressure switch.
2. Turn the range adjusting screw to the high pres-
sure setting. Turning the screw counterclockwise
lowers both the high and low pressure equally.
FOR DIFFERENTIAL ADJUSTMENT:
Differential is the difference between the high and
low pressure settings. 10 psig (0.7 bar) is typical.
1. Turn the differential adjusting screw to the lower
(reset) setting. Turning the screw counterclock-
wise widens the differential by lowering the reset
(lower) setting only.
2. When the pressure switch adjustment is com-
plete, the pressure regulator should be adjusted
for the pressure at which modulation of air deliv-
ery should begin. In this case that pressure will
be 103 psig (7.1 bar). The regulator is adjusted
by loosening the jam nut on the end of the cone
shaped cover of the pressure regulator. When
the jam nut is loose, turn the adjusting screw
clockwise to increase or counterclockwise to de-
crease the setting.
3. To set the regulator, continue closing the service
valve, until the line pressure is 103 psig (7.1 bar).
At this point regulator should pass a signal to the
inlet valve to start closing it. If the line pressure
keeps on rising or if the modulation does not be-
gin, adjust the regulator valve as described
above. After adjustment line pressure should be
approximately 103 psig (7.1 bar) and 1.00 in. Hg
vacuum below the inlet.
4. Now close the service valve, line pressure will
start rising. When line pressure reaches 110
psig. (7.6 bar), the inlet valve will be closed to its
maximum position. The inlet vacuum at this point
will be around 25 in. Hg. The machine should un-
load at this point.
5. Open the service valve so the line pressure is 100
psig (6.9 bar). Machine is now set for operation.
Recheck the unload pressure by closing of the
service valve. Machine should unload via the
pressure switch at 110 psig (7.6
bar).
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