Control System Adjustment; For Pressure Range Adjustment; For Differential Adjustment - Sullair LS-200 Operator's Manual And Parts List

Section 8
MAINTENANCE
Figure 8-5 Pressure Switch (P/N 040694)
3. Remove used filter assembly, and replace with
new assembly.
4. Coat/lubricate the o-rings will silicone grease.
5. Reattach the connectors to the sight glass/orifice
blocks.

CONTROL SYSTEM ADJUSTMENT

Refer to Figure 8-5. Prior to adjusting the Control
System, it is necessary to determine the desired
operating pressure range and also the maximum
pressure at which your compressor is to operate.
The pressure must not exceed the maximum oper-
ating pressure which is stamped on the compressor
serial number nameplate. The following explanation
applies to a typical installation with a desired
operating range of 100 to 110 psig (6.9 to 7.6 bar).
This information will apply to a compressor with any
other operating range excepting the stated pres-
sures.
Remove the cover of the pressure switch. With the
shut-off valve closed (or slightly cracked open)
start the compressor. Observe the line pressure
gauge and pressure switch contacts. When the line
pressure reaches 110 psig (7.6 bar), the pressure
switch contacts should open. If the pressure switch
contacts do not open or they open prior to the
desired pressure, the pressure switch setting will
require adjustment (refer to Figure 8-5).

FOR PRESSURE RANGE ADJUSTMENT:

1. Remove cover to pressure switch.
2. Turn the range adjusting screw to the high pres-
52
sure setting. Turning the screw counterclock-
wise 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 102 psig (7.0 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
decrease the setting.
3. To set the regulator, continue closing the service
valve until the line pressure is 102 psig (7.0 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
begin, adjust the regulator as described above.
After adjustment, line pressure should be
approximately 102 psig (7.0 bar) and 1.00 in. Hg
(2.54 cm Hg.) vacuum below the inlet.
4. Next, 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 (63.5 cm Hg.). The
machine should unload at this point.
5. Open the service valve so the line pressure is
100 psig (6.9 bar). Machine is now set for oper-
ation. Recheck the unload pressure by closing
of the service valve. Machine should unload via
the pressure switch at 110 psig (7.6 bar).
After the control pressures have been adjusted, the
"unloaded" sump pressure should be checked. It
will be necessary to shut the compressor down,
remove the pressure switch cover, and disconnect
one of the two lead wires that are connected to the
micro-switch (contact block). In order to have a cor-
rect reading, the air system to which the compres-
sor is connected must be pressurized to at least 80
psig (5.5 bar). After disconnecting the lead, tape the
exposed wire with electrician's tape to make sure
that it does not come in contact with any metallic
surface.