Sullair 1800 User Manual page 18

1800-3000 USER MANUAL
Full Load Mode
—50 to 100 PSIG (3.4 to 6.9 BAR)
When the compressed air pressure rises above 50
psig (3.4 bar), the minimum pressure valve opens
allowing compressed air to flow into the service line.
From this point on, the line air pressure is continually
monitored by the WS Controller. The pressure
regulator and the solenoid valve remain closed
during this phase. The inlet valve is in the fully open
position as long as the compressor is running at 100
psig (6.9 bar) or below.
Modulating Mode
—100 to 110 PSIG (6.9 to 7.6 BAR)
If less than the rated capacity of compressed air is
being used, the service line pressure will rise above
100 psig (6.9 bar). The pressure regulator valve
gradually opens, directing air pressure to the inlet
control valve, reducing air entering the compressor
until it matches the amount of air being used. The
control system functions continually in this manner
between the limits of 100 to 110 psig (6.9 to 7.6 bar)
in response to varying demands from the service
line.
The integrated inlet valve has an orifice which vents
a small amount of air to the compressor inlet when
the pressure regulator controls the inlet control valve.
The orifice also bleeds any accumulated moisture
from the control lines.
Unload Mode
—In Excess of 110 PSIG (7.6 BAR)
When a relatively small amount or no air is being
used, the service line pressure continues to rise.
When it exceeds 110 psig (7.6 bar), the WS
Controller control system de-energizes the solenoid
valve allowing separator/sump tank air pressure to
be supplied directly to close the inlet valve.
Simultaneously, the
pneumatic signal to the blowdown valve. The
blowdown valve opens to the atmosphere, located in
the compressor intake, reducing the separator/sump
tank pressure to approximately 17 psig (1.2 bar). The
18
solenoid valve sends
check valve in the air service line prevents line
pressure from returning to the separator/sump tank.
When the line pressure drops to the low setting (cut-
in pressure; usually 100 psig (6.9 bar) on low
pressure (7 bar) compressors and 125 psig (8.6 bar)
on high pressure (9 bar) compressors, 150 psig (10.3
bar) on (10 bar) compressors, 175 psig (12.0 bar) on
(12 bar) compressors), the WS Controller energizes
the solenoid valve and allows the blowdown valve to
close. The re-energized solenoid valve again
prevents line pressure from reaching the inlet control
valve. Should the pressure begin to rise, the
pressure regulator will resume its normal function as
previously described.
Load/No Load Control
If desired by the customer, the compressor can be
set to operate load/no load without modulating
control. This control mode is often selected when a
large amount of compressed air storage (air tank) is
available. Using the WS Controller keypad, select
"load/no load control" from the menu. On a machine
rated for 100 psig (7 bar) the compressor will run in
the full load mode up to 100 psig (7 bar). If less than
the rated capacity is required, pressure will rise
above 100 psig and the WS Controller will de-
energize the solenoid valve, causing the compressor
to run in the unload mode. When the system
pressure falls to 90 psig (6.3 bar), the WS Controller
energizes the
compressor to return to the full load mode. The
compressor will thus operate to keep the system
pressure in the range of 90 to 100 psig (6.3 to 6.9
bar).
Automatic Operation
For applications with varied periods of time when
there are no air requirements, the WS Controller's
AUTOMATIC mode allows the compressor to
a
shutdown (time delayed) when no compressed air
requirement is present and restart as compressed air
is needed.
SECTION 2
solenoid valve, causing the