Section 2
DESCRIPTION
11
ate in the same manner except for the stated pres-
sures.
START MODE - 0 TO 50 PSIG (0 TO 3.5 BAR)
When the compressor START button is depressed,
the sump pressure will quickly rise from 0 to 50 psig
(0 to 3.5 bar). During this period, the spiral valve
fully closes, while the inlet butterfly valve fully
opens. As a result, the compressor runs at full
capacity.
FULL LOAD MODE - 50 TO 100 PSI (3.5 TO 6.9
BAR)
When the sump pressure rises above 50 psi (3.5
bar), the minimum pressure valve opens, allowing
compressed air to flow into the service line. Both
the spiral valve as well as the inlet butterfly valve
remain in the full load position as long as the com-
pressor is running at 100 psi (6.9 bar) or below.
MODULATION MODE - 100 to 110 PSIG (6.9 TO
7.6 BAR)
As air demand drops below the rated capacity of
the compressor, the line pressure will rise above
100 psig (6.9 bar). As a result, the differential pres-
sure regulator for the spiral valve gradually opens
applying air pressure to the spiral valve actuator. Air
pressure at the actuator assembly expands the
diaphragm. The rack, which engages with the pin-
ion mounted on the spiral valve shaft assembly,
begins to stroke. This results in a rotary motion. As
the spiral valve rotates, it starts opening the bypass
ports gradually. Excess air is then being returned
back to suction. Now the compressor is compress-
ing only that amount of air which is being used. As
air demand keeps on dropping further, the spiral
valve opens gradually until all the bypass ports are
fully open. At this point, the spiral valve has moved
into the unload position.
The spiral valve provides a modulation range from
50 to 100%. During this period, the pressure rises
approximately from 100 to 108 psi (6.9 to 7.5 bar).
As the air pressure exceeds 108 psi (7.5 bar), the
differential pressure regulator controlling the
Sullicon Control opens. This allows the air pressure
to the diaphragm chamber of the Sullicon Control
which starts to close the inlet butterfly valve partial-
ly. The inlet butterfly valve provides modulating
range from 40 to 50%. During this period, the pres-
sure rises approximately from 108 to 110 psi (7.5 to
7.6 bar). Within this range, the spiral valve remains
in the unload position.
UNLOAD MODE - IN EXCESS OF 110 PSI (7.6
BAR)
When a relatively small amount, or no air is being
used, the service line pressure keeps on rising.
When it exceeds 110 psig (7.6 bar), the air pressure
switch opens de-energizing the solenoid valve. The
line pressure through the solenoid valve holds inlet
butterfly valve closed, and at the same time it
opens the blowdown valve. Reduced sump pres-
sure during blowdown results in low unload power
consumption. While the compressor is running
unloaded, the inlet butterfly valve remains in the
unload position. As the line pressure fluctuates
between 100 and 110 psi (6.9 to 7.6 bar), the spiral
valve will modulate.
When the line pressure falls to 100 psi (6.9 bar),
due to an increase in the air demand, the air pres-
sure switch closes. The solenoid valve is then ener-
gized allowing the air pressure behind the Sullicon
Control to be vented through the solenoid valve
exhaust port. The blowdown valve closes, and the
inlet butterfly valve opens. Also at this time, the air
pressure at the diaphragm of the spiral valve actu-
ator has been released through a vent hole in the
spiral valve differential pressure regulator. This
allows the spiral valve to close as a result of the
movement of the rack and pinion. The compressor
is now running again in full load mode. The spiral
valve as well as the inlet butterfly valve are in full
load position.
For a compressor with varied periods of time when
there are no air requirements, a "Dual Control"
option is available. This option allows you to set the
compressor in an automatic position whereby the
compressor will shut down (time delayed) when no
compressed air requirement is present and restart
as compressed air is needed.
2.7 AIR INLET SYSTEM, FUNCTIONAL DESCRIP-
TION
Refer to Figure 2-5. The compressor inlet system
consists of a dry-type air filter, a restriction gauge
and an air inlet valve.
The restriction gauge, located on the compressor
instrument panel, indicates the condition of the air
filter. When the pointer reaches the red zone, filter
maintenance is required.
The butterfly-type air inlet valve directly controls the
amount of air intake by the compressor in response
to the operation of the Sullicon Control (Section
2.6).
2.8 INSTRUMENTATION, FUNCTIONAL DESCRIP-
TION
Refer to Figure 2-6 for specific location of parts
described. The panel group consists of a number of
gauges, buttons and status indicator lights. Refer to
To Next Page
Loading...
