Air Inlet System, Functional Description; Instrument Panel Group, Functional Description Standard Electro-Mechanical Controller - Sullair LS-120 series Operators Manual And Parts Lists

Section 2
DESCRIPTION
rpm has been achieved. During this period, both
the pressure regulator and the solenoid valve are
closed, the inlet valve is fully open and the com-
pressor pumps at full rated capacity. The rising
compressor air pressure is isolated from the service
line in this phase by the minimum pressure valve
set at approximately 50 psig (3.4 bar).
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 continu-
ally monitored by the Supervisor 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 pressure regulator has an orifice which vents a
small amount of air to the atmosphere when the
pressure regulator controls the inlet control valve.
The orifice also bleeds any accumulated moisture
from the pressure regulator.
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 Supervisor
Control System de-energizes the solenoid valve
allowing sump air pressure to be supplied directly to
close the inlet valve. Simultaneously, the solenoid
valve sends a pneumatic signal to the blowdown
valve. The blowdown valve opens to the atmos-
phere, reducing the sump pressure to approximate-
ly 20 psig (1.4 bar). The check valve in the air serv-
ice line prevents line pressure from returning to the
sump.
When the line pressure drops to the low setting
(cut-in pressure; usually 100 psig [6.9 bar] on low
pressure ["L"] compressors and 125 psig [8.6 bar]
12
on high pressure ["H"] compressors, 150 psig [10.3
bar] on ["HH"] compressors, 175 psig [12.0 bar]
["XH"] . Supervisor Controller energizes the sole-
noid 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 reg-
ulator will resume its normal function as previously
described.
AUTOMATIC OPERATION
For applications with varied periods of time when
there are no air requirements, Supervisor's AUTO-
MATIC mode allows the compressor to shutdown
(time delayed) when no compressed air require-
ment is present and restart as compressed air is
needed.
2.8 AIR INLET SYSTEM, FUNCTIONAL DESCRIP-
TION
Refer to Figure 2-6. 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 instrument
panel), indicates the condition of the air filter by
showing red when filter maintenance is required.
The poppet-type modulating air inlet valve directly
controls the amount of air intake to the compressor
in response to the operation of the pressure regula-
tor (see Modulating Mode, Section 2.6 [Standard
Electro-Mechanical] or Section 2.7 [Optional
Supervisor Controller]). The inlet valve also acts as
a check valve, thus preventing reverse rotation
when the compressor is shut down.
"The Plastic Pipe Institute recommends against
the use of thermoplastic pipe to transport com-
pressed air or other compressed gases in
exposed above ground locations, e.g. in exposed
plant piping." (I)
Sullube should not be used with PVC piping sys-
tems. It may affect the bond at cemented joints.
Certain other plastic materials may also be affect-
ed.
(I) Plastic Pipe Institute, Recommendation B,
Adopted January 19, 1972.
2.9 INSTRUMENT PANEL GROUP, FUNCTIONAL DE-
SCRIPTION- STANDARD ELECTRO-MECHANI-
CAL CONTROLLER
Refer to Figure 2-7
described. For information on Supervisor Controller
panel group, consult the Supervisor Controller
Manual.
The Electro-mechanical Controller Instrument
for specific location of parts