Air Inlet System, Functional Description; Instrument Panel Group, Functional - Sullair LS-100L Operator's Manual

Section 2
DESCRIPTION
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 125 to 135 psig (8.6 to 9.3 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 135 PSIG (9.3
BAR)
When a relatively small amount or no air is being
used, the service line pressure continues to rise.
When it exceeds 135 psig (9.3 bar), the Supervisor
II 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 25 to 27 psig (1.7 to 1.9 bar). The check valve in
the air service 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]
on high pressure ["H"] compressors, 150 psig [10.3
bar] on ["HH"] compressors, 175 psig [12.0 bar]
["XH"]. Supervisor II energizes the solenoid valve
and allows the blowdown valve to close. The re-
energized solenoid valve again prevents line pres-
sure from reaching the inlet control valve. Should
the pressure begin to rise, the pressure regulator
will resume its normal function as previously
described.
AUTOMATIC OPERATION
For applications with varied periods of time when
there are no air requirements, Supervisor II's
AUTOMATIC mode allows the compressor to shut-
down (time delayed) when no compressed air
requirement is present and restart as compressed
air is needed.
2.8 AIR INLET SYSTEM, FUNCTIONAL DESCRIP-
TION
Refer to Figure 2-5. The Compressor Inlet
System consists of a dry-type air filter, a restric-
tion gauge and an air inlet valve.
The restriction gauge indicates the condition of the
air filter by showing red when filter maintenance is
12
Figure 2-5 Air Inlet System
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 regu-
lator (see Modulating Mode, Section 2.6 [Standard
Elector-Mechanical] or Section 2.7
Supervisor Il]). 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

DESCRIPTION-
MECHANICAL CONTROLLER
The electro-mechanical controller responds to sig-
nals from traditional pressure switch sensors and
provides stop/start, common fault indication, sensor
bypass timing, wye-delta transition timing, and facil-
itates selectable automatic restart after power fail-
ure. Two-wire remote Stop/Start input is provided.
Refer to Figure 2-6
[Optional
STANDARD ELECTRO-
for specific location of parts