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UNLOAD - IN EXCESS OF 125 PSIG (8.6 BAR)
LINE PRESSURE
When no air is being used,the service line pressure
rises to the setting (cut--out pressure) of the pres-
sure switch. the pressure switch opens, interrupting
the electrical power to the solenoid valve. At this
time, the solenoid valve allows dry sump tank air
pressure or service air pressure through a shuttle
valve to be applied directly to the inlet valve piston
and keep it closed. Simultaneously, the solenoid
valve sends a pneumatic signal to the blowdown
valve. The blowdown valve opens the sump to the
compressor intake reducing the sump pressure to
approximately 25 to 27 psig (1.7to 1.9 bar). The
check valve in the air service line pressure prevents
line pressure from returning to the sump.
When the line pressure drops to the low setting (cut--
in pressure) of the pressure switch (usually 115 psig
[7.9 bar]), the pressure switch closes, re--energizing
the 3--way solenoid valve and allowing the blow-
down valve to close. The re--energized solenoid
valve again prevents pressure from reaching the in-
let valve. The inlet valve is fully open and the com-
pressor delivers full rated capacity. Should the pres-
sure begin to rise, the pressure regulator will resume
its normal function as previously described.
To accommodate varied periods of time when there
are not any air requirements, "Dual--Control" is uti-
lized. This feature allows you to set the compressor
in an automatic position whereby the compressor
will shut down when no compressed air requirement
is present and restart as compressed air is needed.
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.
2.7 AIR
INLET
SYSTEM,
SCRIPTION
Refer t o F igur e
2 --
6. T he C ompr es s or I nlet Sy s t em
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 ( s ee Modulating Mode,
Elec tr o- Mec hanic
al] or
per v is o r I
l]) . T h e inlet v a lv e a ls o a c t s a s a c hec k
valve, thus preventing reverse rotation when the
compressor is shut down.
FUNCTIONAL
DE-
Sec t ion 2.6 [Standar d
Sec t ion 2.7 [O ptional Su-
Figure 2-6 Air Inlet System
16 SERIES
AIR INLET
VALVE
AIR FILTER
12 SERIES
AIR FILTER
!
"The Plastic Pipe Institute recommends against the
use of thermoplastic pipe to transport compressed
air or other compressed gases in exposed above
ground locations, e.g. in exposed plant piping." (I)
Sullube 32 should not be used with PVC piping sys-
tems. It may affect the bond at cemented joints. Cer-
tain other plastic materials may also be affected.
(I) Plastic Pipe Institute, Recommendation B,
Adopted January 19, 1972.
2.8 INSTRUMENT PANEL GROUP, FUNCTIONAL
DESCRIPTION-
STANDARD
CHANICAL CONTROLLER
The electro-mechanical controller responds to sig-
nals from traditional pressure switch sensors and
provides stop/start, automatic control, common
fault indication, sensor bypass timing, wye- -
delta transition timing, and facilitates selectable
Section 2
DESCRIPTION
AIR INLET
VALVE
WARNING
ELECTRO-ME-
11
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