Section 5
COMPRESSOR SYSTEMS
22
Figure 5-5 Air Inlet System
pressure valve now isolates the sump vessel from
the service line.
If the Supervisor II module is operating on an “
I
”
mode, the unit runs unloaded until the line pressure
falls below 100 psig (6.9 bar), at which point it pro-
ceeds to the Normal Modulating Mode. If on the oth-
er hand, the Supervisor II module is operating in the
“
A
” mode, the unit runs unloaded for a pre--set
length of time, and unless the line pressure falls be-
low the 100 psig (6.9 bar) level, it stops at the end of
this period. Once the line pressure falls below the
100 psig (6.9 bar) level, the compressor automati-
cally restarts, followed by package operation in the
Load mode.
When the line pressure drops back to 100 psig (6.9
bar) due to an increase in the air demand, Supervi-
sor II energizes the solenoid valve allowing the air
pressure behind the inlet poppet valve to be vented
through the solenoid valve exhaust port. The blow-
down valve closes, and the inlet poppet valve
opens. Also the air pressure at the spiral valve ac-
tuator diaphragm is reduced through a vent hole at
the spiral valve differential pressure regulator, and a
spring in the actuator causes the spiral valve to re-
turn to the full load (maximum) position.
5.7 AIR INLET SYSTEM, FUNCTIONAL DE-
SCRIPTION
Ref er t o F igure 5 -- 5. T he compressor inlet syst em
consists of a
single--stage, dry--type air filter
,an
inlet poppet valve
, and an
adaptor piece
which
mounts both devices to the compressor inlet flange.
Optionally, a two--stage, heavy--duty, dry--type filter
with inertial dust separation and collection, is avail-
able for added air filtration and sound attenuation.
When the pressure drop across the filter element(s)
exceeds a level of 15 in. of water column, a switch
contact opens in the Supervisor II module and a filter
maintenance annunciation is displayed.
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