Sullair 20/12 500 CFM, Operator'S Manual And Parts List

Page: 13 / 66

Section 2
DESCRIPTION
9
Figure 2-4 Compressor Discharge System (Typical)
parallel with other compressors tied to a large sys-
tem. It is recommended that an optional gate--type
service valve be used downstream of the check
valve before the point at which service lines and
hoses are connected.
An indicator, located on the instrument panel, sig-
nals red if abnormal pressure drop through the sep-
arator develops. At this time, separator element re-
placement is necessary.
2.6 CAPACITY CONTROL SYSTEM, FUNCTIONAL
DESCRIPTION
Ref er t o F igur es 2 -- 5 and 2 -- 6 . T he pur pos e of t he
compressor control system is to regulate the com-
pressor air intake to match the amount of com-
pressed air being used. At a 0 to 10 percent air out-
put, the control system will automatically blow down
the compressor and greatly reduce the unload pow-
er consumption.
The Control System consists of a pneumatic ac-
tuator cylinder , a butterfly valve (located on the
compressor air inlet), a pilot pressure regulator
valve , a solenoid pilot valve , closed inlet sole-
noid valve , Sullicon Control and a blowdown
valve .
The functional description of the Control System is
described below in five distinct phases of compres-
sor operation. For explanation purposes, this de-
scription will apply to compressors with an operating
pressure range of 340 to 360 PSIG (2344 to
2482kPa). A compressor with any other pressure
range would operate in the same manner except for
the stated pressures.
START MODE -- 0 TO 160 PSIG (0 TO 1103kPa)
When the compressor START button is depressed,
the pressure will quickly rise from 0 to 160 PSIG (0 to
1103kPa). During this period, both the pressure reg-
ulator and the pilot valve are closed and the inlet cyl-
inder is inoperative. Until the closed inlet timer is sat-
isfied, the inlet cylinder section remains withdrawn
holding the inlet butterfly valve closed (start Mode
A). When the timer is satisfied, the closed inlet sole-
noid valve opens allowing the cylinder to extend,
opening the butterfly valve fully and the compressor
then pumps at full rated capacity (start Mode B). The
rising compressed air pressure is isolated from the
service line in this phase by the minimum pressure
valve, set at approximately 160 PSIG (1103kPa).
NORMAL OPERATING MODE -- 160 TO 340 PSIG
(1103 TO 2344kPa)
When the sump pressure rises above 160 PSIG
(1103kPa), the minimum pressure valve opens and
delivers compressed air to the service line. From
this point on, the line air pressure is continually mon-
itored by a line pressure gauge. The pilot pressure
regulator and the pilot valve remain closed during
this phase, keeping the Sullicon Control inactive.