Control System, Functional Description - Sullair ES-8-15L Operator's Manual And Spare Parts List

Figure 4-2 Encapsulated Compressor System
4.6 CONTROL SYSTEM, FUNCTIONAL DE-
SCRIPTION
The purpose of the compressor control system is to
regulate the amount of air being compressed to
match the amount of compressed air being used.
The capacity control system consists of a solenoid
valve, regulator valve and an inlet valve. The
functional description of the control system is de-
scribed below in 4 distinct phases of operation. The
following description text applies to all Series ES-8
compressors. For explanatory purposes, this de-
scription will apply to a compressor with an operat-
ing range of 100 to 110 psig (6.9 to 7.6 bar). A com-
pressor with any other pressure range would oper-
ate in the same manner except stated pressures.
START MODE - 0 TO 60 PSIG (0 TO 4.2 bar)
When the compressor "I" pad is depressed, the
sump pressure will quickly rise from 0 to 60 psig (0 -
4.2 bar). During this period, both the pressure regu-
lator and the solenoid valve are closed, the inlet
valve is fully open and the compressor 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 60
COMPRESSOR SYSTEMS
psig (4.2 bar).
FULL LOAD MODE - 60 TO 100 PSIG (4.2 TO 6.9
bar)
When the compressed air pressure rises above 60
psig (4.2 bar), the minimum pressure valve opens
allowing compressed air to flow into the service line.
From this point on, the line air pressure is continually
monitored by the Supervisor. The pressure regula-
tor 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.
Section 4
15