SECTION 2
®SULLAIR®
12
3700 Operator’s Manual and Parts List
 Figure 2-4
1. Air Outlet
2. Pressure Regulator
3. Solenoid Valve
4. Air Inlet
5. Blowdown Valve
6. Minimum Pressure / Check Valve
7. Sump Tank
F i g u r e 2 - 4      
Sequencing Control System 
FULL LOAD MODE - 50 TO 100 PSIG (3.4 TO 
6.9 BAR)
When the compressed air pressure rises above 50 psig 
(3.4 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 microprocessor controller. The pressure regulator 
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.
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