13-11-607 Page 30
CAUTION
Never paint, lubricate or alter a relief valve. Do not plug vent or restrict
discharge.
WARNING
Operation of unit with improper relief valve setting can result in severe personal
injury or machine damage. Insure properly set valves are installed and
maintained.
Blowdown Valve
(g) - This solenoid valve provides purging air to the compressor during unloaded
operation. It also depressurizes the air/water reservoir during unloaded or halted operation. It is
governed by the AUTO SENTRY W controller.
Aux. Blowdown Valve
(h) – This solenoid valve depressurizes rapidly the air/water reservoir during the
initial phase of the unloading cycle. It is energized by the auxiliary pressure switch.
Aux. Pressure Switch
(j) – This device senses the air reservoir pressure and controls the closing level
of the auxiliary blowdown valve during the latter phase of the unloading cycle. Its setting (see Figure 4-3,
page 30) is adjusted to maintain the compressor inlet pressure within 0 to 11” Hgv during unloaded
operation. It is housed in the starter control box, but it is independent from the AUTO SENTRY W
controller.
Model Power – bhp
20
20
20
25
25
25
30
30
30
Line Pressure – psig
100
125
150
100
125
150
100
125
150
Receiver Pressure – psig
41
32
26
46
40
32
51
48
37
Figure 4-3 – AUXILIARY PRESSURE SWITCH/RECEIVER UNLOADED PRESSURE TABULATION
Check Valve (Aux Blowdown)
(i, next to b) – This check valve prevents back flow of air from the
airend immediately after halting operation.
Check Valve (Main Discharge)
(k)
–
This check valve prevents back flow of air from the customer’s air
line when the unit stops, unloads, or is shut down.
Inlet Valve
(b) – This device modulates the flow of air entering the compressor and checks the back
flow of air immediately after halting compressor operation. Its piston assembly is energized with air from
the subtractive valve (during modulation) or with air from the main blowdown valve (during unloaded
operation).
Subtractive Valve
(q) – This device produces a variable pneumatic signal (0 to 20 psig) in proportion to
a system pressure rise (0 to 10 psig) above its set pressure. It is used to control the flow modulating
action of the inlet valve. The device is adjusted as follows:
•
Loosen the locknut securing the adjusting stem of the subtractive valve and screw the latter
in several turns – this will prevent the valve from opening during adjustment. This is also the
way to deactivate the device by adjusting its pressure setting beyond the expected package
operating range.
Summary of Contents for PUREAIR EWC99C
Page 7: ...13 11 607 Page 2 Figure 1 2 PACKAGE ILLUSTRATION 307EWC797 B Ref Drawing...
Page 8: ...13 11 607 Page 3 Figure 1 3 AIR WATER SCHEMATIC 308EWC797 F Ref Drawing...
Page 25: ...13 11 607 Page 20 Figure 4 2 FLOW CHART FOR SETUP PROGRAMMING 300EWC1255 Ref Drawing...
Page 38: ...13 11 607 Page 33 Figure 4 4 WIRING DIAGRAM FULL VOLTAGE 305EWC546 B Ref Drawing Page 1 of 2...
Page 39: ...13 11 607 Page 34 305EWC546 B Ref Drawing Page 2 of 2...
Page 41: ...13 11 607 Page 36 306EWC546 B Ref Drawing Page 2 of 2...
