2
−
8
62-11389
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1. Solenoid Valve
2. Valve Stem
3. Gas Bypass Port
4. Spring Guide
5. Spring
6. Piston
7. Bypass Valve
8. Bleed Orifice
9. Strainer
10. Suction Manifold
11. Cylinder Discharge Valve
12. Valve Plate
13. Cylinder Suction Valve
14. Discharge Check Valve Assembly
15. Discharge Manifold
Figure 2
−
7 Compressor Cylinder Head Unloaded
b. Unloaded Operation
Pressure from the discharge manifold (item 15,
Figure 2
−
7) passes through the strainer (9) and bleed
orifice (8) to the back of the bypass valve piston (6). Un-
less bled away, this pressure would tend to close the pis-
ton against the spring (5) pressure and load the cylin-
ders in that head.
With the solenoid valve (1)
energized the solenoid valve
stem (2) will open the gas bypass port (3).
Discharge pressure will be bled to the suction manifold
(10) through the opened gas bypass port . A reduction in
pressure on the bypass piston valve will take place be-
cause the rate of bleed through the gas bypass port is
greater than the rate of bleed through the bleed orifice (8)
.
When the pressure behind the piston has been reduced
sufficiently, the valve spring will force the piston back,
opening the gas bypass from the discharge manifold to
the suction manifold.
Discharge pressure in the discharge manifold will close
the discharge piston check valve assembly (14) isolat-
ing the compressor discharge manifold from the individ-
ual cylinder bank manifold.
The unloaded cylinder bank will continue to operate fully
unloaded until the solenoid valve is de-energized and
the gas bypass port is closed.
