4 – 14
VSG/VSSG • Installation, Operation and Maintenance Manual •Vilter/Emerson • 35391STG
Section 4 • Operation
Figure 4-14. Coalescing Oil Return Line
Coalescing Oil Return Line
Needle
Valve
Sight-Glass
Shut-Off
Valve
Check Valve
Coalescing Oil Return Line Setup
Over time, oil will accumulate on the coalescing side
of the oil separator. As a result, an oil return line with a
shut-off valve, sight-glass, check valve and needle valve
are installed between the coalescing side and compres-
sor to return this oil back to the compressor.
To adjust the return
fl
ow, proceed with the follow
procedure:
NOTE
Do not fully open the needle valve unless directed by
Vilter Customer Service. Leaving the needle valve fully
open will reduce ef
fi
ciency of the compressor unit.
1. Open shut-off valve on coalescing side of oil separa-
tor, see Figure 4-14.
2. While the unit is in operation, crack open needle
valve and observe oil
fl
ow through sight-glass.
3.
Slowly open needle valve more until a small amount
of oil is seen in the sight-glass.
NOTE
The sight-glass should never be full with oil.
4. Periodically check oil in the sight-glass and ensure
that there is
fl
ow.