Gardner Denver VS-11, Operating And Service Manual, Page: 42 / 68

13-18-606 Page 41
Low Air Demand and Package Operation – During periods of very low air demand, such as when the package
is operated in short cycles, the oil system may not reach a high enough temperature to keep water vapor from
condensing, in spite of the oil mixing valve bypassing all flow around the heat exchanger.
Under these conditions, it is recommended that the package operation be prolonged after each unload condition
is achieved – this can be easily accomplished by adjusting the “Auto Timer” option in the AirSmart controller.
Refer to the AirSmart controller user’s manual 13-17-600 for detailed programming instructions of this parameter
and adjust the “Auto Timer” parameter to a value of at least 5 minutes.
OIL SEPARATION RESERVOIR / COALESCING ELEMENT - This device serves multiple functions in the
compressor package:
•
Air/oil centrifugal separation - The bulk of the liquid oil is separated, by change of direction, impingement
and additional centrifugal effects, away from the compressed air and aerosol streams, and is then gravity-
collected at the bottom of the sump.
•
Oil degassing and holding - The sump has sufficient holding capacity to degas the oil mass before it is
drained off on its way to cooling, filtering and re-injection. It also serves as a storage volume for the oil mass
migrating from higher elevations (e.g., oil cooler, compressor casings, and piping).
•
Air/oil final separation - The aerosols and compressed air streams are led to the upper portion of the sump,
where the coalescing element resides. The fine droplets of oil (aerosol) are trapped in the element media,
coalesced, then gravity-drained, through a low-point connection and associated tubing (oil return line) into a
lower pressure region of the compressor.
Separation performance - The package oil separation system has been designed to yield 2 ppm total oil
carryover at the discharge of the air/oil reservoir – the oil content level at the discharge of the package will be
lower and will depend on the amount of moisture rejected by the aftercooler.
This high level of performance will be affected by the following typical offset conditions:
•
Contaminated (e.g., dirt, varnish, moisture) or damaged (e.g., ruptured) coalescing element.
•
Contaminated (e.g., dirt, varnish, moisture) or inadequate oil in use.
•
High oil level in air/oil reservoir.
•
Blockages of oil return line strainer or orifice.
•
Abnormally frequent or fast depressurization cycles - leading to oil foaming.
Oil separator element life cannot be predicted; it will vary greatly depending on the conditions of operation, the
quality of the oil used and the maintenance of the oil and air filters. The condition of the separator can be
determined by pressure differential gauging or by inspection.
Oil Coalescing Element Monitoring - The AirSmart controller keeps track of the pressure differential across the
coalescing element. A pressure differential of 8 psi will trigger a service advisory to change the element and a
pressure differential of 15 psi will initiate a system shutdown.
Using an oil separator element at excessive pressure differential can cause
damage to equipment. Replace the separator when the "Change Separator"
advisory appears.
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