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AIR FLOW
Air drawn through the airfilter (AFce) into the compressor
element (CE) is compressed. At the element outlet,
compressed air and oil pass into the air receiver/oil
separator (AR/OS).
The check valve (CV) prevents blow-back of compressed
air when the compressor is stopped. In the air receiver/oil
separator (AR/OS), most of the oil is removed from the
air/oil mixture.
The oil collects in the receiver and on the bottom of the
separator element.
The air leaves the receiver via a minimum pressure valve
(MPV) which prevents the receiver pressure from
dropping below the minimum working pressure, even
when the air outlet valves are open (specified in section
Limitation). This ensures adequate oil injection and
prevents oil consumption. The minimum pressure valve
(MPV) also functions as a check valve.
The system comprises temperature sensors (TS),
regulating pressure sensors (RPS) and a working pressure
sensor (WPS).
OIL SYSTEM
The lower part of the air receiver (AR) serves as oil tank.
Air pressure forces the oil from the air receiver/oil
separator (AR/OS) through the oil cooler (OC), the oil
filters (OFc) and the oil stop valve (OSV) to the
compressor element (CE).
When the compressor is stopped and / or there is no
pressure in the system, the oil stop valve (OSV) prevents
the oil from flowing back into the compressor element.
The thermostatic by-pass valve (TBV) starts opening
when the oil temperature is 70 °C (158 °F).
The compressor element has an oil gallery in the bottom of
its casing. The oil for rotor lubrication, cooling and sealing
is injected through holes in the gallery.
Lubrication of the bearings is ensured by oil injected into
the bearing housings.
The injected oil, mixed with the compressed air, leaves the
compressor element and re-enters the air receiver, where it
is separated from the air as described in section Air flow.
The oil that collects in the bottom of the oil separator
element is returned to the system through a scavenging
line (SL), which is provided with a flow restrictor.
The oil filter by-pass valve opens when the pressure drop
over the filter is above normal because of a clogged filter.
The oil then by-passes the filter without being filtered. For
this reason, the oil filter must be replaced at regular
intervals (see section Preventive maintenance schedule).
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