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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 Limitations). This ensures
adequate oil injection and prevents oil
consumption. The minimum pressure
valve (MPV) also functions as a check
valve.
The system comprises temperature switch
(TS).
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 (OF) and the
oil stop valve (OSV) to the compressor
element (CE).
When the compressor is stopped check
valve incorporated in the unloader valve
prevents the oil from flowing back into the
compressor element to air flow.
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 Part of the control
air is vented to atmosphere, and any
condensate discharged, through the vent
holes.. 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
(FR).
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 for
the compressor).
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