Howden WRV, Руководство по обслуживанию

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2.3 DESCRIPTION OF A GAS SYSTEM FOR A TYPICAL REFRIGERATION COMPRESSOR SET
Gas is drawn into the compressor through a non-return valve and then a strainer is fitted directly on
the inlet flange and discharged into an oil tank/separator. The non-return valve is necessary to
prevent the compressor being “motored” in the reverse direction when it is stopped with high gas
pressure at the outlet.
If necessary, a second non-return valve is positioned at the outlet of the tank to prevent the entry of
gas or liquid refrigerant.
Primary separation of the oil mixed with the gas is achieved in the tank, secondary separation takes
place in a wire mesh element separator positioned close to the tank outlet.
In some separator designs the wire mesh is replaced by a separator cartridge.
The separated oil drains into the oil tank. A further secondary separator vessel may also be fitted
where a very high separation efficiency is required. The oil separated is usually drained into the
compressor through a small bore pipe which can be fitted with a protective filter and an isolating
valve.
2.4 DESCRIPTION OF AN OIL SYSTEM FOR A TYPICAL REFRIGERATION COMPRESSOR SET
Oil at outlet pressure is drawn from the tank by the oil pump, passed through a cooler and micronic
filters to the manifold where it is fed to the bearings, balance piston, shaft seal, compression
chamber and hydraulic actuator.
When liquid refrigerant injection is used there is no oil cooler.
A differential pressure relief valve in the system before the filters maintains a manifold pressure in
the range of 30 psi (2 kg/cm²) for a standard range co
mpressor set and 40 psi (2.7 kg/cm²) for an ‘H’
designated compressor set. When the compressor operates on a continuous duty, duplex micronic
filters may be fitted, allowing one filter element to be changed while the other is in operation.
Approved lubricating oils for refrigeration compressors are listed under Section 2.5.