Abstract: A rotary air compressor of oil sealed type includes a stator containing a rotor, oil injectors arranged to inject oil into the interior of the stator, an oil sump connected by a first oil pathway to the oil injectors and an oil cooler situated in the first oil pathway. A thermally responsive valve situated in the first oil pathway is arranged to open only when the temperature of the oil has reached a predetermined value whereby no oil is injected through the oil injectors before the temperature of the oil has reached the said predetermined value.

Abstract: A positive displacement rotary compressor includes a stator which contains a rotor and has a stator inlet communicating with atmosphere via a first pilot operated valve and a stator outlet connected to a primary lubricant reservoir via a non-return valve and to an auxiliary lubricant reservoir via a second pilot operated valve and one or more lubricant injection orifices arranged to inject oil into the stator and connected to the primary reservoir via a third pilot operated valve and to the secondary reservoir. The compressor also includes a pilot control system responsive, in use, to the compressed air load to which the compressor is subjected and arranged to switch the first and third pilot operated valves from an open position to a closed position and the second pilot operated valve from a closed position to an open position when the compressed air load falls below a predetermined value. The auxiliary lubricant reservoir is always at substantially atmospheric pressure.

Abstract: An air compressor wherein oil mist lubricates a rotor stator in the compressor casing whereby an oil mist is produced in the compressed air provided with primary and secondary oil removal sections. The primary and secondary oil removal sections are connected by an oil separation manifold. The manifold and the secondary oil removal section are in a housing detachable from the main compressor housing. The main and detachable housings communicate with a tube which has apertures in its side wall at its inlet end which end communicates with the interior of the main housing and apertures in its side wall at its outlet end which end communicates with the manifold.

Abstract: A rotary oil sealed compressor including an unloader valve to restrict or close the compressor intake when the compressor pressure rises above the normal working pressure (i.e. when the demand for compressed air drops or ceases) and a minimum pressure valve arranged to ensure that the pressure within the compressor never drops below a predetermined minimum value, further includes venting means responsive to the rise in pressure in the compressed air supply line above a predetermined value exceeding the normal working valve arranged to vent the delivery and compression spaces of the compressor. Thus under no-load conditions the pressure within the compressor is reduced to a relatively low level which considerably reduces the power consumed when the compressor is idling.