Patent ID: 6860730

Claim:
A screw compressor unloading system comprising: a screw compressor including an air inlet and an air outlet, the air inlet having an air inlet intake valve for closing the air inlet; a vacuum device of substantially smaller maximum capacity than the screw compressor, the vacuum device having an air inlet and an air outlet, the air inlet of the vacuum device being communicable with the air outlet of the screw compressor to enable the vacuum device to unload the screw compressor by sucking air out of the screw compressor when the air inlet intake valve is closed; and an air reservoir connected to the air outlet of the screw compressor, and a non-return valve arranged to prevent backflow of air from the air reservoir to the air outlet of the screw compressor; the air outlet of the vacuum device being connected to supply compressed air to the air reservoir, such that the vacuum device constitutes a pressure booster.