Abstract: A single screw compressor comprises a main rotor and at least one gate rotor, a casing for the main rotor having a discharge port at a discharge end of the casing, and a slide slidable within a bore in the casing adjacent the main rotor. The slide has a cut-out (6) between first (2) and second (4) sealing parts of the slide, the slide is slidable between a high volume ratio position where the cut-out (6) is within the casing and provides a path to the discharge port, and a low volume ratio position where the slide is beyond the discharge end of the casing to provide a fixed discharge path in the bore of the casing.

Abstract: A ducted separator in a compressor-based cooling assembly is connected to an oil/gas outlet of the compressor. The ducted separator is a pipe with at least one bend in it which collects oil in a manner which can achieve 98% oil carry over efficiency. The ducted separator may optionally be connected to a second phase separator such as a centrifugal cylinder. In that case, the height of the centrifugal cylinder can be significantly reduced compared with conventional arrangements. Alternatively, a simpler impingement surface such as one or more baffles may be used as the second phase separator or just a collection chamber.

Abstract: A ducted separator in a compressor-based cooling assembly is connected to an oil/gas outlet of the compressor. The ducted separator is a pipe with at least one bend in it which collects oil in a manner which can achieve 98% oil carry over efficiency. The ducted separator may optionally be connected to a second phase separator such as a centrifugal cylinder. In that case, the height of the centrifugal cylinder can be significantly reduced compared with conventional arrangements. Alternatively, a simpler impingement surface such as one or more baffles may be used as the second phase separator or just a collection chamber.

Abstract: A slide for use in a single screw compressor is disclosed. The screw compressor is arranged to vent the flutes of its main rotor at all times, without having to provide a check valve in the discharge port of the main rotor casing. An additional outlet port in the casing vents gas from the discharge ends of the flutes into the body of the slide instead of to the discharge port. The vented gas is guided to an exit port of the slide, from where it can reach either the discharge port or the bypass port of the casing at all times during use of the compressor and under all loading conditions. The design of the disclosed slide further allows the use of an offset discharge port in the casing, in relation to the main rotor.

Abstract: A single screw compressor is arranged to vent the flutes of its main rotor at all times, without having to provide a check valve in the discharge port of the main rotor casing. An additional outlet port in the casing vents gas from the discharge ends of the flutes into the body of a slide instead of to the discharge port. The vented gas is guided to an exit port of the slide, from where it can reach either the discharge port or the bypass port of the casing at all times during use of the compressor and under all loading conditions. The design of the slide further allows the use of an offset •? discharge port in the casing, in relation to the main rotor. This means that pressure acting through the discharge port in use of the compressor tends to press the slide against another structure than the main rotor, for instance a bearing housing, giving better support to the slide. The slide also provides an improved oil delivery arrangement.

Abstract: A valve comprises a housing (1) having an inlet (4) and an outlet (5), and a pressure sensing port (8). A piston (6) slides in a part (3) of the housing (1) in response to a difference between a first fluid pressure at the pressure sensing port on the one side of the piston, and a second fluid pressure at the inlet and/or outlet on the other side of the piston (6). A valve member (7) carried by the piston is operable thereby to close the inlet (4) when said second fluid pressure is less than a value sufficiently greater than said first fluid pressure. The valve member (7) is movable with respect to the piston (6) to facilitate closing of the inlet (4), in response to a fluid flow from the housing (1) to the inlet (4), when the piston is not acting to close the inlet.

Abstract: A method of improving the efficiency of a pair of first and second scroll refrigeration compressors, at least the second of which includes an intermediate port is characterized in that the delivery of the first scroll compressor is fed into the intermediate port of the second compressor at a pressure corresponding to the intermediate port in the compression process occurring in the second scroll compressor.