A method of monitoring a volume index valve of a compressor is provided. The method includes recording a first reading of an operating condition of the compressor when the volume index valve is in a first position. The method also includes switching the volume index valve to a second position. The method further includes recording a second reading of the operating condition of the compressor when the volume index valve is in the second position. The method yet further includes calculating a difference between the first reading and the second reading. The method also includes comparing the difference to a predetermined threshold difference to determine if the volume index valve is moving between the first position and the second position in a desired manner.

A vacuum pumping system includes a plurality of positive displacement vacuum pumps, and more particularly a plurality of positive displacement vacuum pumps working in parallel. The vacuum pumping system includes a management unit that carries out a synchronized control of all the positive displacement vacuum pumps of the vacuum pumping system and thus allows to check possible risk of contamination of the vacuum pumping system and carry out, if needed, the necessary corrective actions without requiring any modification to the construction of the vacuum pumping system.

Systems, methods, and computer-readable mediums are provided for improving the efficiency of a filter-type oil separator in a cooling system including a compressor that pumps a mixture of lubricating oil and refrigerant through the filter-type oil separator. The filter type oil separator is configured to receive a first portion of the mixture from the compressor, and a bypass line is configured to bypass a second portion of the mixture around the filter-type oil separator. The bypass line ensures a sufficient amount of oil is present in the compressor.

A method of monitoring a volume index valve of a compressor is provided. The method includes recording a first reading of an operating condition of the compressor when the volume index valve is in a first position. The method also includes switching the volume index valve to a second position. The method further includes recording a second reading of the operating condition of the compressor when the volume index valve is in the second position. The method yet further includes calculating a difference between the first reading and the second reading. The method also includes comparing the difference to a predetermined threshold difference to determine if the volume index valve is moving between the first position and the second position in a desired manner.

A screw compressor (100), comprising a screw rotor (110) and a spool valve (120). The screw rotor (110) comprises a suction head end (111) and an exhaust tail end (112). Gas is sucked in from the suction head end (111) and compressed gas is discharged from the exhaust tail end (112). The spool valve (120) comprises a working side (125) for sealing a compression chamber of the screw rotor (110). The working side (125) comprises a spool valve head end (121) and a spool valve tail end (122) and can do a reciprocating motion along the axis direction of the screw rotor (110). When the spool valve (120) moves to a suction capacity adjusting position (240), the spool valve head end (121) is located at the inner side of the suction head end (111) of the screw rotor (110), and a suction capacity adjusting distance (D2) is formed between the spool valve head end (121) and the suction head end (111) so that the suction capacity of the screw compressor is adjusted. The suction capacity of the screw compressor (100) can be adjusted by means of the spool valve (120), so that the problem of motor temperature and exhaust gas temperature limits of conventional variable frequency screw sets is effectively solved and the operational range and the load regulation ability of the screw compressor are expanded.

Disclosed is a method for control loop performance monitoring in a variable frequency drive. A set of data is inputted to one or more control loop performance monitoring algorithms comprised in the variable frequency drive, wherein the set of data comprises at least a measured value of a process variable, a target value for the process variable, a set of controller input parameters, and a controller output. An output from each of the one or more control loop performance monitoring algorithms is obtained based at least partly on the set of data. One or more key performance indicator values indicative of control loop performance are determined based at least partly on the output from each of the one or more control loop performance monitoring algorithms. The set of controller input parameters is adjusted based at least partly on the one or more key performance indicator values.

Systems, methods, and computer-readable mediums are provided for improving the efficiency of a filter-type oil separator in a cooling system including a compressor that pumps a mixture of lubricating oil and refrigerant through the filter-type oil separator. The filter type oil separator is configured to receive a first portion of the mixture from the compressor, and a bypass line is configured to bypass a second portion of the mixture around the filter-type oil separator. The bypass line ensures a sufficient amount of oil is present in the compressor.

Systems, methods, and computer-readable mediums are provided for improving the efficiency of a filter-type oil separator in a cooling system including a compressor that pumps a mixture of lubricating oil and refrigerant through the filter-type oil separator. The filter type oil separator is configured to receive a first portion of the mixture from the compressor, and a bypass line is configured to bypass a second portion of the mixture around the filter-type oil separator. The bypass line ensures a sufficient amount of oil is present in the compressor.

A screw compressor (100), comprising a screw rotor (110) and a spool valve (120). The screw rotor (110) comprises a suction head end (111) and an exhaust tail end (112). Gas is sucked in from the suction head end (111) and compressed gas is discharged from the exhaust tail end (112). The spool valve (120) comprises a working side (125) for sealing a compression chamber of the screw rotor (110). The working side (125) comprises a spool valve head end (121) and a spool valve tail end (122) and can do a reciprocating motion along the axis direction of the screw rotor (110). When the spool valve (120) moves to a suction capacity adjusting position (240), the spool valve head end (121) is located at the inner side of the suction head end (111) of the screw rotor (110), and a suction capacity adjusting distance (D2) is formed between the spool valve head end (121) and the suction head end (111) so that the suction capacity of the screw compressor is adjusted. The suction capacity of the screw compressor (100) can be adjusted by means of the spool valve (120), so that the problem of motor temperature and exhaust gas temperature limits of conventional variable frequency screw sets is effectively solved and the operational range and the load regulation ability of the screw compressor are expanded.

Systems, methods, and computer-readable mediums are provided for improving the efficiency of a filter-type oil separator in a cooling system including a compressor that pumps a mixture of lubricating oil and refrigerant through the filter-type oil separator. The filter type oil separator is configured to receive a first portion of the mixture from the compressor, and a bypass line is configured to bypass a second portion of the mixture around the filter-type oil separator. The bypass line ensures a sufficient amount of oil is present in the compressor.