A method for monitoring an oil-injected screw compressor configured to compress aspirated air by returning oil from an oil separator vessel (11) to a compression chamber (12) of a compressor block (30), for condensate formation in the oil circuit due to a too low compression discharge temperature (VET), determines a water inlet mass flow {dot over (m)}.sub.ein(t) and a water outlet mass flow {dot over (m)}.sub.aus(t) for a point in time t and determines generated condensate flow Δ{dot over (m)}.sub.w(t)={dot over (m)}.sub.ein(t)−{dot over (m)}.sub.aus(t) on the basis of difference formation.

A method for monitoring an oil-injected screw compressor configured to compress aspirated air by returning oil from an oil separator vessel (11) to a compression chamber (12) of a compressor block (30), for condensate formation in the oil circuit due to a too low compression discharge temperature (VET), determines a water inlet mass flow {acute over (m)}.sub.ein(t) and a water outlet mass flow {acute over (m)}.sub.aus (t) for a point in time t and determines generated condensate flow Δ{acute over (m)}.sub.w (t)={acute over (m)}.sub.ein(t)−{acute over (m)}.sub.aus (t) on the basis of difference formation.

A simpler notification is given about identifying causes of abnormalities and indicating dealing methods or countermeasures to deal with the causes of abnormalities.

In a gas compressor including: a compressor body that compresses a gas; a drive source that drives the compressor body; at least one physical sensor that is disposed on at least one of a compressed-gas pipe or an electric system and detects a physical quantity in driving of the compressor body; a display unit; and a controller that processes the detected result from the physical sensor and causes the display unit to display information according to the processing, the controller stores in advance the associated relation between a preset range with respect to a rate of change of the physical quantity and information about at least one of a cause of a change in the physical quantity and a dealing method of dealing the cause, calculates a rate of change of the physical quantity on the basis of the detected result from the physical sensor, and causes the display unit to display information about at least one of the cause corresponding to the preset range and the dealing method of dealing with the cause when the calculated rate of change of the physical quantity is determined as falling in the preset range.

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.

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.

Even when abnormal heat generation occurs during operation in a state where the temperature of a compressor is not increased, abnormality cannot be detected. A fluid machine includes a fluid machine body; a motor that drives the fluid machine body; a temperature sensor that measures a temperature of the fluid machine body; and a control unit that controls the fluid machine body. The control unit changes a temperature threshold value based on at least one of a pressure of a fluid discharged by the fluid machine body and a frequency of a voltage input into the motor, and issues a notification when the temperature of the compressor body measured by the temperature sensor exceeds the temperature threshold value.

Methods and systems for detecting and correcting improper operation of a compressor in a refrigeration system and/or an HVAC system include a component level detection and prevention and a system level detection and prevention. The system level detection and prevention can be a backup or a confirmation of the component level detection and prevention. The component level detection and prevention can detect and prevent improper compressor operation within a predetermined time so that the compressor's operation period in an improper direction can be minimized, thereby minimizing wear and damage to the compressor.

This electric compressor includes a compressor which rotates to compress a fluid, a motor which rotatably drives the compressor, and a control unit which controls current supply to the motor using first and second components. An allowable current for first and second components exposed to the same temperature is set to be smaller in the second component than in the first component. The second component is disposed at a place in which cooling capability is greater than that of the first component so that allowable power of the second component at rated use is greater than allowable power of the first component. This electric compressor includes a temperature sensor which detects the temperature of the first component and a calculation unit which outputs an alarm signal when the detected temperature and a current flowing in the first component satisfy a predetermined condition.

A method for monitoring an oil-injected screw compressor configured to compress aspirated air by returning oil from an oil separator vessel (11) to a compression chamber (12) of a compressor block (30), for condensate formation in the oil circuit due to a too low compression discharge temperature (VET), determines a water inlet mass flow {dot over (m)}.sub.ein(t) and a water outlet mass flow {dot over (m)}.sub.aus(t) for a point in time t and determines generated condensate flow {dot over (m)}.sub.w(t)={dot over (m)}.sub.ein(t){dot over (m)}.sub.aus(t) on the basis of difference formation.