Systems and methods of the invention relate to diagnosing a compressor. A method may include monitoring a pressure of compressed air within a reservoir, actuating a piston within a cylinder of the compressor, and detecting a leak condition of an exhaust valve of the cylinder through recognition of a change in the monitored pressure of the compressed air within the reservoir during a time period in which the piston is actuated. A system is also disclosed including an engine, a compressor operatively connected to the engine, and a controller that is operable to determine a condition of the compressor.

A membrane pump usage condition detection system and a method of determining a membrane pump usage condition. The membrane pump usage condition detection system comprises a membrane pump defining a flow path arranged to be opened and closed by at least one valve, a measuring device; a comparator; and a signal generator. The measuring device is configured to determine an electrical characteristic between two points on the flow path of the membrane pump, one point arranged upstream of the at least one valve and the other point arranged downstream of the at least one valve. The measuring device measures the electrical characteristic when the at least one valve is closed. The comparator is configured to monitor the electrical characteristic. The signal generator is arranged to provide an output signal when the electrical characteristic is indicative of a membrane pump usage condition.

A liquid feeding device includes a primary plunger pump; a secondary plunger pump connected downstream; a check valve provided between the primary plunger pump and the secondary plunger pump; a primary pressure sensor that detects a pressure in the pump chamber of the primary plunger pump; a liquid feeding control part configured to control operations of the primary plunger pump and the secondary plunger pump; and a liquid leakage detector configured to detect liquid leakage in the check valve based on a change in an output value of the primary pressure sensor during the waiting time. The liquid feeding control part is configured to control the operation of the primary plunger pump so that a waiting time, where the primary plunger pump stops without operating, is present while a discharge operation by the secondary plunger pump is performed after a suction by the primary plunger pump is completed.

A membrane pump usage condition detection system and a method of determining a membrane pump usage condition. The membrane pump usage condition detection system comprises a membrane pump defining a flow path arranged to be opened and closed by at least one valve, a measuring device; a comparator; and a signal generator. The measuring device is configured to determine an electrical characteristic between two points on the flow path of the membrane pump, one point arranged upstream of the at least one valve and the other point arranged downstream of the at least one valve. The measuring device measures the electrical characteristic when the at least one valve is closed. The comparator is configured to monitor the electrical characteristic. The signal generator is arranged to provide an output signal when the electrical characteristic is indicative of a membrane pump usage condition.

Systems and methods of the invention relate to diagnosing a compressor. A method may include monitoring a pressure of compressed air within a reservoir of a compressor, actuating an unloader valve of the compressor, and detecting a leak condition of the compressor through recognition of a change in the monitored pressure of the compressed air within the reservoir during a time period in which the unloader valve is actuated. A system is also disclosed including an engine, a compressor operatively connected to the engine, and a controller that is operable to determine a condition of the compressor.

Systems and methods of the invention relate to diagnosing a compressor. A method may include operating a compressor to compress air from a first stage compressor into an intermediate stage reservoir, to deliver air from the intermediate stage reservoir to a second stage compressor, and to further compress the air in the second stage compressor into a primary reservoir, monitoring an intermediate stage pressure of the intermediate stage reservoir, and identifying a condition of the compressor through recognition of a change in the monitored intermediate stage pressure during a time period in which the compressor is operated. A vehicle system is also provided including an engine, a compressor operatively connected to the engine, and a controller that is operable to identify a condition of the compressor.

A diaphragm pump converts rotation of a motor into a reciprocating motion and drives a diaphragm. The diaphragm pump includes a partition configured to form a pump chamber together with a deformation portion of the diaphragm, a suction passage communicating with the pump chamber via a suction through hole extending through the partition, and a suction valve configured to open/close the suction passage. The valve body of the suction valve includes a leak structure configured to form a channel between the valve body and the seat surface of the partition.

A medical fluid pumping system includes a medical fluid pump for pumping a process fluid and a medical fluid chassis operable with the medical fluid pump. The medical fluid pump includes a first pump chamber, a first inlet valve chamber including a first inlet valve diaphragm, a first outlet valve chamber, a second pump chamber, a second inlet valve chamber including a second inlet valve diaphragm, and a second outlet valve chamber. The medical fluid chassis includes a motive fluid source providing motive fluid at a motive fluid pressure. The first and second inlet valve diaphragms are configured to actuate from an open to a closed position at a pressure less than the motive fluid pressure to mitigate process fluid backflow through the first and second inlet valves.

A membrane pump usage condition detection system and a method of determining a membrane pump usage condition. The membrane pump usage condition detection system comprises a membrane pump defining a flow path arranged to be opened and dosed by at least one valve, a measuring device; a comparator; and a signal generator. The measuring device is configured to determine an electrical characteristic between two points on the flow path of the membrane pump, one point arranged upstream of the at least one valve and the other point arranged downstream of the at least one valve. The measuring device measures the electrical characteristic when the at least one valve is closed. The comparator is configured to monitor the electrical characteristic. The signal generator is arranged to provide an output signal when the electrical characteristic is indicative of a membrane pump usage condition.