... protection of some refrigeration systems, residential, commercial system.The pressure control is used for the high and low pressure protection of ... ~ 700PSI), low (3 ~ 145PSI), vacuum (-7.4 ~ 0PSI)3. Electrical control method: SPST (two wires), SPDT (three wires)4. Fitting structure ... 15+/-15MPS350High Pressure350- -+/-15+/-15MPS450Manual Reset450- -+/-15+/-15 heat pump air compressor pressure switch