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This post was last edited by zhengpeichun on 2018-7-14 09:18 at http://yunrun.com.cn/upload/201807/11/201807112356030163.png. Based on the actual conditions of pressure switch use in the field, common failure symptoms, causes of failures, and solutions for pressure switches are outlined here for reference by instrument technicians. Symptoms of pressure switch failure, causes of pressure switch failure, methods for dealing with pressure switch failures: No output signal from the pressure switch; damaged microswitch – replace the microswitch; the switch’s setting value is too high – adjust it to an appropriate value; wires connected to the microswitch are not properly connected – reconnect them to ensure reliable contact; the pressure sensing element is poorly assembled and stuck – reassemble it to ensure proper operation; poor sensitivity of the pressure switch; excessive friction in the transmission mechanism such as rods or pistons – reassemble it to improve sensitivity; the contact travel of the microswitch is too long – adjust the travel of the microswitch; adjustment screws and rods are not set correctly – adjust their positions; the pressure switch is installed unevenly or at an angle – reinstall it vertically or horizontally; the pressure switch sends signals too quickly; the damping holes at the oil inlet are too large – reduce the size of these holes or install a damper on the measurement pipeline; the isolation diaphragm is broken – replace the isolation diaphragm; excessive fluctuations or shocks in system pressure – install a damper on the measurement pipeline. A pressure switch is a device that combines with electrical switches; when the predetermined fluid pressure is reached, the switch contacts activate. It is primarily used in industrial equipment in sectors such as power plants, petrochemicals, and metallurgy to generate alarm or control signals, and it plays an important role in the industrial field by preventing damage to critical devices during production processes and avoiding serious production accidents. Pressure switches yunrun.com.cn/tech/2075.html Terms related to pressure switches ◆ Precision: A value that indicates the accuracy of a device, including factors such as linearity, tolerance, hysteresis, and repeatability. ◆ Maximum pressure: The highest value within the pressure range. ◆ Full scale: The difference between the maximum and minimum values of the pressure range. ◆ On-off difference (dead zone): refers to the difference between the set operating value and the reset value of a switch; for example, if the set value is 1 MPa and the actual reset value is 0.9 MPa, then the on-off difference is 0.1 MPa. ◆ Operating temperature: refers to the temperature range within which the internal components and sensitive elements of the instrument do not undergo persistent deformation during operation. The recommended operating temperature range for standard pressure switches is -5 to 400°C. If the temperature of the medium is too high, a siphon tube can be used as an accessory to help reduce the temperature. ◆ SPDT: Composed of one normally open contact, one normally closed contact, and a common terminal. ◆ Double-pole double-throw: It consists of a symmetrical left and right common terminal, along with two sets of normally open and normally closed terminals. ◆ Upper limit alarm: When the pressure rises to the set value, the contact activates and the circuit is closed. ◆ Lower limit alarm: When the pressure drops to the set value, the contact activates and the circuit is closed. ◆ Pressure rating: The maximum pressure that a pressure switch can withstand while maintaining its normal performance. However, when a pressure switch is used in overpressure applications, the sensitive element will undergo continuous deformation, causing the pressure setting to change; as a result, the pressure switch will be unable to function properly and may even get damaged. ◆ IP (Protection Rating): It is a standard established by the International Electrotechnical Commission (IEC) that deals with the dust and moisture resistance of lighting fixtures.