Discrepancy between Differential Pressure Switch and Sensor
Differential pressure switch is mainly used for equipment system fault alarm with differential pressure, because only one switch value can be read, rather than analog quantity 4-20mA can be transmitted by transmitter or sensor
For example, when the pressure difference of the filter screen of the air conditioning fresh air unit exceeds a certain value, the pressure difference switch acts, and the system alarms, you will be reminded that you need to clean the filter screen
For another example, there are many differential pressure switches on centrifugal pumps. If the differential pressure is lower than a certain value, an alarm is required to prevent cavitation of the pump impeller. The function of the pressure transmitter is mainly to control. The read-out data is input into the control system through integral conversion for control. The differential pressure sensor is generally installed in the air supply pipe
The difference between the differential pressure switch and the differential pressure transmitter can also be understood as follows: the differential pressure sensor can continuously output the electrical signal, and according to the size of the electrical signal, the secondary instrument can display the real-time change of the differential pressure. The differential pressure switch is only a switch, which is used for system fault alarm. When it is higher than its set point, the differential pressure switch will act, and when it is lower than the set point, it will not act.
In short, the so-called water pressure difference switch is to get accurate flow through the pressure drop of water flow at both ends of the valve and orifice plate, and then through the detection of the pressure drop and flow curve of the valve or orifice plate. The specific principle of the differential pressure switch is: the application of the differential pressure switch in the HVAC system is mainly controlled according to the resistance and flow curve of the HVAC equipment. The water side heat exchanger (sleeve type, shell and tube type, tube plate type and commonly used plate type heat exchanger), water filter, valve and water pump in the HVAC system are There is a performance curve of pressure drop and flow. As long as the measured pressure difference on both sides of the differential pressure switch is compared with the preset value, the flow can be accurately controlled.
Difference between differential pressure switch and differential pressure sensor: differential pressure sensor can continuously output electric signal, and it can display the change of differential pressure in real time through two instruments according to the size of electric signal. The differential pressure switch is only a switch, which is used for system fault alarm. When it is higher than its set point, the differential pressure switch will act, and when it is lower than the set point, it will not act.