flow switch

A flow switch is an automated control device used to monitor changes in fluid flow (water, gas, oil, etc.) in pipelines and output switch signals. It is widely used in industrial automation, HVAC, refrigeration systems, and other fields. The following is its core information:
1. Working principle and type
Mechanical (baffle/target): The microswitch is triggered by the water flow pushing the baffle, suitable for high viscosity fluids and anti hydraulic impact scenarios.
Thermal type: Based on the principle of fluid taking away heat, with no moving parts, it can detect flow rates as low as 0.1L/min and has a fast response speed.
Differential pressure type: Flow protection is achieved by detecting the pressure difference between the inlet and outlet of the heat exchanger, and supports dual set point control (such as scaling alarm and filter blockage detection).
Turbo type: suitable for cleaning liquids, with an accuracy of ± 1% FS, but it is necessary to avoid particle wear.
2. Technical parameters
Trigger flow threshold: usually 0.75-1L/min (aqueous medium), partially thermal switches can be as low as 0.1L/min.
Working conditions: temperature range of -20~93 ℃, maximum static pressure of 16 bar, output signal of SPDT dry contact (250V).
Protection level: IP54 and above, some models support corrosive environments.
3. Application scenarios
HVAC: Central air conditioning water circulation protection, chiller evaporator/condenser flow monitoring.
Industrial control: Fluid monitoring in petrochemical, power, pharmaceutical and other fields, linked with PLC/DCS systems.
Household equipment: flow detection and dry burn protection for instant electric water heaters and air source heat pumps.

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