Flow
Flow Switches
No-flow and low-flow switches to protect pumps, compressors and heat exchangers.
Flow switches confirm that a fluid is moving and raise an alarm or trip when it isn’t: protecting pumps from running dry, compressors and heat exchangers from loss of cooling water, and burners from loss of combustion air.
Choosing a flow switch
- Thermal dispersion (FCI, Dwyer TDFS2): no moving parts to foul, wear or stick, so they suit dirty liquids, low velocities, gases and large pipes. The FCI FLT93 is a heavy-duty process switch; the FS10A watches the small flows in analyser sample lines.
- Paddle and vane switches (DwyerOmega, SOR 1520): economical and simple for clean liquids, such as the Dwyer FS2 on boilers and heaters.
- Magnetic piston switches (Dwyer Flotect V4 and V6): low-flow protection in weatherproof or explosion-proof housings.
Some thermal switches also give a temperature alarm from the same probe. Where you need the actual flow rate, see flow meters.
What to tell us
- The fluid (liquid or gas) and whether it is clean or dirty
- The pipe size and the flow at which the switch should trip
- Operating pressure and temperature
- Contact rating and supply voltage
- Area classification and approvals
Every switch is built to order to these details. See flow switches placed on chiller plants, pumps and compressors, cooling towers, liquid-cooled server rooms and steam and power boilers.
