Dwyer Series V4 Flotect® Vane-Operated Flow Switch
Dwyer Series V4 Flotect® Vane-Operated Flow Switch

Dwyer Series V4 Flotect® Vane-Operated Flow Switch

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Flow includes Flow Transmitters, Flow Sensors, Flowmeters, Sight Flow Indicators and Water Meters. Mass Flowmeters, Controllers, Flow Indicators and Controllers are ideal for measurement of flow rates. Flow Switches come as paddle, thermal, piezo, and shuttle/piston. Flow Switch Sensors with an electrical contact output at a specific flow rate have different types of switches, which are paddle, thermal, piezo, and shuttle/piston.

Paddle flow switches or vane sensors with an electrical contact output are at a specific flow rate. Dwyer flow switches are economical and reliable. Applications include proof of boiler flow, air conditioning, controlling of dampers according to flow, and protecting pumps, motors and other equipment against low or no flow.

The Series V4 Flotect® Flow Switches are rugged and reliable, ideal for automatically protecting equipment and pipeline systems against damage from reduction or loss of flow. Time tested in thousands of pipeline installations and processing plants around the world this Series is Weatherproof, designed to meet NEMA 4 and Explosion-proof (listing included in specifications). This series can be used in pipes 1-1/2″ (38.10 mm) and up.


  • Leak proof body machined from bar stock
  • Choice of custom vane calibrated for your application, Model V4, or field adjustable multilayer vane, Model V4-2-U (see set point chart)
  • Installs directly and easily into pipeline with a threadolet, tee, or flange (see application drawings)
  • Can be used in pipes 1-1/2″ and up
  • Electrical assembly can be easily replaced without removing the unit from installation so that the process does not have to be shut down
  • High pressure rating of 1000 psig (69 bar) with the brass body and 2000 psig (138 bar) with the 316 SS body
  • Unique magnetically actuated switching design gives superior performance
  • Features a free-swinging vane which attracts a magnet within the solid metal switch body, actuating a snap switch by means of a simple lever arm with no bellows, springs, or seals to fail


  • Protects pumps, motors and other equipment against low or no flow
  • Controls sequential operation of pumps
  • Automatically starts auxiliary pumps and engines
  • Stops liquid cooled engines, machines and processing when coolant flow is interrupted
  • Shuts down burner when air flow through heating coil fails
  • Controls dampers according to flow
  • Another Article:


Service Gases or liquids compatible with wetted materials.
Wetted Materials Vane: 316 SS; Body: Brass or 316 SS standard; Magnet Keeper: 430 SS standard, 316 SS optional; Options: Other materials also available, consult factory (e.g. PVC, Hastelloy, Nickel, Monel, Titanium).
Temperature Limit -4 to 275°F (-20 to 135°C) standard, MT high temperature option 400°F (205°C) [MT option not UL, CSA, ATEX or IECEx] ATEX and IECEx options, ambient temperature -4 to 163°F (-20 to 73°C); Process temperature -4 to 163°F (-20 to 73°C).
Pressure Limit Brass body 1000 psig (69 bar), 316 SS body 2000 psig (138 bar), optional 5000 psig (345 bar) available with 316 SS body and SPDT switch only.
Switch Type SPDT snap switch standard, DPDT snap switch optional.
Process Connection 1-1/2″ male NPT or 1-1/2″ male BSPT or 38.10 mm.
Set Point Adjustment: For universal vane: five vane combinations.
Weight 4 lb 8 oz (1.9 kg).
Agency Approvals ATEX, CE, CSA, FM, IECEx, UL

Download Data Sheet: Series V4 Flotect® Vane-Operated Flow Switch

Ref: dwyer-inst.com

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