Dwyer Series V4

  • 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

Features & Benefits

  • 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
  • Weatherproof, designed to meet NEMA 4
  • Explosion-proof
  • Installs directly and easily into pipeline with a threaded branch connection, tee, or flange
  • 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


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 SAA].

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.

Enclosure Rating: Weatherproof [meets NEMA 4 (IP65)] and Explosion-proof. Listed with UL and CSA for Class I, Groups C and D; Class II, Groups E, F, and G. ATEX CE 0344 EX II 2 G EEx d IIB T6 -20°C≤Tamb≤75°C, EC-Type Certificate No.: KEMA 03ATEX 2383. SAA: Exd C T6 (T amb=60°C), Zone I. Also FM approved.

Switch Type: SPDT snap switch standard, DPDT snap switch optional.

Electrical Rating: UL, FM ATEX and SAA models 10A @ 125/250 VAC. CSA models: 5A @ 125/250 VAC; 5A res., 3A ind. @ 30 VDC . MV option: 1A @125 VAC; 1A res., .5A ind. @ 30 VDC. MT option: 5A @ 125/250 VAC. [MT and MV option not UL, CSA, FM, ATEX or SAA].

Electrical Connections: UL and CSA models: 16 AWG, 6″ (152 mm) long. ATEX and SAA unit: Terminal block.

Conduit Connection: 3/4″ female NPT.

Process Connection: 1-1/2″ male NPT.

Mounting Orientation: Within 5° of vertical for proper operation. Units for horizontal installation (vertical pipe with up flow) available.

Set Point Adjustment: For universal vane: five vane combinations.

Weight: 4 lb 8 oz (1.9 kg).

Agency Approvals: UL, CSA, CE, FM, SAA and ATEX.