Dwyer H3 Explosion-Proof Differential Pressure Switches

Dwyer H3 Explosion-Proof Differential Pressure Switches, heavy-duty, the industrial unit has a unique new design which provides sensitivity to differential pressures as low as 10 inches of water (254 mm w.c.), yet handles total pressure of 1500 psi (103 bar). Unlike common differential pressure switches that use a piston-type motion transfer, the Series H3 utilizes a rotary motion transfer shaft that prevents a change in total pressure from causing a setpoint shift.

Unit yields dead bands approximately 5% of range, with zero setpoint shift due to variation in working pressures. Friction is minimized and repeatability increased by allowing the range spring to act directly on the diaphragm plate. The rolling diaphragm design maintains a constant effective area to further reduce friction. The diaphragm is allowed to “seat”, allowing application of full rated pressure, up to 1500 psi (103 bar), on the either high or low-pressure port, without damage. The special over-travel feature prevents overtightening of range adjust screw.

Dwyer H3 Explosion-Proof Differential Features

  • Rotary motion design prevents set point shifts
  • Explosion-proof housing for use in applications where protection of process and personnel is needed
  • Option for use with water and water-based solution makes this a versatile switch


  • Water flow proving with an orifice plate.
  • Differential pressure across chiller.
  • Liquid filter status.
  • Perfect for monitoring differential water pressure on filters, chiller coils, and flow elements.

Another Article:

Dwyer H3 Explosion-Proof Differential Specification

Temperature Limit -4 to 220°F (-20 to 104°C). ATEX: -4 to 194°F (-20 to 90°C).
Pressure Limit 1500 psig (103 bar).
Enclosure Rating Standard meets NEMA 4X (IP56); Drain option meets NEMA 3 (IP54). For hazardous use see “Hazardous Location Ratings Chart” on Catalog page.
Switch Type SPDT or DPDT snap switch.
Electrical Rating 5 A @ 125/250 VAC, 30 VDC.
Electrical Connections See Ordering page.
Conduit Connection 3/4″ female NPT.
Process Connection 1/8″ female NPT.
Mounting Orientation Vertical.
Set Point Adjustment Internal screw.
Weight 4 lb 2 oz (2 kg).
Dead band Approximately 5% of range.
Agency Approvals ATEX (see “Ratings Chart” on catalog page), CE, CSA, UL.

Download Data Sheet: Series H3 Explosion-Proof Differential Pressure Switches

Ref: dwyer-inst.com

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