Series H3 Explosion-Proof Differential Pressure Switches

Setpoints from 10" w.c. to 200 psid – Rated 1500 psig, Weatherproof

Explosion-proof Series H3 Explosion-Proof Differential Pressure Switch, heavy duty, 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 deadbands approximately 5% of range, with zero setpoint shift due to variation in working pressures. Friction is minimized and repeatability increased by allowing range spring to act directly on diaphragm plate. Rolling diaphragm design maintains constant effective area to further reduce friction. Diaphragm is allowed to “seat”, allowing application of full rated pressure, up to 1500 psi (103 bar), on either high or low pressure port, without damage. Special over-travel feature prevents overtightening of range adjust screw.

Choose optional 316SS chamber for water and water-based fluids or harsher applications.

Product Applications

  • 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.

Models & Ordering

Shipping Information

All shipping times are dependent on product availability at time of shipment.

Although we make every effort to ensure a continuous supply of our products, occasional circumstances may force us to temporarily run out of a product, or have shipping delays. Should this occur, customers will be notified soon after placement of any orders for such products and, if applicable, items will be put on backorder. For orders requiring expedited shipment, our customer service team can be contacted to confirm product availability

Build Your Custom Part. Use our Product Configurator


Wetted Materials:
See Ordering page.
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:
Set Point Adjustment:
Internal screw.
4 lb 2 oz (2 kg).
Approximately 5% of range.
Agency Approvals:
ATEX (see "Ratings Chart" on catalog page), CE, CSA, UL.


  • 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


Model Number Description Usually Ships* Price Order
Pipe mounting kit for 1-1/4 A-610 Pipe mounting kit for 1-1/4" to 2" pipe. 5.6" x 4.6" x 1.4", 1.0 .lb (Magnehelic® sold separately) Same Day $35.50 Order


Model Chart

EXAMPLE H3 A 1 S C MV Series H3A-1SC-MV Explosion-proof, Weatherproof Differential Pressure Switch, aluminum chamber, nitrile diaphragm, range 10-180" w.c., SPDT snap switch, terminal block, ATEX approved, with gold contacts on snap switch.
SERIES H3           Explosion-proof, Weatherproof Differential Pressure Switch
        Aluminum Chamber and Nitrile Diaphragm
Stainless Steel Chamber and Fluoroelastomer Diaphragm
      10-180" w.c. (2.48-44.78 kPa)
0.5-15 psid (0.03-1 bar)
5-70 psid (0.34-4.8 bar)
10-200 psid (0.7-13.8 bar)
SWITCH       S
    SPDT Snap Switch, Rated 5 A @ 120/250 VAC, 30 VDC
DPDT Snap Switch, Rated 5 A @ 120/250 VAC, 30 VDC
  ATEX Approved Internal Terminal Block
18 AWG x 18" Lead Wires
UL/CSA Approved Internal Terminal Block
Housing with Drain, allows condensate to be drained, (NEMA 3 instead of 4X)
Gold Contacts on Snap Switch for Dry Circuits
Stainless Steel Tag
Fluoroelastomer Diaphragm (standard with stainless steel chamber)




For which pressure switch applications are gold contacts recommended?
For "dry circuit" applications where little or no current is flowing in the circuit to help burn off contact dirt and oxidation. Switches used with solid state circuits often fall in this category.

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