Magnehelic Differential Pressure Gage 0-25 mm w.c.

Specifications (PDF)

Select the Magnehelic® gage for high accuracy–guaranteed within 2% of full scale
and for the wide choice of 81 models 
available to suit your needs precisely. Using Dwyer’s simple, frictionless Magnehelic®
gage movement, it quickly 
indicates low air or non-corrosive gas pressures–either positive, negative (vacuum) or 
differential. The design resists 
shock, vibration and over-pressures. No manometer fluid to evaporate, freeze or cause 
toxic or leveling problems. 
It’s inexpensive, too.

The Magnehelic® gage is the industry standard to measure fan and blower pressures, 
filter resistance, air velocity, 
furnace draft, pressure drop across orifice plates, liquid levels with bubbler systems and 
pressures in fluid amplifier or fluidic systems. It also checks gas-air ratio controls and 
automatic valves, and monitors blood and respiratory 
pressures in medical care equipment.

Note: May be used with Hydrogen. Order a Buna-N diaphragm.
Pressures must be less than 35 psi.

Product Specifications

Service: Air and non-combustible, compatible gases. (Natural Gas option available.) Wetted Materials: Consult factory. Housing: Die cast aluminum case and bezel, with acrylic cover, Exterior finish is coated gray to withstand 168 hour salt spray corrosion test. Accuracy: ±2% of full scale (±3% on -0, -100PA, -125PA, -10MM and ±4% on -00, -60PA, -6MM ranges), throughout range at 70°F (21.1°C). Pressure Limits: -20″ Hg. to 15 psig.† (-0.677 bar to 1.034 bar); MP option; 35 psig (2.41 bar), HP option; 80 psig (5.52 bar). Overpressure: Relief plug opens at approximately 25 psig (1.72 bar), standard gages only. See Overpressure Protection note on Catalog page. Temperature Limits: 20 to 140°F.* (-6.67 to 60°C). Mounting Orientation: Diaphragm in vertical position. Consult factory for other position orientations. Process Connections: 1/8″ female NPT duplicate high and low pressure taps – one pair side and one pair back. Weight: 1 lb 2 oz (510 g); MP & HP 2 lb 2 oz (963 g). Standard Accessories: Two 1/8″ NPT plugs for duplicate pressure taps, two 1/8″ pipe thread to rubber tubing adapters and three flush mounting adapterswith screws. (Mounting and snap ring retainer substituted for 3 adapters in MP & HP gage accessories.) †For applications with high cycle rate within gage total pressure rating, next higher rating is recommended. See Options Page. *Low temperature models available as special option.

Product Features

• Bezel provides flange for flush mounting in panel. • Clear plastic face is highly resistant to breakage. Provides undistorted viewing of pointer and scale. • Precision litho-printed scale is accurate and easy to read. • Red tipped pointer of heat treated aluminum tubing is easy to see. It is rigidly mounted on the helix shaft. • Pointer stops of molded rubber prevent pointer over-travel without damage. • “Wishbone” assembly provides mounting for helix, helix bearings and pointer shaft. • Jeweled bearings are shock-resistant mounted; provide virtually friction-free motion for helix. Motion damped with high viscosity silicone fluid. • Zero adjustment screw is conveniently located in the plastic cover, and is accessible without removing the cover. O-ring seal provides pressure tightness. • Helix is precision made from an alloy of high magnetic permeability. Mounted in jeweled bearings, it turns freely, following the magnetic field to move the pointer across the scale. • Samarium Cobalt magnet mounted at one end of range spring rotates helix without mechanical linkages. • Calibrated range spring is flat spring steel. Small amplitude of motion assures consistency and long life. It reacts to pressure on diaphragm. Live length adjustable for calibration. • Silicone rubber diaphragm with integrally molded O-ring is supported by front and rear plates. It is locked and sealed in position with a sealing plate and retaining ring. Diaphragm motion is restricted to prevent damage due to overpressures. • Die cast aluminum case is precision made and iridite-dipped to withstand 168 hour salt spray corrosion test. Exterior finished in baked dark gray hammerloid. One case size is used for all standard pressure options, and for both surface and flush mounting. • Blowout plug of silicone rubber protects against overpressure on 15 psig rated models. Opens at approximately 25 psig. • O-ring seal for cover assures pressure integrity of case.

Applications
	• Filter Monitoring • Air Velocity with Dwyer Pitot Tube • Blower Vacuum Monitoring • Fan Pressure Indication • Duct, Room or Building Pressures • Clean Room Positive Pressure Indication