DWYER MAGNEHELIC PRESSURE, Dwyer Magnehelic Pressure Gage Inventory #: MISC1744 Dwyer 2030 Differential pressure gage, Range 0-30‘‘ w.c. (inches of water), minor divisions 1.0. 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. The Duel Gage Set Up Is In a NEMA Box with Idec Izumi Power source and Electrical Junction Block