How Is a Magnehelic Gauge Used?

A Magnehlic gauge is used to measure fan pressure, blower pressure, air velocity, furnace draft, pressure drop across orifice plates, liquid levels in bubbler systems, pressures in fluidic systems and filter resistance, according to Dwyer Instruments, Inc. These types of gauges are primarily found in commercial and industrial applications with regards to heating, ventilation and air conditioning (HVAC) systems.