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.

Magnehlic gauges feature accuracy to within 2 percent with more than 80 models available. Users can determine low air pressure, corrosive gas pressure and differential very quickly. reveals that the overall use for Magnehlic devices is to measure airflow within systems. These gauges help trained professionals determine whether to increase airflow efficiency in heating and cooling ducts.

Some devices can easily detect airflow movements. Gauges are attached to rubber tubing via a static pressure tip. The other end of the tubing is inserted directly into key areas of ductwork. Air flows out of the duct through a small hole into the tubing and up to the pressure gauge where the air moves a needle across a series of numbers. When readings are properly taken, experts compare the pressure to ratings for that particular system. Readings that are too low indicate something must be done to increase the flow of air within the HVAC system.