How to Calculate the Air Flow & the Static Pressure Drop Through the Grill

Air flows continuously through a system's vents.
••• Jupiterimages/Photos.com/Getty Images

Building owners must monitor the flow through air duct grills to test how well their ventilation systems work. A pilot tube assembly, a device containing multiple probes, measures the static pressure drop between the grill’s two sides. The air flow rate through the grill is proportional to this pressure and is related to the grill’s size. If these values turn out far less than you expect them to be, this implies a fault in your system such as an unexpected break in a conduit.

    Hold the pilot tube assembly’s static pressure probe at a right angle to the air flow.

    Hold the assembly’s total pressure probe parallel to the air flow.

    Read the assembly’s pressure gauge, which states the static pressure drop across the grill in inches of water.

    Find the square root of the static pressure. For example, if the pressure drop is 1.3 inches of water: √1.3 = 1.14.

    Multiply this answer by the grill’s area, measured in square feet. For example, if the grill measures 2.2 square feet in area: 1.14 × 2.2 = 2.5.

    Multiply the result by 4,005, a conversion constant: 2.5 × 4,005 = 10,012, or just over 10,000. This is the air flow through the grill, measured in cubic feet per minute.

Related Articles

How to Calculate Static Head
How to Calculate Evaporator Sizing
How to Convert CV to GPM
How to Convert mm Hg to in Hg
How to Calculate Potential Difference
How to Convert KPa to Liters Per Minute
How to Convert Kilopascals to Joules
How to Test a Diode Rectifier
How to Design an RC Snubber
How to Calculate GPM From Differential Pressure
How to Calculate Flow Rate With Pipe Size and Pressure
How to Calculate Ohms
How to Calculate the Size of a Grounding Conductor
How to Test ESD Mats
How to Calculate Condensate Flow From AC Units
How to Convert HVAC Tons to Amps
How to Calculate the Square Meters in a Triangle
How to Find a Short in a Circuit Board
How to Convert kPa to kN/m
How to Calculate GPM from PSI for Water

Dont Go!

We Have More Great Sciencing Articles!