# SOP for Measurement of Airflow Velocity and Air Changes per Hour

OBJECTIVE
To lay down the procedure for the measurement of airflow velocity and air changes per hour (ACPH)

SCOPE
Procedure applies to the Air Handling Unit located in XYZ Limited.

RESPONSIBILITY
Officer/Executive Engineering: Shall be responsible for the measurement of airflow velocity and air changers per hour
Manager-Engineering: To ensure that the procedure is properly followed

PROCEDURE
• Ensure that Air Handling Units are ON.
• Scan the area of the HEPA Filter, with the anemometer probe, 6 inches from the filter face.
• For the case of the experiment, divide the area of the HEPA Filter into four equal, hypothetical grids.
• Record the velocity readings taken at the center of the grids, and at the junction of dividing lines (center of HEPA Filter).
• Calculate the Average Velocity (V in feet per minute) as:

V1 = Velocity observation at each point
• Measure the dimensions of each air inlet i.e. HEPA Filter, in feet and record it.
• Calculate the Area (A in square feet) of each Air inlet as a product of the length and the width as
A = L  x  W

Where,
L = length of inlet
W = width of inlet
• Calculate the Total Air Volume (T in cubic feet per minute) supplied in each zone, by using the formula :
T = A x V
Where
A = Area of particular Air inlet in square feet
V = Average air velocity at particular air inlet in feet per minute
• Calculate the total volume of the room by multiplying the length of the room, the breath of the room and height of the room.
Volume = L x B x H
• Total air change is divided by the total volume of the room will give the air change per hour. Fill the record in the form.

ABBREVIATIONS
SOPs : Standard operating procedures
No. : Number.
HEPA Filter: High Efficiency Particulate Air Filter
ACPH: Air Changes Per Hour

ATTACHMENTS
Attachments 1: Velocity & ACPH Test Report

REVISION HISTORY
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