Air Velocity Measurement Test is done to find out the velocity of air coming out and also the air flow rate. The number of air changes per hour in the clean room / clean zone can be calculated.

The velocity is recorded at several places of the Hepa filter and the average velocity, minimum and maximum velocities are recorded. The cross sectional surface area open to air flow is measured and multiplied with the average velocity to give the average air flow rate.

The equipment anemometer is used for this purpose.. They can be of two types – vane type or hot wire type.