One of the ways to assure that a customer’s case is performing as it should is to test the airflow. One of the best ways to do this is with a test instrument that measures feet per minute as illustrated.
Be sure to measure the airflow at the case discharge air outlet as illustrated below:
The manufacturer recommends that the best time to measure the case airflow is during the warmest time during defrost as the case cycle is terminating.
Below is a manufacturers chart detailing an example of a case specifications including the case design average air flow. Without the proper air flow, the case temperature will not reach the desired set point and the product integrity will suffer.