1. When to test?
The operating time and equipment conditions of the air conditioning system both affect the system's airflow and ventilation efficiency. Airflow testing is often conducted when: there are increasing complaints about higher operating costs than normal, unpleasant odors appear, abnormal ventilation noise occurs, or a significant pressure difference between the inside and outside of the building creates noticeable issues such as unwanted drafts and difficulty opening doors. Compare the measured fresh air volume and air exchange rate with recommended values. If the measurement results match the recommended values, the system is performing well.
2. Where to test?
Airflow can be measured in several ways: using a thermal anemometer or a micro differential pressure gauge with a Pitot tube probe inside horizontal ducts; or using a dedicated airflow hood at the supply air diffuser or return air vent.
3. How to test?
First, determine the percentage of outdoor air delivered to the room. Due to the influence of duct shape, frictional resistance, branch pipes, dampers, and switching devices on airflow, the air velocity distribution within the duct is uneven. Therefore, when using average wind speed, a technique called logarithmic segmentation is employed. As shown in the diagram, wind speed measurements are taken at different locations within the duct's cross-sectional plane to ensure the most accurate average wind speed data. This average wind speed multiplied by the duct's cross-sectional area yields the airflow.
Another method is to use an airflow hood. This is a quick measurement method that allows direct data readings at a given location, such as an air outlet. Airflow hoods also play a significant role in balancing air conditioning systems to ensure a predetermined airflow to each area and to create and maintain a suitable pressure differential.
Suzhou Pharma Machinery Co.,Ltd.
2026/01/26
Icey
