- What is it?

The measurement of fan-system performance. A measure of flow rate and pressure at a stated density and fan speed. Flow is typically stated as cfm (cubic feet per minute), pressure as in. wg (inches water gauge).

- Why test a fan-system?

No two fan-systems are alike. Fan performance ratings are developed from laboratory tests. However, add the duct work, elbows, transitions, filters, dampers, etc., and the system becomes unique. On-site testing is requied to assure that the system performance meets the design specifications. Performance results are used as the basis for modifications or adjustments to the system.