Fanning innovation in the HVLS industry

Per AMCA 230-99, the fan is hung on a load cell that converts the force created by the fan into a measurable electrical signal. Placing the fan an adequate distance from the floor, ceiling, walls, and any other obstructions is critical so they do not interfere with the fan’s airflow. With the fan running at full speed, the following are tested:

• Humidity (wet bulb temperature);
• Temperature (dry bulb temperature);
• Thrust (the difference between the fan’s hanging weight, and its weights while running); and
• Air pressure.

The density of the air is calculated from the temperature, humidity, and air pressure, with the information plugged into AMCA’s 230-99 equation for calculating the airflow rate (CFM) which is:

Where:

Q: airflow rate;
A: circular area of the fan (diameter);
F: thrust (i.e. difference between hanging weight and weight while running); and
P:  density of the air.

Unfortunately the ‘2’ in the above equation should not be there—it was included based on an incorrect assumption of how air flows through the fan. Calculating the airflow rate with this equation generated inflated numbers.

For a few years, AMCA completely removed the cfm calculation and measuring only thrust. In 2012, AMCA reintroduced it, this time using the correct formula in its 230-12 standard:

AMCA 230-12 not only corrected the formula, but also introduced an efficiency metric to explain how the fans use electrical energy. This is calculated by taking the existing cfm formula and dividing it by the power used:

Unfortunately, AMCA 230-12 is limited to fans less than 1.8 m (6 ft)
in diameter, leaving high-volume, low-speed (HVLS) fan manufacturers without standards or guidelines to measure airflow.

In 2015, AMCA expanded the scope of its standard to include fans up to 7.3 m (24 ft) in diameter. Additionally, the U.S. Department of Energy (DOE) adopted AMCA 230-15, which means all upcoming power usage and efficiency requirements will be based on this standard.