Filter
Top Products
TRG-TRC013-EN 9
period one
Fan Performance
notes
The characteristics of a fan’s performance under various duct pressure
conditions is tested by an apparatus similar to the one shown here.
The fan is connected to a long piece of straight duct with a throttling device at
the end. The throttling device is used to change the air resistance of the duct.
The fan is operated at a single speed and the power applied to the fan shaft is
measured by a device called a dynamometer. As discussed on the previous
slide, a single manometer is used to measure the velocity pressure—the
difference between the total and static pressures.
The test is first conducted with the throttling device removed. This is called
wide-open airflow. With no resistance to airflow, the pressure generated by
the fan is velocity pressure only—the static pressure is negligible.
The throttling device is then put in place and progressively moved toward the
closed position. The pressures are recorded at each throttling device position.
When the throttling device is fully closed, only static pressure is being
generated by the fan because there is no airflow. This point is called the
blocked-tight static pressure.
Fan Performance Test
dynamometer
dynamometer
air
air
straightener
straightener
manometer
manometer
throttling
throttling
device
device
fan
fan
Figure 14