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Fan Performance Test
throttling device
fan
dynamometermanometer
air straightener
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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
The test is first conducted with the throttling device removed. This is called
. With no resistance to airflow, the pressure generated by the fan is velocity pressure
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
.
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