Fan manufacturers usually provide regulating air doors as necessary equipment. However, in many systems, the air volume control regulating air door is located in or near the fan outlet. Air volume control and regulating air doors are generally made of opposite or parallel blades. When the regulating valve part is closed, the parallel vane regulating air damper can divert the air flow to one side of the pipeline. This will produce uneven velocity distribution at the regulating air gate, and the air flow near the downstream bypass line will be seriously affected.
The blade of the regulating air door installed by the centrifugal fan should be perpendicular to the fan shaft, so as to ensure the best air performance.
The pressure loss of the regulating air door depends on the uniform intake velocity distribution. If the regulating air door is installed close to the outlet of the fan, then the intake velocity distribution will be uneven, and the pressure loss of the air door will be increased by adjusting the pressure loss of the air door.www.jnblower.com