Use a Damper to Add Resistance and Reduce Airflow
If you want to reduce a fan’s air volume and horsepower without adjusting speed, then you can use a damper to add system resistance. The damper can be installed on either the inlet or outlet side of the fan, and you can determine the best location based on your specific application and your fan performance curve. More often than not, we’ll recommend placing the damper at the outlet as the most cost-effective way to simply add resistance.
Recommended: Outlet Damper
Placing an opposed-blade damper at the fan’s outlet is one of the easiest ways to add reduce flow and horsepower. An outlet damper will add resistance without interfering with airflow at the inlet of the fan. The damper can be controlled with a manual arm, or you can opt for an electric or pneumatic actuator with positioners to automate the damper’s opening and closing. It all depends on the needs of your application.
Alternative: Inlet Damper
You can also use a damper on the inlet side, but there are a couple things to consider. An inlet vane damper can be directly mounted to the fan’s inlet, and this design will pre-spin the air to match the impeller’s blade direction. The upfront cost is higher than an outlet damper, but this design will maximize fan performance and provide greater system flexibility for some applications.
Other inlet dampers, such as a butterfly design, may be used. But make sure you place the damper further down the airstream to make sure it doesn’t interfere with the air direction as it enters the fan.
Hear from an Application Engineer About using a Damper to Add Resistance
Chet White, Senior Application Engineer / Sales & Marketing Manager, illustrates how to use a damper in this 2-minute whiteboard video.
To ask questions, get more details, or discuss your application, reach out and connect with one of our application engineers.
Can’t get enough? Several additional posts might interest you as you think about air resistance, dampers, and fan performance.
- Choices, Choices: Control Fan with VFD or Damper?
- Inlet Vane Dampers Give Industrial Process Air a Running Start
- Why Go With the Flow? Take Control