Read the axes and test conditions
Find the airflow axis, pressure axis and units before comparing points. Check whether the curve uses static or total pressure and whether it applies to a particular speed, wheel size or air condition.
Keep the model reference with the graph. Two curves that look similar may describe different equipment or testing conditions. The fan-type comparison explains why the product category alone is insufficient.
Locate the proposed duty
- Take the required airflow from the approved design information.
- Find the corresponding required pressure for the complete route.
- Mark their intersection on the appropriate curve.
- Check the manufacturer’s permitted operating region and motor requirements.
The operating point depends on the connected system as well as the fan. A quoted maximum airflow at little resistance is not a substitute for this check.
Compare like with like
| Item | Confirm |
|---|---|
| Airflow | Same units and required operating condition. |
| Pressure | Same pressure basis and system boundary. |
| Speed | Specified speed or controller setting. |
| Installation | Inlet and outlet conditions match the design assumptions. |
| Power | Motor and electrical requirements suit the selection. |
Our pressure-drop guide helps establish the boundary before you compare curves.
Keep the graph with the handover record
Retain the selected curve, design duty and final equipment details together. Record changes to the duct route or control arrangement so the original selection remains understandable.
If a later alteration adds resistance, the fan’s operating point can change. Have the design reviewed before increasing speed or replacing a component. Use the Fumeflow selection guide to prepare a clear enquiry about an existing or proposed installation.