Knowing how to set up proper fan curves is essential for reliable engineering of industrial and mining ventilation systems. A proper fan curve is not drawn by guesswork; it is based on tested performance data from the manufacturer, correctly adjusted for your site conditions and linked to the system curve of your ducts or mine airways.
The process starts with accurate fan test data. Fan manufacturers test each model on standardized test rigs to measure airflow, pressure, power and efficiency at different operating points. These results are used to generate fan curves at specific speeds for standard air (typically 1.2 kg/m³ at sea level). To set up proper curves for your project, obtain these certified performance curves and verify that they cover the range of flows and pressures you expect to use.
Next, you must apply corrections for air density and speed. If your site is at high altitude, experiences high temperatures, or handles different gas mixtures, the air density can differ significantly from standard conditions. Using the fan laws, you adjust pressure and power in proportion to density and adjust the curve for any planned speed changes, such as variable-frequency drive operation. This gives you a realistic curve that reflects how the fan will behave in your plant or mine, not just in the test lab.
Once the corrected fan curve is ready, you need to construct the system curve. The system curve represents how much pressure is required to achieve each possible airflow through your ducts, filters, scrubbers, cooling coils, regulators or mine roadways. Engineers calculate pressure drops using duct calculation methods, mine ventilation network models or computational tools. Because most losses rise roughly with the square of flow, the system curve normally starts near the origin and rises steeply as flow increases.
With both curves prepared, you overlay the system curve on the fan curve. The intersection point is the predicted operating duty: the airflow and pressure the fan will actually deliver when installed in that system. If the intersection lies near the fan’s high-efficiency region and within acceptable power and noise limits, the setup is good. If it falls in a low-efficiency region, close to stall, or beyond motor capacity, you may need to select a different fan size, adjust speed, modify ducts or split the duty across multiple fans.
During commissioning, you can refine your curves by comparing measured field data—airflow, pressure and power—with the predicted operating point. Small discrepancies are normal, but large differences may reveal incorrect assumptions about system resistance, unexpected leakage or incorrect fan rotation. Updating your system curve and re-checking the intersection helps keep the model aligned with reality.
In summary, setting up proper fan curves means using real test data, applying correct density and speed adjustments, building a realistic system resistance curve and matching them to find stable, efficient duty points for your mining or industrial ventilation fans.
