Airflow tells you how much air the fan moves. Pressure tells you how much resistance the fan can overcome. Industrial fan selection only works when both values are matched at the same operating point.
A fan with high airflow may still fail in a high-resistance system. A high-pressure fan may also move too little air for a large ventilation requirement.
The fan does not automatically deliver the catalogue maximum airflow. It operates where its pressure capability equals the resistance of the connected system.
Shows how much pressure the fan can produce at different airflow values for a stated speed and gas condition.
Shows how the connected duct and equipment resistance increases as airflow rises.
The intersection determines the actual airflow and pressure after the fan is connected to the system.
Changing a damper, filter, duct or fan speed moves the operating point and changes real performance.
Pressure terminology must be clear before comparing fan data, engineering calculations and customer specifications.
Every component in the air path consumes part of the available pressure. The correct pressure value comes from adding the complete route.
Before comparing specifications, confirm that all values use the same units and the same reference condition.
Fan laws are useful for estimating changes on the same fan under similar gas conditions. They are not a replacement for final curve verification.
Airflow changes approximately in direct proportion to fan speed.
Pressure changes approximately with the square of fan speed.
Power changes approximately with the cube of fan speed, so motor load rises quickly.
This simplified example shows why one value cannot replace the other.
Check how many extraction points operate together and whether leakage or future allowance is included.
Include hoods, branches, main duct, dust collector, damper and final outlet.
Confirm whether the fan is on the dirty side or clean side and whether abrasion protection is required.
Select the fan where 20,000 m³/h and 2,800 Pa meet in a stable curve region.
Most selection problems come from missing system information rather than from the fan model itself.
Maximum airflow is usually measured at very low pressure and may not represent the project operating point.
Filters, scrubbers, heat exchangers and dust collectors can consume more pressure than the duct itself.
A static-pressure requirement cannot be compared directly with a total-pressure curve without checking the measurement basis.
Hot gas and high-altitude conditions change density, pressure capability and absorbed power.
Oversized fans can waste energy, increase noise and make control unstable.
Power rises approximately with the cube of speed and may exceed motor or mechanical limits.
Use the related technical and application pages to move from basic understanding to a specific fan direction.
Airflow is the volume of air or gas moved per unit time. It is commonly used to describe fan capacity, but the stated airflow is meaningful only together with the required pressure and operating condition.
Because the fan may not produce enough pressure to overcome ducts, filters, heat exchangers, scrubbers or other resistance. The actual operating point is determined by both the fan curve and the system curve.
Static pressure is the pressure available to overcome system resistance. Total pressure equals static pressure plus velocity pressure. Project documents should clearly state which pressure value is required.
Higher speed can increase airflow and pressure, but power rises rapidly and the motor, impeller, bearings, vibration and noise must be checked before changing speed.
Temperature changes gas density. A fan may move a similar volume, while pressure and absorbed power change with density. Hot-gas selection should use the actual inlet condition.
Send required airflow, required pressure, medium, temperature, dust or corrosion condition, duct and equipment resistance, installation direction, motor power standard and operating schedule.
Qiyue Fan can review your airflow, static or total pressure, gas condition, temperature, system resistance, installation and power standard before recommending a suitable fan direction.