A fan is selected at the point where the required airflow and system pressure intersect. Airflow alone does not confirm whether the fan can overcome the resistance.
The fan curve, system curve, efficiency, motor power and operating margin should be reviewed together. A fan that is too large can waste energy and create control problems.
Gas density, temperature, altitude and medium condition can shift the actual duty. Final selection should use the project operating condition rather than only standard-air catalogue data.
Clean ambient air can use a standard ventilation direction, while hot gas, abrasive dust, corrosive vapor or humid air may require different materials, sealing and drive arrangements.
The fan position also matters. A dust collector fan installed on the clean side sees different conditions from a fan handling dirty gas before filtration.
The minimum information is airflow, pressure, medium, temperature, density or altitude, installation direction, power supply and operating schedule. Duct and equipment resistance should also be included.
Both are required. Airflow determines capacity, while pressure determines whether the fan can overcome the system resistance. A fan must meet both at the same operating point.
Static pressure is the useful pressure available to overcome system resistance. Total pressure includes both static pressure and velocity pressure. The project specification should state which pressure value is provided.
4-72 is generally a medium-pressure ventilation direction. 9-19 is a high-pressure direction for systems with greater resistance. Final choice depends on the actual airflow-pressure point.
Temperature changes gas density, required power and material conditions. The actual inlet temperature should be provided, especially for hot air, flue gas or drying systems.
Yes. Send the fan and motor nameplates, rotation, outlet angle, connection dimensions, airflow, pressure, speed and current operating problem for replacement review.