QIYUE FAN · SELECTION KNOWLEDGE
Industrial Fan Airflow and Pressure Explained
Airflow tells us how much air must move. Pressure tells us how much resistance the fan must overcome. Industrial fan selection works only when both values are checked together at the same operating point.
Ducts, elbows, filters, collectors, silencers, dampers and outlets all change the required pressure. That is why the same airflow can require very different fan models in different systems.
Selection Logic
Airflow + Pressure = One Operating Point
01 · Airflow
How much air must move
02 · Pressure
How much system resistance must be overcome
03 · Fan Curve
Where the fan can deliver both values together
04 · Motor Power
Confirmed after the duty point is established
Do not select by maximum airflow alone.
In This Guide
Selection Basics
Four Values That Must Be Read Together
Airflow, pressure, operating point and motor power are not independent values. They are part of the same fan-selection decision.
01 · Airflow
How Much Air Must Move
Usually expressed in m³/h, m³/s or CFM. It must match the ventilation, cooling, combustion or dust-capture demand.
02 · Pressure
Resistance the Fan Must Overcome
Ducts, elbows, filters, collectors, silencers, dampers and outlets create resistance.
03 · Operating Point
Airflow + Pressure Together
A fan should be selected at one working point, such as 18,000 m³/h at 2,400 Pa.
04 · Motor Power
Confirmed After Fan Curve
Motor power is checked after duty point, fan speed, efficiency and suitable margin are established.
Basic Definition
What Does Airflow Mean in Industrial Fan Selection?
Airflow is the volume of air or gas delivered by the fan per unit of time. In industrial projects, airflow may be required for workshop ventilation, dust extraction, boiler combustion air, drying ovens, cooling systems, tunnel ventilation or chemical exhaust.
Airflow should be calculated from the process demand instead of simply choosing the largest fan. Too little airflow may fail to remove dust, heat or gas. Too much airflow may increase noise, power consumption, duct velocity and filter load.
Typical Units
m³/h · m³/s · CFM
Workshop ventilation
Often derived from air-change or process demand.
Dust extraction
Based on capture velocity and hood/process demand.
Boiler / process air
Based on combustion or production requirements.
Pressure Definition
What Does Fan Pressure Mean?
Fan pressure is the energy the fan provides to overcome resistance in the air system. Every duct, elbow, filter, silencer, collector or connected piece of equipment creates pressure loss.
Static Pressure
System Resistance
Used to overcome duct loss, elbows, filters and outlet resistance.
Velocity Pressure
Air-Speed Component
Related to air velocity in the duct or outlet and changes with duct area.
Total Pressure
Static + Velocity Pressure
Confirm whether the project and fan curve use static pressure or total pressure.
Need the exact terminology? Read Static Pressure vs Total Pressure. If no pressure value is available yet, continue with Static Pressure Unknown.
Selection Rule
Airflow and Pressure Must Be Matched at the Same Operating Point
A fan does not deliver maximum airflow and maximum pressure at the same time. After installation, it works where the fan curve and system resistance curve meet.
01
Required Airflow
m³/h or CFM demand
02
System Resistance
duct + filter + outlet
03
Fan Curve
model + speed + pressure
04
Working Point
real airflow and pressure
Example: 18,000 m³/h at 2,400 Pa is one operating point. It is not enough to check 18,000 m³/h alone. Use the Fan Performance Curve guide to confirm the actual working point.
Application Review
Different Systems Need Different Airflow and Pressure Balance
The same airflow can lead to a different fan direction when duct resistance, filtration, temperature or process equipment changes.
| Application | Airflow Focus | Pressure Focus | Fan / Selection Path |
|---|---|---|---|
| Workshop Ventilation | Large air exchange volume | Low to medium resistance | Axial Flow Fans |
| Dust Collection | Capture airflow at hoods | Duct + filter resistance | Dust Collection Fans |
| Baghouse System | Stable capture airflow | Loaded-filter pressure drop | Baghouse Fan Selection |
| Boiler Draft | Combustion air or flue-gas volume | Furnace and flue resistance | Boiler Fans |
| Long Duct System | Process airflow requirement | Higher friction and elbow loss | Centrifugal Fans |
Common Mistakes
Common Airflow and Pressure Mistakes
Mistake 01
Selecting by Maximum Airflow
Maximum airflow is usually measured at very low resistance and does not represent real duct operation.
Mistake 02
Ignoring Filter Resistance
Dust collectors, bag filters and scrubbers can dominate total system resistance.
Mistake 03
Mixing Static and Total Pressure
The project pressure basis and fan curve pressure basis must be confirmed before model comparison.
Technical Next Steps
Continue by Selection Topic
Move from basic airflow and pressure understanding into pressure basis, operating point, motor power and full project review.
Main Selection Route
Industrial Fan Selection Center →
Organize airflow, pressure, medium, temperature, installation and electrical data.
Pressure Basis
Static Pressure vs Total Pressure
Avoid mixing pressure definitions in fan selection.
Missing Data
Static Pressure Unknown
Continue from duct, equipment and resistance information when pressure is missing.
Power
Industrial Fan Power Calculation
Estimate shaft and motor power after the duty point is established.
FAQ
FAQ About Industrial Fan Airflow and Pressure
Can I select a fan by airflow only?
No. Airflow must be matched with pressure at the same operating point. A fan with enough airflow at low pressure may fail in a high-resistance duct system.
Why does airflow drop after installation?
A common reason is underestimated system resistance. Long ducts, elbows, dampers, filters, dust collectors or outlet stacks can reduce the actual airflow.
Is static pressure the same as total pressure?
No. Static pressure is used to overcome system resistance, while total pressure equals static pressure plus velocity pressure.
Should baghouse filter resistance be included?
Yes. For baghouse dust collection systems, filter resistance and loaded-filter pressure drop should be included in the pressure review.
Which fan is better for high pressure?
Centrifugal fans are commonly reviewed for duct systems, dust collectors and higher-resistance applications. Axial fans are usually used for larger airflow and lower pressure ventilation.
What information should I send to QIYUE FAN?
Send airflow, static pressure or total pressure, duct layout, filter resistance, working medium, temperature, dust or corrosion condition, voltage, frequency, outlet angle and quantity.
Fan Selection Support
Need Help Confirming Airflow and Pressure?
Send your required airflow, static pressure or total pressure, duct route, filter resistance, working medium, temperature, motor standard and installation direction. QIYUE FAN can review the suitable industrial fan direction for your system.
Airflow · Static Pressure · Total Pressure · Duct Layout · Filter Resistance · Working Medium · Temperature · Voltage · Frequency · Outlet Angle · Quantity