QIYUE FAN · FAN SELECTION KNOWLEDGE
Static Pressure vs Total Pressure in Industrial Fans
Static pressure, velocity pressure and total pressure are related, but they are not interchangeable. Before comparing fan models or performance curves, confirm which pressure basis the project actually uses.
This distinction matters in duct systems, baghouse dust collectors, scrubbers, industrial exhaust lines and other systems where resistance determines the real operating point.
Pressure Relationship
Total Pressure = Static Pressure + Velocity Pressure
Static Pressure
Resistance the fan must overcome
Velocity Pressure
Pressure associated with air speed
Total Pressure
Combined pressure used for performance review
Always match airflow and pressure at the same operating point.
In This Guide
Quick Answer 01
Static Pressure
Pressure used to overcome system resistance such as ducts, elbows, filters, dampers and outlets.
Quick Answer 02
Velocity Pressure
Pressure associated with air velocity in a duct or outlet. It changes with air speed and duct area.
Quick Answer 03
Total Pressure
The sum of static pressure and velocity pressure. Some fan curves are rated by total pressure.
Quick Answer 04
Selection Rule
Always match airflow and pressure at the same operating point, and confirm whether the curve uses static or total pressure.
Pressure Basics
Pressure Must Match the Real System
In fan selection, pressure is not a single simple number. Buyers may see static pressure, total pressure, duct resistance or pressure drop in different documents. If these values are mixed incorrectly, the selected fan may not deliver the required airflow after installation.
01
Required Airflow
m³/h or CFM
02
System Resistance
duct + filter + outlet
03
Fan Curve
model + speed
04
Working Point
real airflow and pressure
Selection rule: airflow without pressure, or pressure without airflow, cannot confirm the fan model. If system pressure is not available yet, use the Static Pressure Unknown guide to continue the engineering review.
Static Pressure
What Is Static Pressure?
Static pressure is the pressure available to overcome resistance in the air system. For industrial fans, this usually means duct friction, elbows, filters, dampers, silencers, dust collectors, scrubbers, heat exchangers and final discharge resistance.
When a buyer says a fan needs 2,500 Pa static pressure, the value should ideally represent the resistance of the complete system at the required airflow. If part of the system is missing from the calculation, the fan may lose airflow after installation.
Static Pressure Includes
Duct and elbow loss
Long ducts and multiple bends increase resistance.
Filter resistance
Bag filters, cartridge filters and scrubbers can dominate total resistance.
Outlet loss
Stacks, nozzles and discharge hoods should not be ignored.
Total Pressure
What Is Total Pressure?
Total pressure is the sum of static pressure and velocity pressure. It describes the total mechanical energy in the airflow at a measurement point.
Some fan curves are based on total pressure, while some project documents require static pressure. Before comparing a fan model, buyers and suppliers should confirm which pressure value is being used.
Pressure Relationship
Total Pressure = Static Pressure + Velocity Pressure
Static Pressure
Used to overcome system resistance.
Velocity Pressure
Associated with the speed of air in the duct.
Total Pressure
Combined pressure value for fan performance review.
Selection Risk
Common Mistake: Comparing Static Pressure with Total Pressure
A common selection mistake is comparing a static pressure requirement directly with a total pressure fan curve, or comparing a total pressure requirement with a static pressure curve. The result may be an oversized or undersized fan.
Mistake 01
Only checking fan model
Model name cannot confirm the required operating point.
Mistake 02
Mixing pressure terms
Static pressure and total pressure should not be treated as the same value.
Better Method
Confirm curve basis
Check whether the fan curve and project requirement use static pressure or total pressure.
Dust Collection Example
Example: Dust Collection Fan Pressure Review
A dust collection system may require 18,000 m³/h airflow. The duct route, elbows, baghouse filter and stack create total resistance. If the fan is selected only by airflow, the system may not capture dust effectively.
| Item | Example Value | Selection Note |
|---|---|---|
| Required airflow | 18,000 m³/h | Confirm simultaneous working points. |
| Duct and elbow loss | 800 Pa | Depends on route length and fittings. |
| Baghouse resistance | 1,200 Pa | Check loaded-filter condition. |
| Outlet and margin | 400 Pa | Include stack or discharge loss. |
| Fan pressure direction | About 2,400 Pa | Check fan curve at 18,000 m³/h. |
Selection note: for baghouse systems, do not use only clean-filter resistance. Loaded-filter pressure drop is often more important for real operation.
Application
Industrial Dust Collection System
Review the complete application path from capture point to collector and discharge.
Selection Guide
Baghouse Fan Selection
Check filter resistance, loaded-filter pressure drop and fan position.
Buyer Checklist
Which Pressure Should Buyers Provide?
For quotation and preliminary fan selection, buyers should provide the pressure value stated in the project design or equipment requirement. If the pressure basis is unclear, provide all available system data so QIYUE FAN can help review the fan direction.
Required airflow
m³/h or CFM
Static pressure or total pressure value
Confirm the unit and curve basis.
Filter or collector resistance
Include loaded-filter pressure drop if available.
Duct layout
Length, diameter, elbows and branches.
Working medium
Dust, gas, temperature or corrosion condition.
Motor and installation
Voltage, frequency, speed and outlet direction.
Technical Next Steps
Continue the Pressure Review
Use the pressure basis first, then continue into the relevant selection, performance or product path.
If Pressure Is Unknown
How to Select an Industrial Fan When Static Pressure Is Unknown →
Start from duct, equipment, system resistance and available project information.
Performance
Fan Performance Curve
Understand how fan curve and system curve create the operating point.
Product Family
Centrifugal Fans
For duct systems, dust collectors and medium-to-high pressure applications.
Selection Hub
Industrial Fan Selection Center
Organize airflow, pressure, medium, temperature, layout and electrical data.
Fan Pressure FAQ
FAQ About Static Pressure and Total Pressure
Is static pressure the same as total pressure?
No. Static pressure is used to overcome system resistance such as ducts, elbows, filters and outlet loss. Total pressure equals static pressure plus velocity pressure.
Which pressure should I provide for fan selection?
Provide the pressure value shown in your project specification and clarify whether it is static pressure or total pressure. If you are not sure, send the full duct, filter and outlet information for review.
Why does fan airflow drop after installation?
A common reason is underestimated system resistance. Long ducts, elbows, dampers, silencers, baghouse filters or outlet stacks can increase resistance and reduce actual airflow.
Can I select a fan only by pressure?
No. The fan must meet airflow and pressure at the same operating point. Pressure without airflow, or airflow without pressure, cannot confirm the correct fan model.
Should baghouse filter resistance be included in static pressure?
Yes. For baghouse dust collector systems, filter resistance and loaded-filter pressure drop should be included. Clean-filter resistance alone may not represent real operating resistance.
What should I send to QIYUE FAN?
Send airflow, static pressure or total pressure, duct layout, filter resistance, working medium, temperature, voltage, frequency, outlet angle and installation requirement.
Fan Selection Support
Need Help Checking Fan Static Pressure?
Send your required airflow, static pressure or total pressure, duct layout, filter resistance, working medium, temperature, fan speed and motor standard. QIYUE FAN can help review whether the fan pressure direction matches your real system resistance.
Airflow · Static / Total Pressure · Duct Length · Filter Resistance · Working Medium · Temperature · Voltage · Frequency · Outlet Angle · Quantity