Tunnel Ventilation by Project Stage
Tunnel ventilation fan selection should start from the project stage. During construction, tunnel ventilation usually relies on duct-based forced air supply to deliver fresh air to the tunnel face. After completion, road tunnel ventilation normally uses jet fans for longitudinal airflow, vehicle exhaust control and smoke exhaust support.
QIYUE FAN provides two main tunnel ventilation fan directions: SDF tunnel ventilation fans for construction-stage duct air supply, and SDS tunnel jet fans for completed road tunnel ventilation.
This page helps buyers distinguish tunnel construction ventilation from road tunnel operation ventilation before entering detailed product selection.

Construction Duct Ventilation vs Road Tunnel Jet Ventilation
SDF and SDS tunnel fans serve different project stages. The key difference is not only the fan model, but also the ventilation method, installation position and selection parameters.
| Item | Construction Stage | Operation Stage |
|---|---|---|
| Typical Fan Direction | SDF Tunnel Ventilation Fan | SDS Tunnel Jet Fan |
| Ventilation Method | Forced air supply through flexible ventilation ducts | Longitudinal airflow generated by tunnel jet fans |
| Main Purpose | Fresh air delivery, tunnel face ventilation, dust and exhaust dilution | Traffic ventilation, vehicle exhaust control and smoke exhaust support |
| Selection Focus | Tunnel length, duct diameter, duct length, airflow and pressure loss | Tunnel length, thrust, installation spacing, noise and smoke control requirement |
Two Main Fan Directions for Tunnel Ventilation
Choose SDF or SDS according to whether the tunnel is under construction or already completed for road traffic operation.
How to Select Tunnel Ventilation Fans
Tunnel ventilation fan selection should first confirm the project stage, then review airflow method, tunnel length, tunnel section, duct or jet ventilation arrangement and operating conditions.
Project Stage
Confirm whether the project is under construction or already completed for road tunnel operation.
Airflow Method
Construction projects usually need duct air supply, while completed road tunnels use jet ventilation.
Tunnel Length
Tunnel length affects duct pressure loss during construction and jet fan spacing during operation.
Airflow or Thrust
SDF selection focuses on airflow and pressure; SDS selection focuses on jet thrust and tunnel airflow control.
Dust and Smoke
Construction dust, blasting smoke, vehicle exhaust and emergency smoke exhaust should be reviewed separately.
Installation Method
SDF connects with flexible ducts; SDS is usually installed on the tunnel ceiling or upper side area.
Typical Applications for Tunnel Ventilation Fans
Road Tunnel Construction
Duct-based air supply for road tunnel excavation, tunnel face ventilation and construction dust dilution.
Railway Tunnel Construction
Long-distance duct ventilation for railway tunnel construction and underground working areas.
Mine Tunnel Excavation
Airflow support for mine tunnel excavation, underground roadway construction and local working areas.
Completed Road Tunnel
Jet fan ventilation for completed highway tunnels, mountain tunnels and urban road tunnels.
Smoke Exhaust Support
Longitudinal airflow and emergency smoke exhaust support for road tunnel operation scenarios.
Tunnel Renovation
Ventilation fan review for existing tunnel improvement, airflow upgrade and smoke control projects.
FAQ About Tunnel Ventilation Fans
What is the difference between SDF and SDS tunnel fans?
SDF tunnel fans are used during construction with flexible ducts for forced air supply. SDS tunnel jet fans are used in completed road tunnels for longitudinal ventilation and smoke exhaust support.
When should a tunnel duct ventilation fan be selected?
A tunnel duct ventilation fan should be selected when the tunnel is under construction and fresh air must be delivered through ducts to the tunnel face or underground working area.
When should a tunnel jet fan be selected?
A tunnel jet fan should be selected for completed road tunnels requiring longitudinal airflow, vehicle exhaust control and smoke exhaust support during operation.
What information is needed for tunnel fan selection?
Recommended information includes project stage, tunnel length, tunnel section, duct diameter, duct length, required airflow, pressure or thrust, power supply, installation method and smoke or dust conditions.
Need a Tunnel Ventilation Fan Direction?
Share your tunnel project stage, tunnel length, tunnel section, duct conditions, airflow, pressure or thrust requirement. QIYUE FAN can help review whether SDF tunnel ventilation fan or SDS tunnel jet fan is more suitable.
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