Primary Duty
Fresh-Air Delivery
Contaminants
Dust, Fumes & Exhaust
Selection Basis
Airflow + Duct Resistance
Project Stage
Construction ≠ Operation
01 · Tunnel Construction Fan Selection
How to Select a Tunnel Construction Ventilation Fan
For a tunnel construction ventilation fan, the primary construction-stage direction is usually ducted fresh-air supply to the heading face. A ducted axial fan such as the SDF direction should be reviewed by the airflow available at the face, the maximum duct route and the complete pressure loss. A tunnel exhaust fan, local ventilation fan or jet fan may require a different arrangement.
Most construction-stage tunnel supply fans on this page use axial-flow principles. For the basic airflow direction, working principle and common axial fan types, see axial fan airflow fundamentals.
Construction Stage
Ducted Axial Fan
Fresh-air delivery through flexible or rigid ducting to an advancing heading face. Review working-face airflow, maximum duct length, diameter, leakage and complete pressure loss.
Special Route
Tunnel Exhaust Fan
Contaminated-air extraction where the duct route, dust condition, fan location and maintenance arrangement are specifically designed for exhaust duty.
Completed Tunnel
Jet Fan System
Longitudinal airflow using SDS tunnel jet fans, reviewed by thrust, tunnel cross-section, installation spacing, noise and operating strategy.
02 · Application Overview
What Tunnel Construction Ventilation Must Achieve
Tunnel construction creates a continuously changing ventilation route. As excavation advances, fresh air must travel farther through ducting while pressure loss, leakage and connection resistance increase. The selected fan must therefore match both the current stage and the expected maximum ventilation distance.
01
Deliver Fresh Air to the Face
Supply the required air volume to the active excavation and working zone through the complete duct route.
02
Dilute Blasting Fumes
Reduce the time required to restore workable conditions after blasting or other high-emission activities.
03
Control Dust & Equipment Exhaust
Support removal of excavation dust, diesel exhaust, welding fumes and heat generated by construction equipment.
04
Adapt as the Tunnel Advances
Maintain useful airflow as the tunnel and duct route become longer and the resistance increases.
03 · Construction Stages
Ventilation Changes as the Tunnel Advances
The operating point changes throughout construction. Fan and duct planning should consider both the initial route and the maximum expected ventilation distance.
01
Portal & Early Excavation
The ventilation distance is short, but dust and equipment emissions may still require controlled fresh-air delivery.
02
Intermediate Tunnel Length
Duct length and leakage increase. Fan pressure and connection quality become more important to maintain airflow at the face.
03
Long-Distance Ventilation
Pressure loss can become the main selection factor. Larger duct diameter, staged fans or a higher-pressure fan direction may be reviewed.
04
Permanent Tunnel Operation
After construction, longitudinal ventilation or jet-fan systems may be used according to the completed tunnel design.
04 · Ventilation Method Selection
Match Tunnel Stage to Ventilation Method
A tunnel ventilation fan is not selected only by fan diameter. The method, duct route, target face airflow and maximum pressure condition decide the correct product direction.
For the commercial product-family comparison between construction-stage SDF fans and operation-stage SDS jet fans, visit Tunnel Ventilation Fans →
05 · Pressure Selection
Why Duct Length, Diameter and Leakage Matter
Tunnel construction fans are often selected for ducted fresh-air delivery. The fan must provide the target airflow after all pressure losses from the complete route are included. A longer duct, smaller diameter, damaged joints, bends and poor connection quality can reduce the actual airflow reaching the heading face.
Required fan pressure = duct friction + bends & transitions + leakage allowance + inlet & outlet losses + project margin
Duct Length
Longer route increases friction loss.
Duct Diameter
Smaller diameter generally raises loss.
Joint Leakage
Connection quality affects delivered airflow.
Bends & Transitions
Local losses add to total resistance.
Elevation / Temperature
Air density changes the operating condition.
The factors above illustrate typical resistance influences only and are not project calculation values. The maximum planned route should be considered during preliminary selection.
06 · Ventilation Methods
Ducted Supply, Exhaust and Longitudinal Ventilation
The appropriate system depends on the tunnel stage, contaminant source, construction method, tunnel length and completed operating design.
◎
Ducted Fresh-Air Supply
A fan pushes fresh air through ducting toward the heading face. This is a common direction for active tunnel construction.
←
Ducted Exhaust Ventilation
Contaminated air is extracted through ducting from the working area. Dust and fan-location conditions must be reviewed.
→→
Longitudinal / Jet-Fan Ventilation
Jet fans create longitudinal air movement in completed tunnels or specific project stages according to the overall tunnel ventilation design.
07 · Selection Data
Parameters Required for Tunnel Fan Selection
The more complete the project data, the more accurately the required airflow, pressure and fan direction can be reviewed.
Tunnel Geometry
Length & Cross-Section
Current and final tunnel length, cross-sectional area, elevation and heading-face position.
Duct System
Diameter & Route
Duct diameter, material, current and maximum length, bends, joints and expected leakage.
Performance
Airflow & Pressure
Required airflow at the working face and any available pressure or resistance calculation.
Construction
Dust & Fumes
Blasting cycle, excavation dust, diesel equipment, welding fumes and other pollutant sources.
Installation
Fan Position & Connection
Fan station location, duct connection, available space, mobility and maintenance requirements.
Electrical
Voltage & Motor Standard
Voltage, frequency, phase, starting method, protection level and any special motor requirement.
08 · Fan Directions
Fan Types That May Be Reviewed for Tunnel Projects
Product series are entry directions only. Final suitability depends on the operating point, duct resistance, tunnel stage and project requirements.
Selection note: Product cards provide entry directions only. Final fan selection must be based on the required operating point, tunnel stage, duct resistance, installation method and applicable project requirements.
09 · Project Type
New Tunnel Projects and Replacement Fan Projects
New System
Plan for the Maximum Ventilation Distance
For a new project, fan and duct planning should consider the maximum tunnel length, construction equipment, contaminant sources and the expected ventilation method.
● Tunnel drawings, length, section and elevation
● Required airflow and maximum duct route
● Excavation, blasting and equipment-emission conditions
● Installation, power and project schedule
● Required airflow and maximum duct route
● Excavation, blasting and equipment-emission conditions
● Installation, power and project schedule
Replacement
Match Existing Connections and Improve Airflow
For replacement, original fan data and the current ventilation problem help determine whether a direct match or corrected airflow and pressure selection is required.
● Existing fan nameplate and model
● Existing inlet, outlet and foundation dimensions
● Current airflow or pressure problem
● Photos, drawings, voltage and operating condition
● Existing inlet, outlet and foundation dimensions
● Current airflow or pressure problem
● Photos, drawings, voltage and operating condition
10 · Project Configuration
Available Configuration Directions
Final configuration is confirmed according to the selected fan, working condition, installation arrangement and project requirements.
Material
Carbon Steel / Special Material
Motor
Voltage / Frequency / Protection
Installation
Base / Support / Duct Connection
Accessories
Silencer / Damper / Flexible Connector
Control
Starter / VFD Where Applicable
Delivery
Export Packing / Split Shipment
Related Tunnel Ventilation Path
Continue from System Design to Product Selection
Tunnel Ventilation Fans
Compare construction-stage SDF and operation-stage SDS directions.
Tunnel Fan Selection Guide
Working-face airflow, duct leakage and operating-point logic.
SDF Tunnel Ventilation Fan
Long-distance ducted fresh-air supply for construction headings.
SDS Tunnel Jet Fan
Longitudinal ventilation for completed road tunnels.
Mine & Tunnel Ventilation Fans
Product-family hub for mine and tunnel ventilation projects.
Underground Mine Ventilation System
Main/local mine airflow networks and heading-face ventilation.
11 · Frequently Asked Questions
FAQ About Tunnel Ventilation Fan Selection
What information is needed to select a tunnel ventilation fan?
Please provide tunnel length, tunnel section, duct diameter, duct length, required airflow, ventilation method, equipment exhaust, dust condition, voltage and operating environment.
Why does tunnel length affect fan selection?
As the tunnel becomes longer, duct resistance and leakage increase. The fan must provide enough pressure to keep airflow at the working face.
Can one fan work for the whole tunnel construction period?
It depends on final tunnel length, duct arrangement and required airflow. Long-distance projects may need staged ventilation or a higher-pressure fan selection.
Which QIYUE FAN series can be used for tunnel ventilation?
Depending on the project, SDF tunnel ventilation fans, SDS tunnel jet fans, JK / DJK local ventilation fans, GD30K2-12 axial fans and other mine and tunnel ventilation fan directions can be reviewed.
Is fan outlet airflow the same as airflow reaching the heading face?
Not necessarily. Duct friction and air leakage can reduce the airflow available at the heading face. The fan operating point should therefore be reviewed together with the complete duct route rather than using free-air airflow alone.
What is the difference between temporary and permanent tunnel ventilation?
Temporary construction ventilation normally uses a ducted fan to deliver fresh air to an advancing heading face or remove contaminated air. Permanent tunnel ventilation may use longitudinal airflow and jet fans after the tunnel is completed.
Is an axial fan or a jet fan better for tunnel construction?
Neither is automatically better. A ducted axial fan is reviewed for fresh-air delivery through a construction duct, while a jet fan is reviewed for longitudinal thrust in a completed or specifically designed tunnel system.
Should selection use the current duct length or the final duct length?
For preliminary planning, the maximum expected ventilation distance should be reviewed. A fan that works on a short early-stage route may not maintain the same delivered airflow after the duct is extended.
QIYUE FAN · Tunnel Ventilation Engineering Support
Send Your Tunnel Ventilation Parameters
Share tunnel length, tunnel section, duct diameter, ventilation distance, required working-face airflow, pressure estimate, construction method, power supply and quantity. QIYUE FAN can review the ventilation route and suitable fan direction for the project.