19,000 CFM Smoke Exhaust Fan System for Tunnel Ventilation

Sizing Fans for Emergency Tunnel Airflow

A reliable smoke exhaust fan forms the core of tunnel safety. The customer needed a large ventilation system. Their underground project faced strict physical limits. First, normal daily operations needed 11,000 CFM of airflow.

Then, emergency mode demanded a massive jump. The system had to push 19,000 CFM against 500 Pa of static pressure. We received the brief for 33 total units. Specifically, the hardest zone required nine heavy-duty models.

Normal mode clears basic car exhaust. Then, secondary areas needed twenty smaller units. These secondary fans push 4,000 CFM against 300 Pa. Finally, four more units handle 18,000 CFM at just 100 Pa of resistance.

Every model runs on a strict AC 380V power rail. The space inside the tunnel is tight. Therefore, size limits became a major design factor. The tunnel traps moisture and heat.

So, the materials must survive terrible weather. High noise is also a serious risk. Consequently, engineers cap sound levels tightly. Furthermore, the market demands real performance data.

We test all outputs to AMCA 210-16 methods. Any pressure failure leaves dangerous smoke inside the tunnel. In short, the system must push hard against the air without breaking down.

Evaluating Fan Casing and Material Options

We looked at several ways to build this fleet. First, we considered thin galvanized steel frames. Many basic HVAC designs use this light metal. However, we quickly rejected that idea.

A thin frame shakes violently at 2900 RPM. It cannot handle 500 Pa of total pressure. Instead, we moved to thick carbon steel for the main bodies. The primary 9.2 m3/s unit uses a heavy carbon steel shell.

This material choice completely fixed the vibration issue. Consequently, the fan runs smoothly at high speeds. The downside is obvious. The heavier metal costs more to ship and install.

Even so, reliability matters most in emergency systems. The thick metal blocks out low hums. Therefore, the overall noise profile improves slightly.

Finalizing the Smoke Exhaust Fan Dimensions

Next, we focused on the spinning parts. Heavy blades take too long to reach full speed. Therefore, we used aluminum for the impellers. Aluminum blades are very light.

As a result, the motor easily spins them up to 2900 RPM in seconds. Fast starts save lives during a tunnel fire. We used a strong 7.5 kW AC motor for the primary unit. By contrast, the lower-pressure zones needed much less force.

We paired the 19,520 m3/h models with a smaller 5.5 kW motor. This 5.5 kW setup runs at just 1450 RPM. Consequently, this slower speed cuts wear and tear on the bearings. It also drops the noise to a calm 88 dBA.

Matching the Envelope Limits

Finally, we set the exact physical dimensions. The project uses four distinct fan sizes. The smallest unit fits perfectly inside a 560mm outer circle. Meanwhile, the largest unit needs a full 730mm space.

In short, we matched the exact motor and blade to each tunnel section. This careful work saved the customer money. They avoided buying huge 7.5 kW motors for the low-pressure zones.

Technical Specifications

The data above outlines the four exact units. First, you can see how motor power changes. Higher static pressure strictly demands larger motors. Next, notice the spinning speeds. Slower 1450 RPM fans move more air but create less pressure. Finally, the voltage remains steady across all models.

Reference: AMCA 210 covers the test method behind these figures.

Technical Documentation

LWHTF-5.5AFDS-01 Spec Sheet. This PDF shows the 560mm flange size for the 12,390 m3/h unit.
LW-TNJTS6.32D-4P01 Spec Sheet. Engineers use this file to plan the 640mm mount for the main tunnel fan.
LWHTF-6AFDS-01 Spec Sheet. This drawing details the 5.5 kW power layout for the mid-range model.
LWHTF-6.5AFDS-01 Spec Sheet. Installers check this sheet for the large 730mm outer frame details.

Planning Your High-Pressure Fan Build

Follow these exact steps when you face a similar ventilation problem.

• First, measure the true air resistance inside your duct. Many buyers guess this number. A bad guess easily burns out a motor.
• Next, define your physical space limits. You must know your maximum outer flange size. The 730mm unit will not fit in a 600mm hole.
• Then, decide your noise limits early. Fans running at 2900 RPM are loud. You might need to buy extra sound blockers.
• Finally, match the casing metal to your environment. We make our impellers in-house. Therefore, we can help pair a heavy carbon steel shell with light aluminum blades.

Related: Exhaust Fans.

Tunnel Fan Technical Questions

Browse our axial fans range, the AC axial fans section, or EC axial fans.