Bridge Dehumidification System

Why do we use a ventilation system or more precisely dehumidification system? We have 2 main causes. These:

1. Extending the operational lifetime of the bridge
2. Reducing the maintenance costs of the bridge

In addition to these two main items, extra advantages such as reducing initial investment costs are also provided. Reducing the lining thickness that will need to be built into the bridge deck and thus cost reduction is also ensured.

Well, I guess everybody thinking about how to provide this. Before going into the bridge application, let me talk about the working principle of the dehumidification system used and the desired working conditions of the system.

At the heart of the dehumidification system is the Silica Gel Rotor (also known as a desiccant dehumidifier or chemical rotor dehumidifier) type dehumidifier. Inside the dehumidifier, there is a rotor similar type to the heat recovery rotor, but whose main purpose is to provide moisture transfer. The device keeps the water particles in the air content on the rotor surface from a certain cross-section (Process cross-section), thanks to the air currents flowing in two different directions, and ensures that the dried air comes out of the rotor surface. When the rotor, which makes the continuous rotation, comes to the regeneration air section, it transfers the water particles to the takes fresh air from outside the room and dries itself of the rotor.

You can watch the videos of the DST Seibu Giken to better explain the working principle.

Now we have explained the working principle of the system used as much as possible. Let's now come to the target condition in which the system is designed. The bridge deck and the main carrier cable work to be kept at and below 40% RH in 12 months of the year, regardless of the temperature.

You can easily see the reason why 40% RH is requested from the result of the research conducted by The Swedish Defence Materiel Administration. When the relative humidity decrease below 60%, the formation of corrosion on the surfaces drops dramatically. In other words, water particles in the air are prevented from condensing on the surface.

Yes, now we have information about how and why the system works. Now let's talk about the dehumidification systems on the bridge. A dehumidification system is used at 4 main points throughout the bridge. These:

1. Main Cables
2. Steel Deck
3. Tower
4. Anchorage Rooms

You can follow the details about the working principle of the systems in the coming days.