It is important to control the ventilation systems during fire to prevent possible poisoning and the spread of fire effects. The most important parts of ventilation systems; The fire-smoke and smoke control dampers are managed by the fire alarm system.

Those who design fire alarm systems should know the technical terms related to fire-smoke and smoke control dampers, as well as the types and intended use of these dampers in the ventilation systems drawings. In line with this information, damper control devices of the fire alarm system should be designed and specified in the fire alarm system drawings. In this study, the people who are involved in the design, drawing, consultancy and application stages of fire alarm systems; Information that will constitute a resource on fire-smoke and smoke control dampers has been compiled within the framework of relevant legislation, experiences and technological solutions.

FIRE AND SMOKE DAMPER TYPES

Although evaluated in the same product family, fire damper, fire-smoke damper and smoke control damper are products with different features in terms of their functions. “Fire dampers” are used to limit the passage of smoke in the fire-resistant compartment passages of the comfort ventilation systems. If the building has a comprehensive fire detection and alarm system, "fire-smoke dampers" are used to limit the passage of smoke in the fire-resistant compartment passages of the comfort ventilation systems. Smoke control dampers are used to direct the smoke in smoke evacuation systems.

Fire Damper and Fire-Smoke Damper

In the fire compartments, if the ventilation ducts pass through fire-resistant walls, mechanical products that close these passages due to the heat effect of the fire are called "fire dampers". Thanks to the thermic element inside, it closes automatically after a certain temperature (Figure 1). This product is part of the fireproof wall.

Figure 1. Fire Damper

In the first stages of the fire; It is observed that the toxic gases called "cold smoke" progress through the comfort ventilation ducts and cause poisoning. To prevent this situation in buildings; Fire dampers with motors that can be controlled with information and control signals from advanced fire detection and alarm systems are used. These are defined as "fire-smoke dampers" (Figure 2). These dampers are just like fire dampers; It is located in the parts of the canals passing through the fire wall and makes the firewall safe quite early with the warning from the fire alarm system. In this way, the passage of toxic gases or cold smoke is prevented.

Figure 2. Fire-smoke damper

The requirement for the use of fire dampers or fire-smoke dampers directly relates to fire compartments. Each floor is considered as a separate fire compartment in buildings with a height exceeding 21.5 m (30.5 m in residences). Vertical mechanical ventilation shafts are considered as separate fire compartments and fire dampers or fire-smoke dampers are installed in the comfort ventilation ducts going from these shafts to each floor (Figure 3).

Figure 3. Smoke control damper

In buildings where advanced fire alarm systems are installed with an effective sprinkler system, fire-smoke dampers are installed instead of fire dampers that work only with thermal effect (melting wire).

The characteristics and selection of dampers to be used on comfort ventilation systems are as important as determining the scenarios for their control. Currently, there is no single method that is strictly agreed upon. Mechanical designs and selected dampers differ in cases where the smoke evacuation is done separately and the smoke evacuation is done with an aspirator (air return) duct at the same time.

In buildings where fire-smoke dampers are used, it is a generally accepted practice that air handling units continue to operate in case of fire, and the damper of the fire is closed. In the meantime, by keeping the damper of the air return duct of the fired floor open and closing the air return duct dampers of the other neighboring floors, positive pressure is created in the neighboring floors and these areas are not affected by fire smoke and toxic gases (Figure 4). The electricity supply of fire-smoke dampers must be continuously made from a source. If the electrical connection that feeds the dampers is cut, it must be closed with the spring return mechanism.

Figure 4. The behavior of comfort ventilation fire-smoke dampers during a fire

Smoke control damper

Until this part; Information was given about the fresh air ducts provided to the air handling units and the compartments of the building and the fire-smoke dampers used in the air return ducts. This section contains information about "smoke control dampers" to be used in ventilation systems specially designed for smoke evacuation. It is required that the ducts and smoke control dampers to be used in smoke evacuation systems operate or be in use at higher temperatures.

It is required to open the smoke control damper in the compartment where fire occurs. In cases where more than one floor is smoke evacuated with a single duct and fan, the smoke damper of the fire occurring floor is required to be open and the others closed. The reasons for this situation are; It is evaluated as pulling the smoke of the snow that causes a fire with the full power of the fan and providing positive pressure in other floors (Figure 4).

Although it is the same product group, it contains different features than smoke control dampers, fire dampers and fire-smoke dampers.

- Smoke control dampers must come to the open or closed position required by the firefighting scenario and maintain that position (Therefore, it also performs opening and closing with the engine).

- Smoke control dampers should not have heat sensitive trigger elements.

- Smoke control dampers will not change their position in case of a power failure, that means, the spring will not be returnable.

In this context, it is expected that the opening and closing operations of smoke control dampers will be provided with the engine and be resistant to fire for at least 30 minutes.

As can be seen; fire damper, fire-smoke damper and smoke control damper have different functions and different features. When technical terms and product differences are not known correctly by the parties that make the design and drawing of fire detection and alarm systems, deficiencies and inaccuracies arise in design, drawing and application. Table 1 can be used to make it simple and understandable.

Table 1. Dampers and Features

CONTROL OF FIRE-SMOKE AND SMOKE DAMPERS BY FIRE ALARM SYSTEM

In the normal condition in which comfort conditions are provided in the buildings; Fresh air is supplied to the environment through clean air ducts connected to air handling units (referred to as CAD in the drawings of the mechanical design). The ambient air is also evacuated by means of air return or exhaust ducts (referred to as ED in the drawings of the mechanical design). Fire-smoke dampers are installed at the compartment passes of the ventilation ducts that provide these processes. Normally, all of the fire-smoke dampers are open (Figure 5).

Figure 5. Positions of dampers on ventilation system ducts in normal condition

In case of detection of fire smoke, the fire-smoke damper, which provides fresh air to that compartment, is closed by the damper control module connected to the intelligent addressable fire alarm system. The fire-smoke dampers on the air return or exhaust duct of that compartment remains open. Fire-smoke dampers on the air return ducts of adjacent compartments, where air return is provided with the same channel, are closed, preventing toxic gases or cold smoke from reaching these areas. Meanwhile, fire-smoke dampers on the fresh air ducts of adjacent compartments are left open, creating positive pressure in these compartments (Figure 6).

All of the smoke dampers on the smoke exhaust duct (SED) installed in the building are normally closed. In case of fire, the smoke damper on the smoke exhaust duct on the floor opens. Smoke dampers of adjacent compartments on the same smoke exhaust duct continue to remain closed. The smoke exhaust fan (SED) is commanded to be run by the fire alarm system. In this way, smoke evacuation is provided for the compartment where fire occurs.

If the building has a fire escape and pressurization system (PF) installed in the emergency lift shaft, the motorized cover on the pressurization duct is opened and the pressurization fan is operated. These operations are provided by the intelligent addressable control modules of the fire alarm system.

Figure 6. Locations of dampers on ventilation system ducts in case of fire

Today, the monitoring and control of the position of dampers by fire alarm systems are mostly done with more than one relay and switch monitoring modules. This situation; while causing the need for multiple addresses in the fire alarm system, it also creates difficulties in first mounting and after mounting operation. Some companies can perform more than one control and monitoring process from a single address with the new technological products they have developed. These new products control the dampers at 220 V AC, 24 V AC and 24 V DC operating voltages, and perform the opening and closing operations of the dampers with remote control inputs.

At the same time, these products;,

- Tracking of open / short circuit conditions of damper remote control inputs and control outputs,

- Observing the condition of the damper control module cover remaining open,

- Programming the opening and closing time of the damper,

- Monitoring important warnings with LEDs in various colors on the module,

- Showing warnings as messages in the fire alarm system control panel

By offering such facilities, it has made smoke control much more effective and successful (Figure 7).

Figure 7. Example of damper control with smoke damper control module

The connection of smoke control dampers with control modules connected to the fire alarm system is carried out as in the example below (Figure 8).

Figure 8. Connection of smoke control damper with fire alarm system control module

CONCLUSION

Mechanical engineers, who are design experts in the field of ventilation system, have formed an application union on the use of "fire-smoke dampers" instead of "fire dampers" in the ventilation ducts in the fire compartment passages. In smoke exhaust systems, "smoke exhaust dampers" that are fire resistant to certain durations should be used.

People who design and draw fire alarm systems should examine in detail the ventilation systems designed and drawn by mechanical engineers. The products such as fire-smoke damper, smoke control damper, air handling unit, exhaust fan, smoke evacuation fan, pressurization fan must be determined from the mechanical drawings, and the control devices that are suitable for their features must be included in the fire alarm system designs and drawings.