Trane BAS-APG001-EN manual Smoke dampers, Pre-installationconsiderations

Chapter 2 Pre-installation considerations

The smoke control system controls fans and positions dedicated and nondedicated dampers, both in the smoke control zones and at the air- handling systems. It may also position dampers or air modulation devices such as variable-air-volume (VAV) boxes serving the smoke control zones. Equipment associated with the smoke control system includes: dampers, fans, verification of operation equipment, and the Tracer™ MP581 programmable controller.

For VAV-based systems, there must be some form of duct pressure relief on each floor or in each smoke control zone. In smoke control mode, all return and supply dampers will be set to 100% open. If the VAV dampers are closed when this occurs, the duct pressure may be enough to damage duct work. To avoid this possibility, duct pressure relief dampers, either DDC or mechanically controlled, should be installed in the ductwork for each smoke control zone.

It should be noted that careful sizing of smoke control supply air damper and relief damper is necessary to use smoke purge and protect dampers.

In contrast to a VAV system, it is not necessary to provide separate duct pressure relief in constant volume as this is a form of dedicated smoke purge with supply and return/exhaust dampers already open. Supply dampers should be sized such that any one damper can spill an adequate amount of air.

Outdoor air, return air, relief, and exhaust dampers

A nondedicated comfort control system controls outdoor air, return air, relief, and exhaust dampers. In normal operation, the return damper operates in opposition to the outdoor air damper. However, during smoke control system activation, all three dampers may be closed simultaneously to isolate the air-handling system for smoke control operations.

An elevator shaft damper, located at the top of a hoistway, relieves pressure generated during elevator operation. Since elevator shaft dampers are usually open, the natural stack effect of the building will tend to distribute smoke through the building via the elevator shafts. Some codes require a key-operated switch at the main floor lobby to close the elevator shaft damper. With local approval, this switch can be located at the FSCS.

Smoke dampers

A smoke damper is located in any duct that penetrates a smoke zone perimeter. Smoke dampers that are listed by Underwriters Laboratories (UL) are subject to more stringent leakage tests than are standard control dampers. The listing usually includes the control actuator as part of the smoke damper assembly, but does not include the end switches.

IMPORTANT

Smoke dampers must have a Underwriters Laboratories (UL) listing for smoke control applications (UL 555S).

24 BAS-APG001-EN