Appeal 32364

NFPA 110, 2014 OSSC Sections 7.2.1.1 and 7.7.2.3, and OMSC 607.5.2

Ducts and air transfer openings that penetrate fire barriers shall be protected with listed fire dampers installed in
accordance with their listing.

The emergency generator room must be separated from the rest of the building by construction with a 2-hour fire resistance rating. In addition, these rooms require ventilation air to be supplied directly from the building exterior or through ductwork with a rated 2-hour construction without the use of any fire/smoke dampers which could prevent air from entering or exhausting the room.

The intent of the appeal is to allow deluge sprinkler heads at opening in lieu of the fire/smoke damper.

This appeal would allow an emergency generator intake vent in a 2 hour rated wall without a fire damper and added deluge sprinkler heads.

The on-site generator is now located in the basement Level P1. The generator room requires a two-hour rated enclosure (fire barrier) constructed in accordance to OSSC Section 707. The generator requires ventilation air for cooling purposes. If the openings in the two-hour wall were protected with fire smoke dampers, this would disable the generator because it would prevent combustion and cooling air from reaching the generator in cases of emergency.

The engine radiator cooling airflow is 10,800 cubic feet per minute. The relief air is ducted directly from the exterior via a louver in the generator room. The generator flue exhaust of 1,200 cfm is being taken to the exterior wall on level 1 in a 2-hour shaft. The total generator intake of 12,000 cubic feet per minute is drawing air from the garage via a 24 square foot opening.

The proposed design that will be implemented to provide an equivalent level of protection to the generator enclosure will include:
• Installation of two fire sprinkler heads above the intake louver located on the east wall of the generator enclosure; one located on the interior side of the enclosure, and one located on the exterior side of the enclosure.
Please see attached plans showing the relief louver and the ventilation being provided by the garage door.

Due to Planning Department’s requirement for the layout of the building, the generator is located within the limits of the building enclosure. This location makes it not possible to provide both intake and exhaust louvers on the non-rated exterior wall. The intake louver has been located in the east wall of the two-hour rated enclosure. The current layout positions the generator enclosure within the type IA portion of the building, and the enclosure can only be accessed by property management.
The alternate strategy of providing dedicated sprinkler heads at the intake opening provides an equivalent level of protection to fire dampers, and enables the generator to function in the event of a fire. It is a method that has been previously approved on similar projects in the City of Portland.

Reference appeal with similar condition: Appeal ID#13885, 13519, 6/1/16; Appeal ID#12880, 12/30/15; Appeal ID#12693, 11/12/15; Appeal ID#16416, 11/31/18