Appeal 31868

OMSC 401.4.1 – Air Intake for Generator and NFPA 110, 7.7.2.1

OMSC 401.4.1 states that Air intake openings shall comply with all of the following:

-Intake openings shall be located a minimum of 10 feet from lot lines or buildings on the same lot.

-Mechanical and gravity outdoor air intake openings shall be located not less than 10 feet horizontally from any hazardous or noxious contaminant source, such as gas meters, vents, streets, alleys, parking lots and loading docks provided that the openings are located not less than 25 feet vertically above such locations. Where openings front on a street or public way, the distance shall be measured from the closest edge of the street or public way.

-Intake openings shall be located not less than 3 feet below contaminant sources where such sources are located within 10 feet of the opening.

-Intake openings on structures in flood hazard areas shall be at or above the elevation established by the Flood Plain Administrator for utilities and attendant equipment.

Allow the use of direct ventilation from loading to the generator room through an intake opening.

The proposed project meets all the requirements of OSMC 401.4.1 and NFPA 110 except the emergency generator would use loading for intake air. The on-site generator is located at Level 1 in the Generator Room. The generator requires intake ventilation air for cooling purposes. The generator is within the building and ventilation air is brought into the generator enclosure through a 126”x66” intake opening located on the north wall of the enclosure, bringing in air directly from loading. The proposed design will provide equivalent protection for ventilation air for the generator and includes:

-Loading is fully mechanically ventilated including air required for the generator.

-Loading ventilation air is brought into loading through perforated panels in the roll up door.
The proposed size of the opening is 126”x66” and will be located at 10’-0” from finish floor, removing any concerns from damage from vehicular traffic. Additionally, a sign will be installed below the opening stating the following: “DO NOT BLOCK OPENING, GENERATOR AIR INTAKE”.
This appeal only deals with ventilation and not fire protection. A separate appeal is submitted at the same time as this one for fire protection for the generator room.

The intent of OSMC 401.4.1 and NFPA 110, 7.7.2.1 is to ensure that adequate ventilation is provided to the emergency generator that will not cause the intake air to be blocked or contain contaminants that will harm the generator. Due to the location of the generator within the limits of the building enclosure it is impractical to convey intake air from the building’s exterior wall. Equivalent accommodation for ventilation of intake air is provided by the openings in the loading roll up door with at the building perimeter to provide sufficient air for the generator to continue running in case of a power failure.The generator is drawing air directly from loading through an opening in the north wall of the generator room. Please see granted precedent appeals 20648, 18763, 18726, and 24035 28194.