1 February 1999
the outdoors. Where possible, the heating equipment capacity or energy consumption will not
be increased by these areas.
4-6. VESTIBULES. Vestibules may be heated to 10 degrees C (50 degrees F) to melt tracked-
in snow in locations where conditions warrant. Otherwise, vestibules will not be heated or air
4-7. EQUIPMENT ROOMS.
a. Mechanical Ventilation. Equipment rooms will usually be ventilated using outside air
intake louvers and a thermostatically controlled exhaust fan. Use a supply fan in lieu of an
exhaust fan in rooms where atmospheric burners are located. The ventilation fan will have a
two-speed motor, that is sized, at the high speed, to have adequate capacity to limit the room
dry bulb temperature to a maximum of 6 degrees C (10 degrees F) above the outdoor dry bulb
temperature when both equipment and ambient loads are at their maximum peaks. The high
speed will be activated 6 degrees C (10 degrees F) below the maximum temperature at which
the most sensitive item of equipment in the room can operate. The low speed will operate at 11
degrees C (20 degrees F) below that of the high speed.
b. Air Conditioning. Air conditioning may be provided where life cycle cost effective to
prevent severe corrosion in salt-laden areas where, during the six warmest consecutive months,
the wet bulb temperature is 22.77 degrees C (73 degrees F) or higher for over 4,000 hours.
4-8. BATTERY ROOMS. Provide battery rooms with an exhaust fan interlocked with the battery
charger so that the charger will not operate without ventilation. Size the exhaust fan to prevent
hydrogen concentration in the room from exceeding 2 percent by volume. The power ventilation
system for the battery room must be separate from ventilation for other spaces. Air recirculation
in the battery room is prohibited. The fan motors must be outside the duct and battery room.
Each blower will have a nonsparking fan. Consider using a multiple speed fan or multiple fans
when the room is designed for two or more battery chargers. Size the exhaust fan as follows:
Q = 0.025 x I x N
Q = Required ventilation rate in l/sec.
I = 0.21 x (capacity of the largest battery to be charged in ampere-hours) or 0.25 x (the
maximum obtainable amperes from the charger), whichever is greater.
N = (number of batteries to be recharged at one time) x (number of cells per battery). A
single cell is normally 2 volts DC. Therefore, a 6-volt battery normally has 3 cells and a 12-volt
battery normally has 6 cells. Areas used for battery storage in maintenance facilities will be
ventilated at a minimum rate of 7.6 l/sec/m2 (1.5 ft3/min/ft2), with care taken to ensure proper air
distribution to and within the battery storage area.
4-9. KITCHENS AND DISHWASHING ROOMS.
a. Ventilation will be the chief means of preventing heat, odors, and smoke from entering
dining areas and other adjacent spaces. Provide evaporative cooling where effective. Spot air