UL 793

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These requirements cover automatically operated roof vents for smoke and heat that fall into two general categories: mechanically-opened and gravity-opened.Mechanically-opened vents consist primarily of a body frame, one or more damper covers and hatches, and operating mechanisms which generally include a heatresponsive device and spring(s). Gravity-opened vents consist primarily of a body frame and nonmetallic drop-out panel. The vents covered by these requirementsare operated manually or automatically in the event of fire to remove smoke and heat from the building. Automatic operation does not depend on electrical power orother energy sources that may be interrupted during a fire, but rather depends upon operation of a heat responsive device or on the action of a plastic cover shrinkingand falling from place due to fire exposure, or the like. These vents are not intended for use as general purpose building ventilation devices.

A product that contains features, characteristics, components, materials, or systems new or different from those in use when the Standard was developed, and thatinvolves a risk of fire, electric shock, or injury to persons, shall be evaluated using the appropriate additional component and end-product requirements as determinednecessary to mai ntain the level of safety for the user of the product as originally anticipated by the intent of this Standard.

Edition:

1st

Published:

01/01/1995