The development of axial flow fans for the venting of hot fire smoke

Abstract

From an investigation into the technology of calculating ventilation rates to testing and certification, the paper outlines the development of axial flow fans for the venting of hot fire smoke. It deals with an installation effect that in most cases will never arise, but nevertheless is assuming increasing importance in fan system design, that is, the response of the system to the emergency conditions that arise in the event of a fire.

While at one time the natural reaction was that a fire is best dealt with by depriving it of oxygen, now the maintenance of air flow is considered essential for two basic reasons: (1) To keep escape routes clear of smoke and thereby facilitate the safe evacuation of occupants and (2) to assist the fire brigade by enabling them to find the seat of the fire on arrival at the site and by preventing or limiting the phenomena of either flashovers, which can occur when the smoke temperature reaches 600°C, or backdrafts, which result from a build-up of carbon monoxide in the hot smoke.