FIRE CURTAIN OR SMOKE CURTAIN?

A designed Fire Curtain and a designed Smoke Curtain are similar in appearance and operation but that’s where the similarity ends. They are both used for completely different functions and one should never be substituted for the other and used to service the wrong requirement.

A Smoke Curtain is utilised as an integral part of a Smoke Ventilation design and is used to channel to a smoke exhaust point, (whether this be by natural or powered ventilation), or contain smoke to a certain area. Its general purpose is to maintain a higher temperature in the smoke layer so allowing the smoke to rise to the extract point or points. Smoke Curtains are usually not full height (ceiling to floor) but are set at a drop height, generally above head height, so as not to interfere with the means of escape.

However, a Fire Curtain provides a complete fire separation (from underside slab to finished floor level) between designated fire zones, typically to protect an open stairway or to prevent fire moving from one floor to another, through an open atrium. Therefore, as fire-separating elements, Fire Curtains are required to provide two main functions:

1) To maintain any compartmentation of buildings needed to limit the spread of fire and smoke;

2) To allow access to protected escape routes, both vertical and horizontal, without any loss of fire resistance, and to limit smoke entry into these routes, i.e. protected corridors and protected shafts.

TESTING

Given these uses, the curtains are tested to two very different parameters. The latest test standard for Smoke Curtains is BS EN 12101-1:2005+A1:2006 (Smoke and heat control systems. Specification for smoke barriers) which involves the testing of the curtain to temperatures of around 600 degrees C. Whereas, the current standard for Fire Curtains, BS 8524-1-2:2013 (Active fire curtain barrier assemblies. Specification and Code of practice for application, installation and maintenance) which evolved from PAS121 which was withdrawn in 2013, involves fire temperatures which can reach over 1000 degrees C. When used as part of a fire-engineered design solution, fire curtains are a critical element of that design. If the Fire Curtains do not deploy to their operational position, the fire-engineered design solution would be compromised. However, in the event that other fire protection systems or elements do not function, e.g. due to total power failure, the Fire Curtains in the fire-operational position provide fire separation.

“THE REAL WORLD”

The reality of the correct application is very often blurred by the price pressure to deliver the lowest cost option. In these instances, Smoke Curtains are used to replace the requirement for higher cost Fire Curtains. What is not appreciated, is the consequences of this action, which can result in a failure of the curtain and the catastrophic consequences of this occurrence. It has to be understood that these are components of a life safety system and incorrect usage can result, in loss of life and damage to buildings and structures.