itl Smoke Control Curtains "Design Parameters and Application Notes"

itl Smoke Control Curtains have been designed as an economic solution to the particular smoke control problem, as illustrated on the following pages, they may work in other applications but are not endorsed as suitable for any other use without further testing, and appraisal by competent fire safety engineers. In other applications alternative fabric in the same cabinet design may be required.

In these applications the curtain design is intended to limit air induction in smoke plumes, rising to smoke extraction fans, through or past the edges of floors above the floor of fire origin. The curtains are deployed to block openings through which air enters the plume thus reducing the size of smoke extract fan(s) required. In these circumstances the curtains also prevent smoke from entering the floors above the fire improving their tenability and making them available as fire escape routes.

The curtains allow a small leakage at the overlap between drops, this is not normally significant where fan induced pressures draw air from the clean side of the curtains to the smoke side but could cause deterioration in tenability on the "clean" side if the smoke is at higher pressure than the clean side. Air leakage should be calculated on the basis of a 2mm gap full height between drops and where edge drops seal to a building surface parallel to the curtain. Where the edge drops have to seal to a building surface at an angle to the curtain a larger gap should be used, the gap width depending on physical arrangement.

The curtains should be arranged to fall on the low pressure side of handrails or similar located at the floor edge. The overlap should be evenly arranged between drops with a double overlap at edge seals to building work to allow for irregularities in building work. Any air gap below the dropped curtain (and handrail) needs to be allowed for in the calculation of smoke extraction rate.

The construction of the curtains and their enclosures is such as to ensure that they are able to resist high smoke temperatures, however they are thermally "thin": and if used close to escape routes should be considered to offer a heat radiation hazard at the same source temperatures as the smoke they are containing. (Where protection from higher radiant heat temperatures is required alternative cloths should be incorporated into the specific design for that application).

As an active part of a building's fire safety systems all smoke curtains should be included in the building's compliance schedule and tested regularly. Although this design is auto release it uses manual reset therefore this testing, if not carefully planned, could become a significant part of the routine maintenance costs. The design incorporates the following features to minimise this cost.

a) Cabinets can be operated individually, to test their freedom of action, to release the curtains within, or to check the "fit" of a curtain to a wall or column.

b) When being tested the cabinets curtain drops can be restrained from dropping, by means of pins inserted under the rolled curtains, so that the electrical circuitry holding the doors closed can be tested without having to drop and re-roll all the curtain drops.

The pins used should be:
(i) Engaged from the outside only.

(ii) Should be positioned, so that in place, they are visibly obvious to casual inspection from ground floor level, thus ensuring that they are not left in place, when the system is returned to operative mode.

(iii)The pins should be end flagged with safety/contrast colour tags or flags.

c) When the doors are released electrically against retaining pins the cabinet doors will fully open, and the curtains condition and situation can be inspected. All doors of any system can then be magnetically locked closed, and then the curtain retaining pins Must be Removed as the system is returned to "active" state.

d) Where it is elected Not To Have Pre-Painted or Powder Coated Cabinets, care must be taken to ensure that any on site painting of the Cabinets precludes paint contamination of the door hinge and adjacent facing surfaces of the cabinet doors and cabinet body. After any on site painting all cabinets doors should be checked for full and un-hindered function. This of course can be done with the restraining pins in place, thus eliminating the need to re-roll the curtains.