The LWF Blog
Fire Safety for Healthcare Premises – Ventilation Systems – Part 41September 27, 2018 1:11 pm
In LWF’s blog series for healthcare professionals, our aim is to give information on best practice of fire safety in hospitals and other healthcare premises. In part 40 of this series, we continued looking at the subject of internal fire spread through the structure by discussing ventilation systems. In part 41, the location and operation of fire and smoke dampers and fire dampers, begun in part 40, will be continued.
It should be noted that in order for fire dampers to function correctly and retain integrity against the passage of fire, for the period of time indicated, that they must be installed as per the manufacturer’s instructions. The dampers will have been tested according to these instructions and to not use them as instructed means they may not work as intended. The dampers should be securely fixed to the construction they are protecting. A damper must not be supported only by the brickwork, timber battens, frames etc. in which it is located. Any supporting elements used to fix the damper must be constructed of materials providing the fire resistance required.
Dampers in 30 minute fire-resisting ceilings should be supported either by the ceiling or from the structural soffit. Where they are supported by the ceiling, it is essential that the integrity of the fire-resistance is maintained and so, as an example, it would not be acceptable to form an opening, install a diffuser or grille and fit a damper above if the gap between the ceiling opening and the damper does not also achieve 30 minutes’ fire-resistance.
In the case of some specialist ventilation systems, the use of dampers is not recommended and fire rated ductwork will be required as an alternative. Some examples of situations where this might be the case are in the provision of fume cupboards, isolation rooms and kitchen extract systems.
The fire rated ductwork must meet the same performance requirements as the elements through which it passes and should be installed as per the manufacturer’s tested instructions.
Where ventilation systems utilise air transfer grilles, cold smoke air transfer grilles (activated by AFD) can be used in fire hazard rooms, doors to fire hazard rooms and doors in sub-compartment walls only.
The fire resistance element may be achieved through the use of fire-resistant ductwork materials or by applying a protective material.
While in many circumstances, the ventilation system would be fitted with an automatic shut-off in case of automatic fire detection, this is not always the case in a healthcare venue. Automatic shut down of ventilation can impede air-flow paths and room air dilution rates, leading to an increased risk of healthcare-associated infections. In cases where the ventilation system does not automatically shut down in case of a fire, override facilities should be provided so that shutdown can be achieved via panels located at department entrances or adjacent to the main fire alarm indicator panels.
In part 42 of this series, LWF will move on to discuss Cavity Barriers. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact Peter Gyere in the first instance on 0208 668 8663.
Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 25 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.
While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.