The small water droplets have relatively small mass and thus remain airborne longer to enable them to continue to absorb heat and, at the same time, are able to flow with the thermal air currents, so water is drawn into the seat of the fire even when it may be shielded from the direct discharge from the watermist nozzles.Īs a result, watermist extracts heat, cools combustion gases and blocks the radiant heat transfer, thereby preventing the spread of fire. This increased water droplet surface area also enables the droplets to capture soot particles in the killer smoke, thereby improving visibility. This greatly increased surface area of the water droplets means a similarly increased ability to absorb heat and thereby cool the surroundings, significantly improving survivability of those threatened by fire.
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In contrast a watermist nozzle delivering droplets of around 100 microns produces a surface area of 200m2 from one litre of water. These characteristics can only be exploited if and when the water is delivered in the form of small droplets with sufficient momentum to penetrate the fire plume.įor example, an automatic sprinkler produces droplets around 1mm diameter with a litre of water having surface area of 2m2. Thirdly, in converting to steam it expands 1620 times its volume. Secondly, once it reaches 100°c it converts to steam, and in doing so absorbs a very large amount of heat. Firstly it absorbs a relatively large amount of heat to raise its temperature. Although the concept was discovered over 100 years ago it has only been in the past 20 years that the knowledge and technology has existed to exploit its fire-fighting benefits.Īlthough a common commodity, water has unique properties with regard to fire fighting. Watermist, as the name implies, utilises water broken up into very small droplets. One such system is a watermist fire protection system.
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#Hospital fire sprinkler system design install#
One of the most effective ways to safeguard these vulnerable members of society is to install an automatic fixed fire protection system which would react to incipient fire and suppress it at source.
#Hospital fire sprinkler system design full#
For full evacuation, staff would have to rely on the arrival of the Fire & Rescue Service, however, the time for a fire crew to arrive is variable – as current and projected cutbacks in Fire & Rescue Service resources bite. Staffing levels are rarely high enough to carry out such arduous labour. The problem is compounded due to the limited capacity of staff to be able to evacuate all those unable to do so themselves. The patients/residents often have limited ability to respond to any alarm, as they are either incapacitated physically, through injury or infirmity, or incapacitated mentally, through age or dementia.
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Fire detection is a standard requirement but, in healthcare facilities in particular, is of limited value. Fires will usually involve furnishings giving off quantities of heat and smoke, which is the primary cause of deaths from fire. Fire in healthcare facilities poses various challenging situations.