Having previously covered that sprinkler systems do not operate the way Hollywood would like you to believe the next question that is inevitably asked is “well why not?” Why are sprinklers designed the way they are? Surely they could be more effective?
In an ever increasing world of technology. Why can’t sprinklers be improved? Why can’t they be operated remotely with software? Why not develop a system that manoeuvres a sprinklers to the area when a fire breaks out, instead of installing a system over the entire building? To an extent one can appreciate the ordinary person asking this, as most people who have had a braai believe they know a thing or two about fire. There is one factor that ultimately answers all of the above questions: fire doesn’t behave in a predictable manner, despite how much we humans would like it to.
There are many statistics available on how quickly a fire can spread in a building but a rule of thumb is it can double in size every fifteen to thirty seconds given enough combustible material. Think about that for a second – if a fire breaks out in a full warehouse (like the furniture outlet fire recently in Boksburg) you can safely say there is an abundance of combustible material. In order to operate a sprinkler over the affected area a system would need to detect the heat source and put water on the fire, all within thirty seconds before it would double in size. While not impossible to do once the source has been located, it is the initial response time that is the problem in detecting the fire and then acting on it. By the time a human could detect a fire it would be too late to control it. Using a sprinkler system across the entire building mitigates that factor almost entirely. Take a look at the video below to see the difference between a sprinkler and non-sprinkler protected storage facility.
Well let’s introduce fancy software that tracks temperatures through thermal imaging and then the problem is sorted. Asides from an astronomical cost (which people are already looking to skimp on by installing cheap fire “protection” systems) the problem is once a fire breaks out electrical systems are often disabled due to the high temperatures. This renders the whole system null and void so unless the software can operate without power, installing electrical fail safes aren’t usually an option.
The answer then to the question of design is that a sprinkler has to be so robust as to be “automatic” in operation and will react to a fire when it is usually beyond the ability of human intervention. When the air around the coloured bulb reaches a certain temperature, it shatters, effectively removing a plug form the sprinkler allowing water to spray on the fire. In order for the sprinkler to be effective, it needs to have a constant water supply at a specific pressure to induce the spray pattern and create prewetting of product, otherwise at best you will get one very damp spot in a building while the fire rages around it.
As infrastructure has decayed over time in our country’s water delivery systems, the town’s main supply has dropped in pressure to levels that no longer support the required pressure to sustain continued delivery of water in a system. For this reason more and more areas are advised to have their own pumps (to supply the required pressure) and tanks (to supply enough water for an extended period of time) so that the building is properly protected. Having a well designed sprinkler system that meets all the right standards is useless if there is an insufficient water supply. This is an often overlooked factor in commercial industry.
Think of the Western Cape region where there has been, and continues to be, a drought concern – with a lack of water how would you expect a sprinkler system to be effective if a fire where to break out? At the end of the day, no matter how cleverly designed a system is, if it doesn’t operate autonomously and doesn’t have water it is an expensive waste of time for all parties involved. That is why ASIB inspects to several standards that are designed to address this problem.
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