This site is intended as a guide for both industry participants and end users. The methodology of installing Fire Detection systems in South Africa is well documented under formal guidelines issued by SABS called SANS10139. Many end users are going to the expense of having detection systems installed and are assuming that they are being installed to code. At the same time there are many installers of security and fire systems that are installing in good faith but are ignorant to the fact that there is a well documented installation code of practice. This has to be adhered to both from a legal requirement as they are installing a life safety system and from a commercial requirement as a end user does not have insurance cover if their system is proven not to be installed to code in the event of a claim.
We are not trying to formally publish or reword the entire of SANS10139 here but simply identify major aspects of the standard and present them in a way in which even an end user can determine if their system is installed correctly. In all post within this website there is an area to comment and simply create a user name and feel free to comment on all or individual posts. Please refrain from using brand names and company names as we are trying to provide an accurate formal guide and not yet another product placement website. All posts and replies are reviewed before approval and will not be approved if they contain inaccurate, product placements or non-productive comments.
Whilst smoke detectors can be mounted at various heights they can never exceed 10.5 metres above floor level. In many modern office buildings there are triple volume areas, especially at reception which may exceed this height. In industrial environments many warehouses have high roofs that exceed this measurement. In addition to detectors not working correctly they are also very difficult to maintain, requiring specialist lift equipment to perform the routine maintenance. There are specialist detection system that can perform above these heights. If you observe a standard ceiling mount type detector on a ceiling above 10.5m chances are the system has not be fitted correctly.
Reason: As smoke leaves a fire it rises, doing so it looses some of its heat for each meter it rises. This reduces the speed of the smokes accent resulting in two issues:
- The smoke disperses horizontal as it rises (becomes less concentrated)
- Time taken to reach a detector above this level is too long.
The net result is that the amount of smoke required at fire source to generate a smoke alarm activation is too great and would impair peoples escape at floor level before the fire alarm would raise the warning.
There are many external factors affecting the placement of a smoke detector on the ceiling. Here we are looking at if a detector can be fitted close to a vertical wall. The formal guide is that a detector must never be placed anything less than 500mm from a wall. Therefore if you see your detector very close to a wall chances are that it has been installed incorrectly.
Reason: When smoke rises along a vertical surface at the point it contacts the ceiling the smoke rotates as its momentum due to heat cannot carry it any higher and it accelerates along the ceiling. If the detector is too close to this point the smoke has too much momentum and does not settle in the chamber. A smoke detector requires a certain amount of the smoke to gather in the chamber before activation.