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Technical questions & answers The BAFSA Technical team receives questions and enquiries daily, some of them more challenging to respond to than others but the team will always provide an appropriate and informed response… Here are just a few.
Will a sprinkler head operate in a ‘dead’ air space where there is no air circulation and not easy to access. The head has a 74°C fusible link with a 57°C cover plate.
answer Sprinkler heads in ‘dead’, hard to access spaces could be problematic because they are not easy to inspect or could be inadvertently overlooked. BS EN 12845 Sprinkler Rules makes a reference to unventilated concealed spaces in paragraph 14.4 but does not mention the accessibility of the space. It states the following: ‘In unventilated concealed spaces it may be necessary to install sprinklers with a higher operating temperature, up to 93°C or 100°C. Sprinkler heads in such spaces will operate if the temperature exceeds their normal operating temperature’. 36 | BAFSA .ORG.UK
We have been told that we cannot use elbows on our proposed new sprinkler system but must use ‘standard bends’. Can you please advise where this is required in the sprinkler rules?
answer Bends usually have a curve to change direction as against and elbow which is nearly a sharp 90° change of direction. The sprinkler rules BS EN 12845 only differentiate between bend and elbow in Table 23 for equivalent lengths used for hydraulic calculations. Maybe someone is confusing the requirements of BS9990 for Wet and Dry risers where it states: “All changes in the direction of the run of the piping should be made with standard bends, springs or long turn fittings. Elbows should not be used.”
NFPA Sprinkler rules have been suggested for a new installation in our building. Are these common for use in the UK?
answer Besides BS EN 12845 Sprinkler Rules the other most commonly used commercial sprinkler design rules used in the UK are NFPA (13 and 20) + F. M. Global Data Sheets. Many American companies who have sites in the UK may have American insurers and they tend to lean towards using NFPA Rules. Probably because they are more familiar with NFPA rules and less familiar with the UK/ European rules. These American standards, though not the most commonly used, are nevertheless familiar to, and used by, sprinkler designers. NFPA are a proven and reliable set of standards for sprinkler systems.
