BS 9251 - An introduction to the standard

We were delighted to be able to present a webinar to our customers which introduced the new BS 9251: 2014 fire sprinkler systems for domestic and residential occupancies – code of practice in which over a hundred people participated, we thought we would like to share our thoughts with a wide audience.

The new standard has considerable differences from the 2005 publication and is showing its maturity in the changes which make this standard highly usable and provides both flexibility and guidance on its use and implementation.

Of course, this introduction is only a taster you cannot possibly cover the whole of the standard in a few PowerPoint slides but hopefully, you will find something useful to take away and if nothing else will give you food thought. Some of the major changes are easy to see such as the introductions of categories of occupancy which is much clearer and resolves the issue of specifiers asking for a residential system when actually they were asking for a domestic. Some other changes will be harder for some to get used to such as the introduction of design densities as opposed to just using the manufacturer's datasheet.

The BS 9251: 2014 is a code of practice and not a standard it only offers guidance and recommendations and it should not be used or quoted as a specification document as this is not the intention or the purpose of a Bsi code of practice. However, if you do deviate you are expected to be able to justify your course of action and remember if you are the designer or the installing company and the system fails it may be the coroner is asking you the questions!

The code of practice also says that only appropriately qualified and experienced people should be allowed to design install and maintain domestic and residential fire sprinkler systems in accordance with the standard, so it's important to have the right training and use the right tools such as our FHC hydraulic calculation software. It's also important to remember that by complying with the British standard or code of practice does not confirm immunity from your legal obligations you have a duty to comply with legislation be it building regulations, water undertakings bylaws, health and safety or other government legislation.


BS 95251 now asks you to consider not only the occupancy of the building (a category the system)  if we have compensatory measures such as deviating from building control requirements or do we have 'vulnerable people' where additional precautions may need to be implemented special or fire strategy. These considerations will need to be carefully considered as they can have a significant on the design which can be offered And in some circumstances it may be at an EN 12845 system would be more appropriate.

One of the manager changes is the introduction of minimum design density for category 1 systems this is 2.04 mm/min and for category 2 and 3 require a higher design density of 2.80 mm/min and you also require a design density of 4.00 mm/min from a single head.  This is a little simplistic as the standard has a great number of footnotes that vary these requirements so you need to read them and the table carefully to get a full understanding of its requirements.

With the introduction of various design densities and areas of operations the life of the sprinkler designer has become a little more difficult, this is where software our FHC software can prove to be of such benefit in the designer's toolkit.  Our FHC hydraulic calculation software can easily calculate residential and domestic fire sprinkler systems which are designed to BS 9251: 2015 it can help you prove that you have the correct design density in the area of operation, Help you optimise the system so it is cost-effective and produce industrial standard reports which are accepted by authorities having jurisdiction throughout the world.  FHC also has an automatic pipe sizing option which is proven to work extremely well on such projects, perhaps it's no wonder that FHC is used by all the leading domestic and residential fire sprinkler installers in the United Kingdom.

 Canute LLP has played a major role in the development of residential and domestic systems over the last 15 years and is helping to shape both National and European standards through our work at Bsi and CEN.  With this experience, we can give our customers the support and training they require to help them through any design issues which they may encounter with the hydraulic calculations or other design principles relating to BS 9251.

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