Lawrence Webster Forrest (LWF), Fire Engineering and Fire Risk Management Consultants
Lawrence Webster Forrest (LWF), Fire Engineering and Fire Risk Management Consultants


Client login
Forgotten password
Follow us on Twitter Follow us on Facebook Subscribe to our blog

Lawrence Webster Forrest
Legion House
Lower Road

Tel: +44 (0)20 8668 8663 Fax: +44 (0)20 8668 8583

Fire Engineering Design and Risk Assessment - Sprinkler Installation Design - Part 36

Posted by LWF: 08/03/2018 11:20

In LWF’s fire engineering blog series for Architects and others in the building design business, we have been looking at what must be taken into consideration when designing a sprinkler installation. In part 35, water supply to the sprinkler system was discussed and in part 36, we continue on that subject, starting with ‘high-rise’ systems.

In the UK, a building containing a sprinkler system where the distance between the highest and lowest sprinklers exceed 45m is classed as ‘high rise’ and certain conditions must be fulfilled. The system which exceeds 45m must be subdivided and each section must have a highest to lowest differential which does not exceed 45m. 

In order to facilitate a constant water supply, each of the sub-divided sections must have its own separate set of pumps or be fed from a separate stage of a multi-stage pump. Multiple pumps may feed from the same water source, which must be sufficient to supply the sprinklers at highest demand.

The use of hydraulic calculations to ascertain the requirements of the sprinkler system was mentioned in previous blogs of this series and in circumstances where this method has been utilised, those calculations will indicate the necessary flow/pressure characteristics of the pumps and size of the storage tanks.

The figures for the most favourable and unfavourable locations, hydraulically speaking, can be plotted on a graph where the linear scale indicates pressure and the square-law scale for water flow. The results will provide a system demand curve which will appear as a practically straight line on the graph. The next stage is to ascertain the figures necessary to plot the design site performance curve for the pump in two different states – when the water tank is full and when the water tank is at its lowest viable level. 

The aim of the graph illustration is to ensure that the installation demand points are all covered by the pump curve when it is at its lowest operational level to ensure that the design flow rate is available as required when the sprinklers are in use.

In addition, consideration must be given to the circumstances of a full design size fire in the area of the most hydraulically favourable sprinkler location. This situation would result in an increased flow rate and must be provided for in terms of pump driver power and tank capacity. The demand curve in this instance should be extended on the graph and the point where it intercepts the pump curve at its highest point is known as Qmax and is used to work out the necessary tank size and pump duty.

In part 37 of this series, we will continue from this point, looking at how Qmax is used to determine tank capacity. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.

Lawrence Webster Forrest has been working with their clients for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact Peter Gyere on 020 8668 8663.

While care has been taken to ensure that information contained in LWF's publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.

Leave a reply





[ Change the image ]


Subscribe to our fire safety blogs

Email Format
* indicates required


  • Fire Engineering Design and Risk Assessment - Compartmentation & Life Safety - Part 5

    In LWF’s Fire Engineering blog series for Architects and others working in the building design business, we have been discussing compartmentation. In part 4 of this series, the ways in which compartmentation supports life safety functions in a fire situation were summarised. In part 5, we look at the ways the issue of compartmentation and life safety is covered in the national building regulations, before looking at the spread of fire. 


  • Fire Safety for Healthcare Premises - Compartmentation & Fire Hazard Rooms and Areas - Part 39

    In LWF’s blog series for healthcare professionals, the aim is to give information on best practice of fire safety in hospitals and other healthcare premises. In part 38 of this series, the importance of fire stopping the joints between fire separating elements such as walls and any openings was discussed. In part 39, we will continue in that area by looking at fire hazard rooms and areas.While most types of buildings require the protection...


  • Facilities Management & Fire Safety - Content of Fire Training - Part 13

    In LWF’s blog series for those who work in Facilities Management, or who have an interest in or responsibility for Fire Safety, we have been looking at the necessity for staff training and fire drills. In part 12 we looked at the implications of committing to fire safety training in a business or organisation in terms of time commitment. In part 13, the necessary content of the fire safety training sessions is outlined. All comprehensive...


  • Fire Engineering Design and Risk Assessment - Maintenance of Compartmentation - Part 4

    In LWF’s Fire Engineering blogs for Architects and others who work in the building design business, we have been looking at compartmentation of buildings to avoid fire spread from the compartment of fire origin to any other area. In part 3 of this series, the fire-resisting performance of elements which go into comprising a fire-resistant compartment was discussed. In part 4, we discuss how a compartment’s integrity is only as good as its ongoing maintenance,...


  • Facilities Management & Fire Safety - Staff Training & Fire Drills - Part 12

    In LWF’s blog series for those who work in Facilities Management, or who have an interest in or responsibility for fire safety, we have been looking at staff training and fire drills. In part 11 of this series, methods of training were discussed and in part 12, we will continue from that point to discuss the practicalities of who should receive training and how it should be organised.Adequate fire training should be given to...


Case Studies

The Wohl Neuroscience Institute - Fire Safety, Strategy & Engineering
Key Facts: Client: King’s Clinical Neuroscience Institute Project Manager: MACE Ltd Designers: Devereux Architects/Allies and Morrison Approximate Size: 7,400m2 Description of the Project:...

Read more..

General Bulletins

Fire - The External Risk
When we consider fire safety, our focus is normally from within, what can we do to prevent the occurrence of fire and how we can limit its damage.  Whilst this is the correct stance to take, we m...

Read more..

Technical Bulletins

Evacuation Modelling - Factor in Human Behaviour
Evacuation of buildings can be analyzed in different ways. Approved Document B (ADB) which provides guidance on meeting the requirements of the England and Wales Building Regulations with regard to fi...

Read more..

Site map | Web development London