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



Navigation

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

Lawrence Webster Forrest
Legion House
Lower Road
Kenley
Surrey
CR8 5NH

Tel: +44 (0)20 8668 8663 Fax: +44 (0)20 8668 8583
E-mail: fire@lwf.co.uk

Fire Engineering Design and Risk Assessment - Water Mist Systems - Part 14

Posted by LWF: 31/07/2018 12:11

In LWF’s Fire Engineering blog series for Architects and others in the building design business, we have been looking at Water Mist Systems. In part 13, the basic principles behind the use of very fine water droplets to fight fire were considered. In part 14, system configurations and the different types of water mist system will be discussed before moving onto system design.

 

Water Mist System Configurations

A water mist system can share certain characteristics with a sprinkler system. For example, a water mist system can be configured to use frangible bulb elements (which fracture when a certain temperature is reached. This allows for only those release nozzles in close proximity to a fire to activate. 

Alternatively, a system may be designed with all of its nozzles open, so that water mist is discharged from every head when the system becomes active.
A water mist system can be used to protect an enclosed space, in the same way that a gaseous system might be used, or to provide protection on a local level to a particular hazard within a larger space.

The water supply for a water mist system can be taken from mains water, where appropriate, but can also be taken from pumped water supplies, such as potable, sea-water or cylinders containing water which purge under gas pressure.


Types of Water Mist System

A water mist system will be classified as high, intermediate or low pressure, according to their operating pressures. An operating pressure can indicate various differences in system type, such as the method of generating water droplets, the droplet size ranges and the mechanism used to give momentum to the water droplets.

High-pressure systems operate at pressures above 80bar, intermediate systems at pressures between 15bar and 80bar and low-pressure systems operate up to 15bar.


System Design

Water mist system designs are based upon the full-scale fire testing of fuels and hazard configurations which are similar to the environment needing protection.
Each manufacturer of water mist systems will produce a unique design for a particular hazard which is specific to that manufacturer’s fire test results. The performance produced will be a functional combination of the unique nozzle operating parameters, the enclosure or area, the type of fire and the ventilation available.

In cases where water mist systems are requested for conditions where relevant test data cannot be provided, fire tests must be carried out to provide the design basis and prove validation of the approach.

The design and installation of water mist systems should only be permitted by those organisations with direct access to and understanding of fire test data and a proven knowledge of the technology.


In part 15 of this series, LWF will look at the components that comprise a water mist system. 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

  *

  *

 


CAPTCHA Image

[ Change the image ]


*Required

Subscribe to our fire safety blogs

Bulletins
Email Format
* indicates required

FIRE SAFETY BLOGS

  • Fire Engineering Design and Risk Assessment - Compartmentation & Fire Severity - Part 10

    In LWF’s Fire Engineering blog series for Architects and others in the building design industry, we have been looking at the use of compartmentation to avoid the spread of fire. In part 9, the use of compartments with sprinkler systems was discussed and in part 10, we look at the potential severity of fires in enclosed spaces.The severity of a fire in an enclosed space is dependent upon factors such as heat leaving the...

    Read more...

  • Fire Safety for Healthcare Premises - Sprinklers - Part 44

    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 43 of this series, we discussed cavity barriers and those areas where they are not practical for use, for fire safety reasons. In part 44, we move on to discuss the use of sprinklers in healthcare buildings. Sprinklers are not a requirement for patient areas of healthcare buildings...

    Read more...

  • Facilities Management & Fire Safety - Fire Safety Engineering - Part 1

    In LWF’s blog series for those who work in Facilities Management or who have an interest in or responsibility for fire safety, we were looking at fire safety training. In Part 1 of this series, however, we begin to review the subject of fire safety engineering. While most people reading on this subject could work out what fire safety engineering is, from the title, LWF will start by looking at the history of fire safety...

    Read more...

  • Fire Engineering Design and Risk Assessment - Compartmentation & Sprinklers - Part 9

    In LWF’s fire engineering blog series for Architects and others in the building design business, we have been looking at compartmentation and how can be used both in prescriptive and fire engineered solutions. In part 8 of this series, the provision of a fire safety strategy for a building was discussed and in part 9, we move onto how compartmentation and sprinklers work together.The effectiveness of sprinkler systems at controlling fires has had a...

    Read more...

  • Fire Safety for Healthcare Premises - Cavity Barriers and Sprinklers - Part 43

    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 42 of this series, we looked at how cavity barriers should be installed in uninterrupted concealed spaces or cavities and also some exceptions to the rules. In part 43, we will continue looking at the use of cavity barriers in healthcare buildings.There are some instances where cavity...

    Read more...

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