The LWF Blog
Fire Safety for Facilities Management Personnel – Fire Extinguishing Systems – Part 254
May 28, 2024 10:53 amLawrence Webster Forrest (LWF) is a specialist fire engineering and fire risk management consultancy whose aim is to give information on best practice in fire safety for facilities management personnel through this blog series. In part 253, LWF discussed items on the list of components of a typical gaseous extinguishing system. In part 254, we talk about wet chemical systems and powder systems.
Wet Chemical Extinguishing Systems
A wet chemical system for extinguishing fire is generally only used in kitchen areas which can be as small as a hotel kitchen, or as large as an industrial unit for food production. They are designed to protect from fires resulting from deep fat fryers and use similar saponification agents to those used in Class F fire extinguishers which are also designed for fires fuelled by cooking oils and fats. They contain a large amount of potassium salts, amongst other, lesser, ingredients. They work by creating a barrier between the fire and oxygen, which suffocates the fire.
There are two recognised standards for wet chemical systems:
Fire insurers now often require such systems to be in place in particular premises as a condition of insurance.
Powder Extinguishing Systems
A dry chemical fire suppression system is a type of fire protection system which has a large tank filled with dry chemical powder that is then pressurised for release over an area. In principle, they are suitable for total flooding or local application in areas with either Class A or Class B risks.
Powder systems are rarely seen in practice, but when they are used it is mainly for local application to cover Class B risks (flammable liquid fires). They have also been popular to cover specialised Class A risks, such as textile machines. They may also have been used for other Class B risks such as road tanker filling bays.
BS EN 12416-2:2001 Fixed firefighting systems. Powder systems – Design, construction and maintenance contains guidance on the design of powder systems.
In part 255 of this series, LWF will look at Aerosol Systems and Oxygen Reduction Systems. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact LWF on freephone 0800 410 1130.
Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 35 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.
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.