The LWF Blog

Fire Engineering Design and Risk Assessment – Foam System Components & Testing – Part 8

June 21, 2018 12:04 pm

In LWF’s fire engineering blog series for architects and others in the building design business, we have been looking at types of fire suppression. In part 7, foam system design was discussed including application rates, duration and AMAO. In part 8, the necessary components and materials, testing and documentation for foam systems are raised.


The pipes used to carry foam concentrate and solution should not be made of galvanised metal, as the chemicals will cause corrosion in the pipes. Commonly, black steel piping is recommended, although some concentrates specify the use of steel or copper alloy instead. The standards relating to pipe, fitting and valves are the same as those used for sprinkler systems, as similar operating pressures apply.


It should be noted that all pipework must be supported and undergo pressure testing to 1.5 times the maximum working pressure, after installation.


Upon commissioning, the foam system should undergo tests to ensure it is functioning correctly and following that, the tests should be repeated annually. Where possible, the system should be allowed to discharge foam during testing to establish that the discharge devices are functioning correctly and the required coverage is achieved as planned (cone roof tank foam chambers discharge away from the tank to avoid contamination of the tank itself).


During testing, a foam sample should be taken in order to check that the foam proportioning system has mixed the correct ratio.


While undertaking annual testing, the foam proportioning system should be tested at maximum flow, to check proportioning is accurate. The discharged foam solution should be contained, collected and disposed of in an environmentally correct manner.


While modern foam concentrates have a shelf life of between 10 and 20 years, dependent upon foam time and storage conditions, premix foams have a limited life and should be replaced in their entirety every one to three years.


For this reason, a sample of the foam concentrate should be analysed annually to check it remains effective.


The types of documentation that should be provided with each system are detailed below:


 Scaled plan and section drawing of the hazard and the foam system to include proportioners, proportioner location, piping and discharge devices, valves and pipe hanger spacings.


 An isometric view of the agent distribution piping system which shows the lengths, sizes and node references that relate to the flow calculations.


 Flow calculations, with detail of pipe and nozzle sizes.


 Name of owner of the system and occupant of the building


 The building location, in which the hazard is located.


 The location and construction of the protected hazards.


 Information on the foam concentrate, including the agent used, proportioning concentration and quantity provided.


 The specification of the water and foam supplies used to include capacity, pressure and quantity.


 A description of the occupancy and any hazards protected.


 A description of the discharge devices in use including the orifice size/code where applicable.


 A description of pipes, fittings and valves used including the material specification of each.


Part 9 of this series will move on to look at Gaseous Systems. 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.


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