Protection systems Test conditions are standardised and,
while they provide a means of establishing the fire resistance capabilities of particular products, these conditions are currently only representative of one possible fire exposure condition at the fully developed fire stage. Therefore, they are unlikely to be experienced in a real fire scenario due to the number of variables that affect fire growth, such as fire load, compartment size, ventilation conditions and availability of oxygen. The objective of benchmark fire test
standards is to provide reproducible test conditions (heating and pressure) for construction products, such that their fire resistance can be established in terms of time (eg 30 or 60 minutes) against the criteria of the standard, which can then be used to satisfy the functional requirements of the building regulations. For the reasons given above, this time is a measure of the construction products’ performance at elevated temperatures, but may have little direct relationship with the duration of a real fire. Specialist fire engineers are able to review the appropriateness of such building or site specific conditions, and consider time equivalence and other design criteria under the functional approaches to fire safety design and meeting building regulations. Furthermore, testing only provides
information on the product or system that was tested and any identical replication of such a product or system. As such, it offers
no extension to scope such as alternative configurations, dimensions, and modifications to design – aspects that are likely to be required for different building scenarios and user requirements.
Engineering assessments in lieu of fire tests
(also known as global assessments and field of applications) are documents that are written by competent and experienced engineers in the field of fire testing, structures and materials. These independent professional engineering reports provide scope for interpolating and extrapolating the results achieved in the fire test/s, but the conclusion of the engineering assessment will still be written and quantified in terms of likely fire resistance performance, in minutes, to the relevant fire test standard. The engineering assessment of performance or field of application, and the associated test evidence, can then be used to show compliance with the requirements specified in Approved Document B and other codes of practice such as BS 9999 and the BS 7974 series, which serve to satisfy the functional requirements of the building regulations and are linked to building design. Third party certification of fire resisting
products and systems, as well as specialist installers, offer a greater level of assurance that the fire resisting construction product and system is capable of providing its performance as originally assessed and tested, although this process is not currently mandated in UK building regulations2
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FOCUS
www.frmjournal.com MAY 2018
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