The Testing Process
Fire resistance for fire doors is certified through rigorous fire testing. Fire door manufacturers must obtain certifications through a United Kingdom Accreditation Service: an unbiased third party that ensures credibility to the process and full compliance with fire door regulations.
The manufacturer or designer submits a specimen (a door sample, actually) to the testing organisation. The testing consists of mounting the product into suitable structural surroundings and performing the destructive testing described below.
The scope of the testing depends on what the manufacturer needs to consider to meet marketing requirements or hardware and glazing variations for fire doors with glass. For example, a fire door for a toilet facility would require a lower level of fire resistance than, say, a glazed fire door to a flammable materials storage area.
The Test of Time
Internal fire doors are tested and graded in terms of time. The fire resistance time is the relationship between the door’s exposure to a fire and the temperature reached before the door fails. That time is measured by exposing the door in a test furnace until the door fails.
Simulating Real Fire Conditions
British standard performance fire door tests simulate the actual intended use of the fire door. One side of the fire door is exposed to a flame while technicians closely monitor the effects of heat on the door’s integrity, structure, and sealing capabilities.
For the test, the specimen door is built into a supporting construction and mounted into a fire door frame. The furnace flame is set to a time and temperature standard. The latter is combined with a pressure condition that simulates the point at which everything in the compartment has been ignited—or the so-called post flashover condition.
In an actual fire, the flashover time will depend on the shape of the compartment, its ventilation, combustibles, etc.
In the above example of the toilet facility door versus the door to a flammable liquids storage room, fire growth periods would be radically different. So, the testing does not consider fire growth periods, because, as previously stated, the flashover times are variable.
The testing times begin from a baseline of flashover, rather than the growth period of the fire. That testing proceeds for a required duration of 30, 60, 90, 120 minutes, or longer, until the fire door material fails. Failure consists of loss of integrity, destruction or insulation, and heat radiation as determined by:
-Observing sustained combustion or more than 10 seconds on the non-fire side of the door
-Ignition of cotton pad material on the non-fire side of the door by gasses escaping the fire door seal
-Measuring insulation failure when insulation temperature reaches 180 degrees
-Measuring total heat flux radiation by means of a heat flux radiometer positioned 1m distant from the tested fire door material
Key Notes for Specifiers:
For the specifier, we have compiled a list of key considerations in regard to the fire testing procedure:
-To determine the fire resistance time, a doorset is exposed to a ‘standard’ fully developed fire in a test furnace until failure occurs according to certain criteria.
-This ‘standard’ fire condition used in tests is defined by the relationship between the duration of the fire and the temperature reached.
-The Building Regulations and most fire protection/prevention codes call for a minimum performance with respect to integrity.
-There are some requirements regarding radiation effects and insulation to resist the rise in unexposed face temperature. Individual specifiers or insurance requirements may call for doors with specified levels of performance.
-At present, specifiers have two choices for testing fire resistance – BS 476 (the British Standard method) or BS EN 1634 (the European Normative method).
-Harmonised product standard BS EN 16034 covers the fire and smoke performance characteristics of fire resisting doorsets. BS EN 16034 is likely to be published in 2015 and, after the co-existence period, it will be an offence under the Construction Products Regulation to place a fire-resisting doorset on the open market without a CE mark.
Fire resisting doorsets must also comply with the essential characteristics listed in the relevant part of BS EN 14351, depending on whether the door is for internal or external use. The length of the co-existence period of the National and European route to market, after BS EN 16034 has been published is yet to be determined.
-Changes to a construction tested under the British or European Standards will require another fire test, an assessment of performance, a Direct Field of Application (DIAP), or an Extended Field of Application (EXAP).
-Doorsets are also tested to evaluate their ability to control smoke.
-It is becoming increasingly difficult to identify fire-resisting doors simply by weight and thickness.
-New materials and methods of construction have led to the production of thinner and lighter fire-resisting doors.
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