Fire Resistance Rating (FRR) is defined by measuring the ability of a passive fire protection material or systems to resist a standard fire resistance test. It comprises the time (in minutes) for which each of three criteria are satisfied when the element is exposed to the temperature, pressure and applied load specified in the test procedure.
Note that a '2-hour fire rating' is not a complete specification. It has to come in the form of structural adequacy, integrity, and insulation (the three test criteria mentioned above).
It is always presented in that order and it must be three numbers, even if two of them do not apply. Where specific criteria are not relevant, a '–' will be shown. FRR is expressed as xx/yy/zz (i.e. 120/120/120)
Structural adequacy is the ability to support a vertical axial load in case of a fire and only applies to loadbearing elements of a structure. A column or beam may have an FRR of 120/-/-, or a loadbearing wall may have an FRR of 60/60/60.
Integrity is the ability to prevent the passage of flame and hot gases. During the test it is measured by the creation of a gap or ignition of a cotton pad on the non-fire (unexposed) face.
Insulation is the ability to limit the temperature rise on the non-fire (unexposed) face. Do not confuse the meaning of 'Insulation rating' presented here with 'insulation material', which consist of the material usually used in a Passive Fire protection system to increase the insulation rating.
Smoke rating – Is an additional term SM indicating smoke protection. A smoke control door will have an SM added to the FRR, for example, -/60/30 SM.
These terms above are defined in the test standard AS 1530.4-2005 and the unexposed face is sometimes referred to as the 'cold face'.
Testing the fire resistance of elements of building construction
For compliance, these are the applicable standards (product tested to previous versions may no longer be applicable and require to be assessed for equivalence to the current standards):
AS 1530.4-2005 - Methods for Fire tests on Building Materials, Components and Structures – Fire-resistance test of elements of construction
NZS/BS 476.20:1987 Fire Tests on Building Materials and Structures – Method for determination of the fire resistance of elements in construction (general principles).
NZS 4520:2010 - Fire Resistant Door Sets.
AS 4072.1-2005 - Components for the Protection of Openings in Fire Resistant Separating Elements – Service penetrations and control joints.
These tests are often carried out in independent and third-party testing authorities, and results obtained by tests following newer standards are also accepted for compliance (i.e. AS1530.4-2014).
Nelligan Consulting Engineers has an in-house passive fire protection consultant team with expertise and knowledge to assist you with your project at various stages to ensure the passive fire protection installation is appropriately specified, compliant, cost-effective, and with minimal delays.