Fire curves & Testing
Testing for protection against fire
A fire is a chemical reaction of a fuel source with oxygen accompanied by the creation of flame, smoke, and a large amount of heat. In fire protection, all three of these need to be guarded against
In many ways Microtherm® is the perfect insulation for use in passive fire protection (PFP) systems. It is non-combustible and it will withstand the extremes of temperature of even a hydrocarbon fire.
Microtherm® can be only one quarter the thickness of conventional insulations for equivalent performance at high temperatures. As a consequence of this, PFP systems based on Microtherm® are generally the thinnest and the lightest available.
Testing for exposure to fire follows the same basic principles all over the world. A test specimen is clamped against a furnace which is programmed to heat up in a pre-defined temperature against time relationship. The performance of the specimen is assessed by measuring the temperatures on the un-exposed face and comparing them with acceptable levels specified in international standards.
Microtherm have in-house fire laboratory facilities capable of testing bulkheads, decks or ceilings, lift shaft access doors, as well as fire safes and fire protection enclosures.
There are two main temperature / time fire relationship curves in common use for building and passenger transport PFP system evaluation.
Cellulosic curve
The Cellulosic curve, also known as the "A" category fire curve, is the least intense of the fire curves and covers the basic scenario of a fire of general combustible items such as the furniture and contents of a building and its materials of construction.
ISO 834-8:2002 Fire Resistance Tests – Elements of building construction – defines it by the relationship –
T = To + 345log10 (8t+1)
where
t is time (min)
T is the furnace temperature (°C) at time t
To is the initial furnace temperature (°C)
Confidence in testing
Hydrocarbon curve
The Hydrocarbon curve, also known as the "H" category fire curve, is much more intense than the Cellulosic curve and reaches 1000 oC (1832 oF) in around 7 minutes. As the name implies, it represents combustion of hydrocarbons for applications such as aviation and vehicle fuel fires and fires in the offshore industry.
ISO 834 (HC) defines it by the relationship –
T = To +1080 (1-0,325 e-0,167*t-0,675 e-2,5*t)
where
t is time (min)
T is the furnace temperature (°C) at time t
To is the initial furnace temperature (°C)
Confidence in testing