The term "Passive" fire protection is used to describe products and systems which become part of the construction of the building and which are designed to protect the building's structure and to resist fires within designated compartments to minimize their severity, and to protect neighbouring properties and adjecent occupancies. Additionally, they ensure the safe escape of building occupants in case of fire.

Reaction to Fire
Reaction to fire applies to the behaviour of a material in fire. The behaviour of a material can be classified in terms of:

• Combustibility
• Heat release
• Surface spread of flame
• Ignitability
• Smoke toxicity

Various test standards are referred to in order to measure such reactions to fire.

Resistance to Fire
It applies to an element of construction (a structural member, a ceiling, a partion, a door, a window, a roof, a wall, a floor, etc...), or to an assembly of elements. The design of such building element with its materials and the way that the different materials react and interact when exposed to fire, will provide a desired fire resistance performance.

Certain building materials having a pooer behaviour in fire may be used to form a fire resistance element. The best example is timber which behaves quite differently in fire depending on its density and type of wood.

FIRE TEST STANDARDS - TESTS ON MATERIALS
The standard most commonly referred to in Building Codes is the British Standard (BS 476)

BS 476: Part 4: 1970
Non-conmbustibility test for materials.

This test classifies materials as either 'non-combustible' or 'combustible'. It is the most stringent standard for the fire performance of materials and gives a measure of the heat and flames generated by the material under standard heating conditions. Non-combustible materials can be used without restriction anywhere in a building. Their use ensures that hazards due to smoke and toxic gases are minimized and that the fabric of a building makes no contribution to a fire.

All SOBHA board products are non-combustible


BS 476: Part 6: 1981 or 1989
Method of test for fire propagation for products.

This test measures the amount and rate of heat evolved by the material while subjected to standard heating conditions. Test results are given as an index of performance (i) which is based on three sub-indices (i1,i2,i3). The higher the value of the Index of Performance, i. the greater is the materials contribution to fire growth. The higher the value of the sub-index, i, the greater the ease of ignition and flame spread.

BS 476: Part 7: 1971 or 1987
Method for classification of the surface spread of flame of products.

This test classifies materials into Classes 1 to 4 in descending order of performance according to the rate and extent of flame spread over their surface under standard heating conditions. As all SOBHA board products are non-combustible, they are also accepted as having the highest rating in the surface spread of flame test i.e. Class 1.

3. FIRE TEST STANDARDS - TEST ON CONSTRUCTION SYSTEMS

3.1 Fire testing methods

The Fire performance of any system will vary depending on the heating conditions it is exposed to. Different national and international fire curves have been developed to simulate fires in tests carried out in fire test furnaces, by recognised national organizations as follows:-

1. The standard cellulosic time temperature curve based on ISO.

This curve is used in standards throughout the world (including BS476) as a model of a ventilated controlled natural fire i.e. fires in normal building. The fire temperature increase after 30 minutes is 822°C.

2. The hydrocarbon curve.

This curve is a simulation of a ventilated oil fire with a temperature increase of 1068°C after 20 minutes.

3. The RABT curve.

This is the German guideline for the equipping and operation of road tunnels. The maximum temperature increase is 1200°C over a period which depends on the type of structure.

4. The RWS curve. (Rijkswaterstraat)

This model of an oil fire in an enclosed room has been developed in the Netherlands and is specified in Dutch tunnels. It is Internationnaly accepted. The temperature increase after 60 minus is 1350°C.

3.1 Fire testing performance

"Fire resistance" is not a property of an individual material but is the measure of the performance of a complete element of construction when exposed to the standard heating conditions. The failure criteria of elements of building construction when tested in accordance with British Standard (BS 476: Parts 20-24), are as follows :-

Loadbearing capacity

The ability of a specimen of a loadbearing element to support its test load, where appropriate, without exceeding specified criteria with respect to either the extent of, or rate of, deformation.

Stability

The ability of a ducthwork system to remain in place.

Integrity

The ability of a specimen of seperatin element to contain a fire to specified criteria for collapse, freedom from holes, cracks and fissures and sustained flaming on the unexposed face.

Insulation

The ability of a specimen of a seperation element to restrict the temperature rise of the unexposed face to below specified levels (140°C mean rise, 180°C max rise).

3.3 Fire testing standard

The fire performance standard most commonly referred to in Building Codes in the Asia Pacific region is British Standard (BS 476:Part 20 to 24).

BS 476: Part 20

This part describes the general procedures and equipment required to determine the fire resistance of elements of construction and should be read todether with BS 476: Part 21,22,23 and 24 as appropriate, which describethe detailed procedure for the testing of individual elements of construction. For the purposes of these parts, elements of construction have been categorized into four main groups:
a) Loadbearing elements that have a fire resistance.
b) Non-loadbraring elements that have a fire resistance.
c) Element that make a contribution to the fire resistance of a structure.
d) Ducts designed to prevent fire spread across fire barriers.

BS 476: Part 21. Methods for determination of the fire resistance of loadbearing elements of construction.

This standard describes methods for determining the fire resistance of loadbearing beams; columns; floors, flatroofs and walls. Beams and columns are assessed in terms of loadbearing capacity, whilst floors, flat roofs and walls are measured in terms of loadbearing capacity, integrity and insulation.

BS 476: Part 22. Methods for determination of the fire resistance of non-loadbearing elements of construction.

This standard describes methods for determination of non-loadbearing partitions, doorsets, shutter assemblies, ceiling membranes and glazed elements of construction these are determined with respect to integrity and, where appropriate, insulation.

BS 476: Part 23. Methods for determination of the contribution of components to the fire resistance of a structure.

The standard describes test methods for

a) determining the effective protection that is provided by a suspended ceiling to a standard supporting construction of steel beams and concrete deck; and
(b) determining the contribution of intumescent seals to the fire resistance of timber door assemblies.

BS 476: Part 24. Method for the determination of the fire resistance of ventilation ducts

The general purpose of this standard is to test and measure the ability of a duct assembly to resist the spread of fire from one fire compartment to another. Results are expressed in terms of stability, integrity and where require, insulation.