Protection from Heat & Fire

While it is possible to have intense heat without fire and vice versa, generally the two go hand-in-hand. Fabrics which offer suitable protection exclusively for one often do not offer protection for the other.

Heat Barrier Rating

Protection from heat relates to two factors, the type of fabric used to provide the protection, and the weight and thickness of that fabric. It is generally conceded that a fabric that is light in weight will not be able to provide adequate insulation against heat, however the amount of protection given can vary quite considerably within the same weight range, depending on the make-up of the fabric.

TPP (Thermal Protective Performance)

TPP is the measure used to rate heat protection. In the TPP test, flame, radiant heat or a combination of the two, are applied to one side of a fabric sample while a sensor on the other measures the heat transference through that fabric. When the heat registers the equivalent of a second-degree burn, the measurement is calculated as calories per cm2. This constitutes the fabric's TPP.

Flame Barrier Rating

A fabric flame barrier must demonstrate that it will not support or promote flame when exposed to a fire source. It is also essential that the fabric does not melt or break down when exposed to fire, rendering itself ineffectual as a barrier, thereby causing damage to underlying skin.

Flammability tests on fabrics may differ slightly, but commonly they involve the fabric being exposed to an open flame for a pre-determined period. At the end of the exposure time the damage to the fabric is assessed and a flame barrier rating allocated to it.

Molten Metal Splash Rating

The splash risk from molten metal is a major factor in the performance of protective fabrics.

Fabrics are rated on:

• The speed with which they can shed molten metal, thus reducing the exposure risk to the heat of the metal.
• The ability to provide burn protection to the underlying skin as the molten metal is being shed.
• Their resistance to ignition through exposure to the heat generated by the molten metal.

Shedding of molten metal

Molten metals require careful evaluation to ensure the correct option is taken regarding protection. Different metals have different characteristics and will stick to many fabrics.

Molten metal splash shedding tests utilise the relevant metal for the industry the fabric is intended for use in. The fabric being tested is laid over a layer of simulated skin and these are then set at an angle to allow shedding to occur. The metal splash index is calculated on the amount of molten metal that can be poured on the fabric until the imitation skin layer underneath registers damage.