Extrusion is a process where the material goes through plastic deformation through the application of force causing the material to flow through an orifice or even a die which is a circular steel disk which contains openings that can create a profile. During the extrusion process the material, in this case, silicone rubber will adopt the cross-section of the die. The extrusion process helps to create an excellent finish to the material and also gives freedom of form in the eventual design process.
Silicone rubber is one of the most popular material choices for a huge number of industries when it comes to extrusions. Fire safety is among the industries where silicone rubber seems to be the go-to, and this is for a number of reasons. Standardised silicone has many benefits that can help with fire safety, however, there are two main types of silicone that are used when thinking about fire safety.
Two types of fire retardant silicone extrusions
There are actually two different types of extrusions that are used for fire safety. Heat-resistant silicone extrusions and flame retardant silicone extrusion are often confused with each other, however, they both have completely different properties.
Heat Resistant Silicone
Heat-resistant silicone is one of the two types of silicone extrusions that are predominantly used for fire safety. This is because it is manufactured to function properly and maintain its mechanical properties when met with extreme temperatures, both hot and cold.
The rubber material can withstand heat up to 305°c all the way down to -70°c, which is a far greater range than any other polymerised rubber material. Its ability to withstand such incredible temperatures allows the material of the structure to maintain its properties when met with any temperatures meaning that it can perform at its best in any environment.
A good example of a heat-resistant silicone extrusion would be a silicone seal used on an oven. This is constantly exposed to extreme heat but can still perform extremely effectively due to its incredible temperature range.
Flame Retardant Silicone
As you would expect from the name, flame retardant silicone extrusions are also commonly used in fire safety. Flame retardant silicone is so effective as it has been specifically formulated to have the ability to be self-extinguishing, something that no other material has. For a material to be classified as flame retardant it must go through stringent testing and must be subjected to a flame for a specified period to prove that it can perform correctly even when met with flames.
This silicone rubber also has low smoke and low toxicity. Therefore, in the event of a fire, they will not emit much smoke or toxic fumes. This is actually a very important safety standard in many industries that commonly use silicone rubber extrusions.
However, flame retardant silicones do not have the ability to withstand such impressive heat ranges as heat-resistant silicone extrusions. These can only withstand temperatures of up to 200°c. This is still impressive when compared with other rubber materials.
Flame retardant industry grades
There are multiple silicone grades that meet flame retardant requirements for different industries. These include:
VFR(2) – This is a flame retardant grade of silicone developed for rail applications. It is available in 68° Shore A.
VFR 203-803 – This flame-retardant grade of material is specified for use in aerospace applications and is available from 20° shore A to 80° shore A.
EN45545-2 – This particular garde is standard in the railway industry and across other mass transit vehicles.
The importance of fire safety silicone extrusions
In certain industries’ working environments there are always potential dangers, with fires being one of them. When dealing with applications that go through extreme temperatures or things like sparks that could be a fire hazard, silicone rubber is undoubtedly one of the best materials for thighs such as extrusions to be made from.
Silicone is an extremely effective and safe material, which is why it is extremely effective to have silicone rubber extrusions bridging the components together in moving parts and machinery that could potentially be susceptible to fire hazards. The material also has the unique ability to help stop the spread of things such as toxic gas, smoke and fire that could pose a serious threat to workers.
