Mike Sutcliffe from Vanquish Hardware protection discusses why fire rated hardware needs protection; what that protection looks like, and what housebuilders and developers need to look out for
Fire doors and fire rated hardware such as locks, latches, hinges, door closing devices, flush bolts, handles, cylinders, eye viewers and letter plates must be manufactured and tested to stringent standards to ensure they operate as intended in the event of a fire.
Essential hardware plays a vital role in the performance of the fire door, for example, fire doors must be held closed by a spring or electrically powered door closer to prevent the spread of flames and heat to adjacent rooms.
Only fully certified doors with a CE Mark, supported with a Field of Application and third-party certification can be classified as fire doors.
Certificated hardware provides proof that the products resist fire during a full-scale fire test, and it is vital that all essential hardware fitted to the fire door is CE/UKCA marked and has been tested to a relevant British or European standard such as BS 476:22 or EN 1634-1, otherwise it will invalidate the fire door certification.
When hardware is rebated into a fire door assembly, however, the integrity and performance of the system is compromised.
Metal locks, latches and hinges function as heat conductors and transfer heat through the timber fire door, which reduces the time it takes for the doorset to reach integrity failure. This should not be the case with a carefully engineered fire safety device that is critical to the fire safety of a building.
PERFECT PROTECTION
All hardware installed on fire doors must be fitted without compromising the integrity of the assembly and this is critical where hardware is rebated into the doorset.
Adding intumescent protection to rebated hardware greatly reduces the rate at which heat transfers through the fire door.
Intumescent protection provides additional insulation around metallic components and helps to resist the transfer of heat from one side of the door to the other. ‘Intumescent’ refers to a material that reacts to high temperatures experienced during a fire and expands to many times its original volume, filling any voids created when rebating for the hardware with an insulating foam.
WHAT KINDS OF INTUMESCENT MATERIAL ARE THERE?
Monoammonium Phosphate is suitable for a wide variety of hardware and expands up to ninety-five times its original volume at temperatures above 350°C with no pressure.
Silicate-based Intumescent has similar expansion and is suitable for up to 120-minute applications. Based on alkali silicates – which begin to swell at temperatures above 100°C – it emits water vapour as it expands which creates a cooling effect and is used in fire door perimeter seals, glazing and penetration sealing of pipes and ventilation elements.
Graphite-based Intumescent features layers of graphite with ionic compounds trapped in between which, upon heating, quickly vaporise forcing the graphite apart. It has an activation temperature of 180°C and expands up to thirty times its original volume to fill any voids from rebating.
For example, highly-flexible and insulating graphite-based intumescent can be extruded and cut into almost any shape and has a working life of more than 100 years. Suitable for up to 120-minute timber fire door applications, such intumescent products can be used to protect a wide variety of hardware; it is not affected by atmospheric moisture and has a strong resultant char that stays in place after activation.
WHAT TO LOOK OUT FOR
Fitting too much intumescence can mean an excessive amount of timber is removed, affecting the door integrity. This means that if a piece of fire rated hardware is not fitted with the specified intumescent, it is not compliant and therefore invalidates its certification.
Currently, there is no market requirement for intumescent hardware protection products to be assessed by an independent third party, which is something that needs to change.
Hardware protection products are not CE or UKCA marked, and it is possible, unless explicitly stated by the hardware manufacturer, for intumescent materials to be swapped out to other brands if they are the same thickness and material type.
For example, ‘graphite intumescent’ is often mentioned in test reports and fire resistance certificates, but it must not be assumed that each brand of graphite-based intumescent is interchangeable. This is because graphite-based intumescent can contain varying quantities and grades of intercalated graphite and expansion ratios and activation temperatures vary between compounds.
It is also unlikely that manufacturers will disclose how much graphite is in their products which makes comparing materials very difficult without a side-by-side test. It is imperative that installers check any test evidence or certification to understand what type and quantity of intumescent is necessary to be compliant.
It is also recommended to only use intumescent that has been independently assessed by a third party which ensures the products have been tested to the relevant standards, and the material will behave consistently and as stated by the manufacturer every time.
Third party certified products also ensure traceability throughout production, so if something goes wrong or there is a problem, it can be traced back to the original source.
Mike Sutcliffe is business development manager at Vanquish Hardware protection