Summary
Metalline is a fabricator of specialist architectural metalwork in the UK, producing architectural fabrications in a range of materials for the architectural and building sector. Metalline has created a fire detection system to be retrofitted into existing cladding with the intention of giving a faster reaction time than waking watch. To investigate the response time of their cladding fire detectors, they carried out a bespoke fire test at the FPA’s cladding test rigs in Gloucestershire.
Challenges
The problem of unsafe cladding left hundreds of buildings at risk of fire right across the UK. Government figures from 2023 show that progress has been made in remediating buildings, but as of January 2023 there were still 81 high-rise residential and publicly owned buildings that have ACM cladding systems unlikely to meet Building Regulations in England. As legislation and funding programmes change, more buildings are coming into scope of remediation.
The Greater London Authority estimates that the introduction of the new 11-18 metre fund may cover an additional 3,000 buildings in London alone that are eligible for remediation funding. In the meantime, the residents and users of these buildings have been left to rely on often costly alternative fire protection measures, including waking watches.
It was with this in mind that Metalline began to look at ways in which adequate fire safety for these buildings could be provided more cost effectively which led them to create their fire detection system designed to monitor the façade using three different sensors on the cladding system – a smoke sensor in the cavity, a heat sensor in the cavity, and a heat sensor on the outside.
To investigate the response time of these sensors, Metalline approached the FPA to design and carry out a bespoke fire test to assess the performance of the system, examine how best to monitor the system and the spread of smoke, and establish how to insert the sensor into the cladding system without compromising the integrity of the system.
How the FPA helped
Metalline worked closely with the FPA’s Testing team to design a test that would address these challenges. The testing was carried out on a specially constructed 10m wide and 9m high test rig at the FPA’s facilities to assess the detector response times across two 4.5m stories, with detectors located at the edge of cavities.
The worst-case scenario for a fire is with the most combustible cladding. However, the worst-case scenario for fire detector response time is with the least combustible cladding. Therefore, the majority of the test rig was constructed with non-combustible aluminium with mineral wool insulation. 5 ACM panels were used in the bottom left-hand corner of the test rig to serve as the main fuel source to assess the detector response times.
Two types of sensors were installed in each test location: a heat detector and a smoke detector, with the majority installed to detect inside the cavity between the aluminium and the mineral wool, positioned on the internal face of the cladding. An additional sensor was positioned externally above the fire and an A2-rated fire-protected sealant was used to seal the holes made to place the sensors.
Results and future plans
Two tests were conducted on the test rig, with a fire positioned in one corner to assess the fire detector response times. The sensor activation times were measured relative to when the fire broke through the cavity. The test as designed defined cavity breakthrough as when either of the cavity thermocouples read 200 °C above the ambient temperature for over 30 seconds.
- The smoke detectors simulating a 10m wide cavity activated before the fire the broke into the cavity, whilst the smoke detectors simulating a 20m wide cavity activated within 1 minute and 5 seconds of fire breaking into the cavity.
- The heat detectors simulating a 10m wide cavity activated within 2 minutes and 21 seconds of fire breaking into the cavity. The heat detectors simulating a 20m wide cavity did not all activate before the test was terminated, 15 minutes after the fire was ignited. However, the first detector located on the upper floor activated within 1 minute and 50 seconds of fire breaking into the cavity for both tests.
- The external heat detector reacted more slowly than the corresponding internal heat detector during both tests, despite being closer to the fire.
Darron Brough, Managing Director of Metalline said: “The safest option is to have an internal detection system in case a fire starts inside, but our thinking was that you also need an external system because if it is the façade that is on fire, that heat sensor won’t alert anybody until the fire has got into the building through a window. Developing this detection system through our subsidiary company, Intelliclad, gave us the means to address this issue, but we needed to be able to prove its safety and reliability when a fire breaks out. The FPA team helped us to design and execute a test to demonstrate the response time of the system and the test results show how quickly our sensors reacted to the fire. The test results prove that our system works – it is a viable product.”
Ryan Brough, Head of Operations at Intelliclad said: “Prior to coming to the FPA, we did a test fire in the car park at our site to understand how we would be able to install our system but the location of the sensors during the test was integral so that we could see the spread of the heat and the smoke. That was when we decided to carry out a full-scale fire test with the FPA’s expertise which we needed to determine how to execute the test, what fire source to use, and how to build the testing rig to most effectively simulate a real-life scenario. The test results proved the reliability of our application and allowed us to go on and win two national awards: Innovation of the Year at the National Building and Construction Awards 2022, and Smart Technology of the Year at the London Construction Awards 2022.”
George Edwardes, Technical Steering Group Manager at the FPA said: “At the FPA we pride ourselves on our ability to design, build and carry out bespoke fire testing so that our customers can assess how their system will perform in a fire situation. We were pleased to work with Metalline to develop a reasonable worst-case scenario for testing their fire detection system to demonstrate the response time of the detectors. This was an interesting project because we had to find the appropriate balance for developing a reasonable worst-case scenario in the absence of an appropriate fire test standard for this type of product. We discovered that the internal detector operated more quickly than the external detector in this scenario and it was critical to identify that the internal detectors had the potential to operate before any of the cavity barriers activated.”
Find out more about the FPA’s bespoke fire research and testing.