FOCUS
Toxicity threats
seen issuing from the top of the system and therefore is bypassing the open state cavity barriers, which would not yet have activated. Therefore, within minutes of the fi re the fl ats
above could be fi lling up with smoke, but we have no idea how quickly, or what that smoke contains. At the very end of the test, some 30 minutes after the crib has been extinguished, smoke is still seen issuing from the top of the wall. None of these observations appear in the classifi cation report, which reads: • 5.30 – Smoke seen issuing from gap between panels 1 and 6, 2 and 7
• 6.58 – Smoke seen issuing from top of system behind panels 2 and 3
• 60.00 – Test ended, residual burning near panel 13 extinguished. Face of test wall doused down as smoke was still issuing from top of test wall
Figure 6: MHCLG July 2018 HPL BS 8414 post test.
pressure laminate (HPL) materials in the large scale testing programme. The heat release rates of HPL materials2
are much lower than combustible
aluminium composite material (ACM) (see Figure 5 on page 27). It’s hard to argue that polyethylene cored
ACM is not in a danger category of its own, and it could be expected that the speed of the spread of fi re would be lower with HPL materials. Indeed, this is evidenced by the narrow pass of a fire retardant (FR) HPL and mineral wool BS 8414 test performed by the government last July. However, Figure 4’s table shows that the total fuel stored in the HPL material is much greater per square metre of cladding than any of polyethylene (PE), FR or non combustible ACM materials (NC) (see Figure 4 on page 27). Therefore, the capacity of HPL to produce smoke
during a fi re is perhaps signifi cantly greater than ACM with little difference between FR and standard variants. As you can see from the rig after the test (in Figure 6 above), a large area of fire retardant HPL has been consumed or has detached during the test. The classifi cation report does not mention smoke produced during the test. The test report, which a facade engineer is even less likely to see due to commercial confi dentiality, makes very limited references to smoke during the test – but questions are raised for a facade or fi re engineer. Early in the test, smoke is apparently
28 MARCH 2020
www.frmjournal.com
This is an unacceptable lack of information and a missed opportunity during an expensive test to collect data vital to the fi re safety comparison of facade systems. Figure 7 below shows a non combustible brick slip system after a BS 8414 test. Although some bricks near the crib have detached as the aluminium mounting system has melted, no cladding material has been consumed. Yet the classifi cations of the MHCLG HPL system which nearly failed – and this one, which was largely undamaged – will appear essentially the same to a client or facade engineer.
Figure 7: Non combustible clay slip BS 8414 post test.
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