BS 8414-2:2020 pdf download – Fire performance of external cladding systems Part 2: Test method for non‑loadbearing external cladding systems fixed to, and supported by, a structural steel frame
5.2Structural steel test frame
The structural steel test frame shall be designed and constructed to withstand the expected loadingimposed by the system under test and any subsequent distortions that can occur during the testprogramme.All details shall be recorded.
NOTE AnnexB shows a typical structural steel test frame (see Eigure B.1).The test specimen installation mightneed modification of, or additions to, an existing base test frame.
5.3 Main test apparatus wall (main face)
The main test apparatus wall onto which the test specimen is applied shall be:
a) vertical, extending (7 700 ±100) mm above the top of the combustion chamber opening; and
b) at least 2 600 mm wide.
5.4 Return wall (wing)
The return test apparatus (wing) wall onto which the test specimen is applied shall be:
a) vertical, of the same height as the main test wall;
b)at least 1 500 mm wide; and
c)perpendicular to the main test apparatus wall.
5.5Combustion chamber
The combustion chamber shall be constructed in accordance with the dimensions shown in Figure 1,including the provision of a robust lintel across the head of the chamber opening and a solid platformable to support the heat source.T’he combustion chamber shall be capable of enduring the effects ofthe test procedure without itself suffering undue damage or distortion.
NOTE A nominal cross-section of 200 mm × 200 mm produced from C25/30 grade concrete has been found toproduce a suitable lintel.
The combustion chamber shall be positioned at the base of the vertical main test apparatus wall andfully sealed to prevent air ingress, except for an opening such that the fire can project through theopening at the base of the vertical main test apparatus wall.
The top of the chamber opening shall be (2 000 ±100) mm above the base of the test facility and shallbe (2000±100) mm wide.
A distance of (260±100) mm shall be allowed from the side of the opening of the combustion
chamber to the finished face of the test specimen under test (see Figure 1).A timber crib heat source(5.6) shall be installed within the combustion chamber.
5.6Timber crib heat source
The timber crib heat source shall be as specified in Annex A.5.7Thermocouples
All thermocouples shall conform to BS EN 60584-1:2013,Type K (Chromel/Alumel).The thermocouples shall be mineral insulated and have a 1.5 mm (nominal) diameter with insulated
junctions.At each specified level, temperatures shall be monitored using thermocouples positioned in accordance with 5.7.2 and 5.7.3.
5.7.2 External thermocouples General
External thermocouples shall be positioned to a tolerance of ±10 mm with the hot junction positioned(50 5) mm in front of the face of the test specimen. thermocouples at levels 1,2 and 3
External thermocouples shall be located at levels 1,2 and 3 on the test specimen as follows(see Figure 2).
a) Thermocouples shall be positioned in front of the main test wall face on the centre line and
at 500 mm and 1 000 mm each side of the centre line of the combustion chamber (five locations).
b) Thermocouples shall be positioned in front of the wing test wall face, at 150 mm, 600 mm and
1 050 mm from the finished face of the main test wall face (three locations).
NOTE Levels 1, 2 and 3 are meant to represent floor spacing in a building.The results obtained from levelsat the distances above the combustion chamber opening stipulated in Figure 2 are valid for greater floorseparation distances.
5.7.3 Internal thermocouples
Internal thermocouples shall be positioned at level 2 and level 3 only to a tolerance of ±10 mm inaccordance with and Figure 2 and clear of any cavity barrier.
NOTE For cases where the cavity barrier coincides with thermocouples at level 3 (i.e.7 500 mm above the top ofthe combustion chamber), the edge of the slab should be moved downwards to allow the cavity barrier to be fixed atleast 50 mm below the thermocouples.BS 8414-2 pdf download.