ICS 13.220.50; 91.060.01; 91.100.01  
 
Reference number
DRS 540: 2023
© RSB 2023
  
 RWANDA 
STANDARD  DRS 
540 
1.1  
First edition  
2023-mm-dd  
1.2  
Reaction to fire tests for building products 
— Building products excluding floorings 
exposed to the thermal attack by a single 
burning item 
 
   
DRS 540: 2023 
©RSB 2023- All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition 
 
 
 
 
 
 
 
 
© RSB2022 
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from RSB. 
Requests for permission to reproduce this document should be addressed to: 
Rwanda Standards Board 
P.O Box 7099 Kigali-Rwanda 
KK 15 Rd, 49 
Tel. +250 788303492 
Toll Free: 3250 
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw  DRS 540: 2023 
iii                ©RSB 2023- All rights reserved 
 Contents Page 
Foreword ............................................................................................................................................................ vi  
1 Scope ...................................................................................................................................................... 1  
2 Normative references ............................................................................................................................ 1  
3 Terms and definitions ........................................................................................................................... 1  
4 Test facility ............................................................................................................................................. 3  
4.1 General ................................................................................................................................................... 3  
4.2 Test room ............................................................................................................................................... 3  
4.3 Materials ................................................................................................................................................. 6  
4.4 Test apparatus ....................................................................................................................................... 6  
4.5 Smoke exhaust system ......................................................................................................................... 8  
4.6 General measurement section equipment .......................................................................................... 9  
4.7 Other general equipment .................................................................................................................... 10  
5 Test specimen ...................................................................................................................................... 11  
5.1 Dimensions of specimen .................................................................................................................... 11  
5.2 Mounting of specimen ........................................................................................................................ 11  
5.2.1 Mounting as in end use application .................................................................................................. 11  
5.2.2 Standard mounting .............................................................................................................................. 11  
5.3 Installation of the specimen wings in the trolley ............................................................................. 13  
5.3.1 The specimen wings shall be placed in the trolley as follows: ...................................................... 13  
5.4 Number of specimens ......................................................................................................................... 14  
6 Conditioning ........................................................................................................................................ 14  
7 Principle ............................................................................................................................................... 15  
8 Test procedure ..................................................................................................................................... 15  
8.1 General ................................................................................................................................................. 15  
8.2 Testing operations .............................................................................................................................. 15  
8.3 Visual observation and manual recording of data ........................................................................... 16  
8.3.1 General ................................................................................................................................................. 16  
8.3.2 Pre-test conditions .............................................................................................................................. 16  
8.3.3 Lateral flame spread on the long wing .............................................................................................. 17  
8.3.4 Flaming particles or droplets ............................................................................................................. 17  
8.3.5 End of test conditions ......................................................................................................................... 18  
8.3.6 Recorded events .................................................................................................................................. 19  
8.4 Automated recording of data ............................................................................................................. 19  
8.5 Early termination of test ..................................................................................................................... 20  
9 Expression of results .......................................................................................................................... 20  
10 Test report ............................................................................................................................................ 21  
Annex A (normative)  Calculation precedures .............................................................................................. 23  
A.1 General ................................................................................................................................................. 23  
A.1.1 General remarks .................................................................................................................................. 23  
A.1.2 Calculations to be performed on the test data ................................................................................. 24  
A.1.3 Calculations to be performed on calibration data ........................................................................... 24  
A.1.4 Standard data set ................................................................................................................................ 24  
A.2 Synchronization of data ...................................................................................................................... 25  DRS 540: 2023 
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 A.2.1 A............................................................................................................................................................ 25  
A.2.2 O2 and CO2 synchronization with Tms. ........................................................................................... 25  
A.3 Checking equipment response ......................................................................................................... 26  
A.3.1 Temperature readings ........................................................................................................................ 26  
A.3.2 Drift in gas concentration measurement .......................................................................................... 27  
A.3.3 Drift in light attenuation measurement ............................................................................................. 27  
A.4 Exposure period.................................................................................................................................. 27  
A.5 Heat output .......................................................................................................................................... 28  
A.5.1 Calculation of heat release rate (HRR) ............................................................................................. 28  
A.5.2 Calculation of THR(t) and THR600s .................................................................................................. 32  
A.5.3 Calculation of FIGRA0,2MJ and FIGRA0,4MJ (fire growth rate indices) ....................................... 32  
A.6 Smoke production .............................................................................................................................. 34  
A.6.1 Calculation of smoke production rate (SPR) ................................................................................... 34  
A.6.2 Calculation of TSP(t) and TSP600s ...................................................................................................... 37  
A.6.3 Calculation of SMOGRA (smoke growth rate index) ....................................................................... 38  
10.1.1 A.7Calculations for calibrations – Propane heat release ............................................................... 39  
Annex B (normative)  Conditioning procedures and general rules for selection of substrates ............. 41  
B.1 Conditioning procedures ................................................................................................................... 41  
B.1.1 General ................................................................................................................................................. 41  
B.1.2 Conditioning to constant mass ......................................................................................................... 41  
B.1.3 Conditioning for a fixed period ......................................................................................................... 41  
B.2 General rules for selection of substrates ......................................................................................... 42  
B.2.1 General ................................................................................................................................................. 42  
B.2.2 Standard substrates for floorings ..................................................................................................... 42  
B.2.3 Standard substrates for construction products excluding floorings ........................................... 43  
Annex C (normative)  Thermocouple designations ..................................................................................... 44  
C.1 Thermocouple designations .............................................................................................................. 44  
C.2 Thermocouple tolerances .................................................................................................................. 51  
Annex D (informative)  Precision of test method ......................................................................................... 53  
D.1 General remarks and results ............................................................................................................. 53  
D.2 Calculation of test results .................................................................................................................. 55  
D.3 Statistical analysis .............................................................................................................................. 56  
D.4 Statistical results ................................................................................................................................ 56  
Annex E (informative)  Calibration procedures ............................................................................................ 63  
E.1 Procedures for separate pieces of equipment ................................................................................ 63  
E.1.1 General ................................................................................................................................................. 63  
E.1.2 Oxygen analyser adjustment ............................................................................................................. 63  
E.1.3 Oxygen analyser output noise and drift ........................................................................................... 63  
E.1.4 Carbon dioxide analyser adjustment ................................................................................................ 64  
E.1.5 Light system calibration .................................................................................................................... 64  
E.2 System response calibrations ........................................................................................................... 65  
E.2.1 Burner switch response time ............................................................................................................ 65  
E.2.2 Burner heat output step calibration .................................................................................................. 68  
E.2.3 Heptane calibration............................................................................................................................. 73  
E.2.4 Velocity profile factor kt,v ................................................................................................................... 75  
E.2.5 Flow factor kt ....................................................................................................................................... 77  
Annex F (informative)  Calibration procedures ............................................................................................ 78  
F.1 Procedures for separate pieces of equipment ................................................................................ 78  
F.1.1 General ................................................................................................................................................. 78  
F.1.2 Oxygen analyser adjustment ............................................................................................................. 78  
F.1.3 Carbon dioxide analyser adjustment ................................................................................................ 78  
F.1.4 Check of propane mass flow controller ........................................................................................... 79  DRS 540: 2023 
v                ©RSB 2023- All rights reserved 
 F.1.5 Optical filter check .............................................................................................................................. 79  
F.2 Check of the thermal attack on the specimens ................................................................................ 80  
F.2.1 General ................................................................................................................................................. 80  
F.2.2 Procedure ............................................................................................................................................. 80  
Annex G (informative)  Design drawings ....................................................................................................... 82  
Annex H (informative)  Data file format ........................................................................................................ 118  
Annex I (informative)  Record sheet ............................................................................................................. 122  
 DRS 540: 2023 
©RSB 2023- All rights reserved                  vi 
 Foreword 
Rwanda Standardsarepreparedby Technical Committees and approved by Rwanda Standards Board (RSB) 
Board of Directors in accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards. 
The main task of technical committees is to prepare national standards. Final Draft Rwanda Standards 
adopted by Technical committees are ratified by members of RSB Board of Directors for publication and 
gazettment as Rwanda Standards. 
DRS540 was prepared by Technical Committee RSB/TC 9, Civil engineering and Building materials.  
In the preparation of this standard, reference was made to the following standard: 
BS EN 13823:2020: Reaction to fire tests for building products - Building products excluding floorings exposed 
to the thermal attack by a single burning item 
The assistance derived from the above source is hereby acknowledged with thanks. 
Committee membership  
The following organizations were represented on the Technical Committee on Civil engineering and Building 
materials (RSB/TC 9) in the preparation of this standard. 
A+Construction Group Ltd 
Africeramics Ltd 
Consultants Engineers Group (CEG) Ltd 
D&D Resources Ltd 
Dutureheza Ltd 
Enabel Rwanda 
Greenpack Africa Ltd 
Integrated Polytechnic Regional Centre (IPRC) - Musanze  
Mass Design Group 
NP Construction Company (NPCC) Ltd DRS 540: 2023 
vii                ©RSB 2023- All rights reserved 
 Road Transport Development Agency (RTDA) 
Rwanda Housing Authority (RHA) 
Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA) 
Rwanda Quarries Association (RQA) 
SKAT Consult  
St Joseph Engineering Company (SJEC) Ltd 
Standards for Sustainability (SfS) 
Stonecraft Industries Ltd 
University of Rwanda - College of Science and Technology (UR - CST) 
Rwanda Standards Board (RSB) – Secretariat 
 DRS 540: 2023 
©RSB 2023- All rights reserved                  viii 
 Introduction 
The classification of the reaction to fire performance of construction products established by Delegated 
Regulation (EU) 2016/364 defines the reaction to fire classes for building products excluding floorings. The 
relevant test methods for determining the reaction to fire are being prepared by CEN/TC 127. 
Safety warning 
The attention of all persons concerned with managing and carrying out the tests described in this document is 
drawn to the fact that fire testing can be hazardous and that toxic and/or harmful smoke and gases can be 
produced during the test. 
An assessment of all potential hazards and risks to health should be made and safety precautions should be 
identified and provided. Smoke and gases should be removed from the workplace. Written safety instructions 
should be issued. Appropriate training should be given to relevant personnel. Laboratory personnel should 
ensure that they follow written safety instructions at all times. 
Special precautions are required for the propane gas supply system. 
 The equipment, for example tubes, couplings, flow meters, should be approved for propane. 
 The burner should be equipped with a remote-controlled ignition device, for example a pilot flame or a 
glow wire. There should be a warning system for leaking gas and a valve for immediate and automatic 
cut-off of the gas supply in case of extinction of the ignition flame. The pilot flames can be ignited directly 
by an operator in the test room; however, no one should be present in the test room during ignition of a 
burner. 
 It should be possible to operate the switch between auxiliary and main (primary) burner and the preceding 
main valve (to open or stop the propane supply) from outside the test room. 
Special precautions are required for the extinction of burning specimens. 
When the extinction is carried out because of intensive combustion of the specimens, it is recommended that 
a second operator is ready to intervene. Means for extinguishing should be available (e.g. since the heat 
output during intensive combustion can damage the apparatus). DRS 540: 2023 
1                ©RSB 2023- All rights reserved 
 Reaction to fire tests for building products — Building products 
excluding floorings exposed to the thermal attack by a single burning 
item 
2 Scope 
This Draft Rwanda standard specifies a method of test for determining the reaction to fire performance of 
construction products excluding floorings when exposed to thermal attack by a single burning item (SBI).The 
calculation procedures are given in Annex A. Information on the precision of the test method is given in Annex 
B. The calibration procedures are given in Annexes C and D, of which Annex C is a normative annex. 
NOTE This document has been developed to determine the reaction to fire performance of essentially flat products. The 
treatment of some families of products, e.g. linear products (pipes, ducts, cables etc.), can need special rules. 
3 Normative references 
The following documents are referred to in the text in such a way that some or all of their content constitutes 
requirements of this document. For dated references, only the edition cited applies. For undated references, 
the latest edition of the referenced document (including any amendments) applies. 
DRS 547 , Fire classification of construction products and building elements - Classification using data from 
reaction to fire tests 
ISO 13943:2017, Fire safety — Vocabulary 
4 Terms and definitions 
For the purposes of this standard, the terms and definitions given in ISO 13943 and the following apply.  
3.1 
backing board 
calcium silicate panel used to back the specimen that can be placed directly against a freestanding test 
specimen or at a distance from it 
3.2 
specimen 
piece of a product, which is to be tested 
Note 1 to entry: This can include the mounting technique used in its end-use application. This also can include 
an air gap and/or a substrate where appropriate. Comment [SN1]: Cant we change this and 
remove this part since it refer to the other 
standard  
Comment [SN2]: Was replaced by DRS 547  
©RSB 2023- All rights reserved                  2 
 3.3 
substrate 
product which is used immediately beneath the product about which information is required 
3.4 
THR600s 
total heat release from the specimen in the first 600 s of exposure to the main (primary) burner flames 
3.5 
LFS 
lateral flame spread on the long specimen wing 
Note 1 to entry: The LFS is defined in more detail in 8.3.3.  
3.6 
TSP600s 
total smoke production from the specimen in the first 600 s of exposure to the main (primary) burner flames 
3.7 
FIGRA0,2 MJ 
fire growth rate index 
maximum of the quotient of heat release rate from the specimen and the time of its occurrence using a THR-
threshold of 0,2 MJ 
Note 1 to entry: The FIGRA0,2 MJ is described in more detail in A.5.3.  
3.8 
FIGRA0,4 MJ 
fire growth rate index 
maximum of the quotient of heat release rate from the specimen and the time of its occurrence using a THR 
threshold of 0,4 MJ 
Note 1 to entry: The FIGRA0,4 MJ is described in more detail in A.5.3.  DRS 540: 2023 
3                ©RSB 2023- All rights reserved 
 3.9 
SMOGRA 
smoke growth rate index 
maximum of the quotient of smoke production rate from the specimen and the time of its occurrence  
Note 1 to entry: The SMOGRA is described in more detail in A.6.3.  
3.10 
sustained flaming 
persistence of flame on or over a surface for a minimum period of time 
[SOURCE: ISO 13943:2017] 
5 Test facility 
5.1 General 
The SBI test facility shall consist of a test room, the test apparatus (trolley, frame, burners, hood, collector and 
ducting), the smoke exhaust system and general measuring equipment. These components are specified in 
4.2 to 4.7. Design drawings are given in Annex G. Dimensions given in the drawings are nominal unless 
tolerances are given in the text. 
The air supply to the test room entering below the trolley should be fresh, uncontaminated air. 
5.2 Test room 
4.2.1 The test room shall have an inner height of (2,4 ± 0,05) m and an inner floor area of (3,0 ± 0,05) m in 
both directions. The walls shall be made of stone type building blocks (e.g. cellular concrete), gypsum boards, 
calcium silicate boards or other boards classified as class A1 or A2. 
4.2.2 One wall of the test room shall have an opening to insert the trolley from the surrounding laboratory into 
the test room. The opening shall be at least 1 470 mm wide and 2 450 mm high (dimensions of the frame). 
Windows shall be placed in the two walls facing the front side of the two perpendicular specimen planes. To 
be able to handle the SBI apparatus and the specimen when the trolley is in place, an additional door is 
needed. 
4.2.3 With the trolley in place in the test room, the distance between the long wing specimen surface touching 
the U-profile and the wall of the test room shall be (2,1 ± 0,05) m. This distance shall be measured 
perpendicularly to the wall facing the long wing. The areas of the openings in the test room, excluding the air 
inlet at the bottom of the trolley and the smoke exhaust opening in the hood, shall not exceed a total of 0,05 
m2.  
4.2.4 Both left-orientated arrangements, as shown in Figure 1, and right-orientated arrangements (the trolley 
shown in Figure 1 mirrored around a vertical line) are allowed. To be able to remove side plates of the hood  
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 without removing the collector, attention should be paid to the connection between the frame of the SBI 
apparatus and the ceiling of the room. It should be possible to move the side plate outwards at the bottom. 
NOTE The relative position of the frame in the test room depends on the details of the connection between room and 
frame. DRS 540: 2023 
5                ©RSB 2023- All rights reserved 
  
 
 
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 5.3 Materials 
Commercial propane , of minimum purity 95 %. 
5.4 Test apparatus 
NOTE See Figures E.1 to E.35.  
4.4.1Trolley,  on which two perpendicular specimen parts are placed, with a sandbox burner at the bottom of 
the vertical corner. 
The trolley is put in place with its back side closing the opening in the wall of the test room; the air inlet under 
the floor of the trolley is provided with perforated plates (open area to total area 40 % to 60 %; perforation 
diameter 8 mm to 12 mm) to produce an evenly distributed flow along the floor of the test room. 
Using a spirit level placed in the gully, periodically check the level of the L profile (behind the burner) and the 
C profile (in front of the specimen) to ensure they are horizontal. This will ensure that any material which melts 
and flows from the specimen will remain in the gulley during the test. 
In addition, periodically measure the level of the platform in front of the burner to ensure this is also horizontal. 
4.4.2Fixed frame,  in which the trolley is pushed and which supports the hood; a second burner is fixed to the 
frame. 
4.4.3Hood , on top of the frame, which collects the combustion gases. 
4.4.4Collector,  on top of the hood with baffles and a horizontal outlet for the exhaust duct. 
4.4.5Exhaust duct,  circular tube of inner diameter (315 ± 5) mm, and insulated with 50 mm high temperature 
resistant mineral wool, with the following parts (in flow direction): 
 connection to the collector; 
 ducting, of length 500 mm with four thermocouple mountings (for optional temperature measurements) at 
adistance of at least 400 mm from the collector (drawing E25 part A; optional); 
 ducting, of length 1 000 mm (drawing E25 part B; optional); 
 two 90° bends, (radius of curvature of axis 400 mm) (drawing E25 part C and D; optional); connection to 
the collector with an optional J-shaped bend; 
 ducting, of length 1 625 mm with guide vanes and an orifice; guide vane length 630 mm closest to the 
collector at a minimum distance of 50 mm; directly behind the guide vanes a (2,0 ± 0,5) mm thick circular 
orifice with inner opening diameter 265 mm and an outer diameter of 314 mm (drawing E25 part E; 
mandatory); DRS 540: 2023 
7                ©RSB 2023- All rights reserved 
  ducting, of length 2 155 mm with mountings for pressure-probe, four thermocouples, gassampling 
probeand white light extinction system; this section is called the “general measurement section” (drawing 
E25 part F; mandatory); 
 ducting, of length 500 mm (drawing E25 part G; mandatory); 
 connection to exhaust. 
Attention should be paid to the fixing of the measuring duct. The total mass excluding probes, etc. is about 
250kg. 
4.4.6 Two identical sandbox  burners (see Figure E.9), one in the bottom plate of the trolley (the “main 
(primary) burner”), one fixed to a post of the frame (the “auxiliary (secondary) burner”), with the following 
specifications: 
a) Shape: right angled triangle (top view) with two equal sides of 250 mm, height 80 mm, bottom closed 
except for a 12,5 mm pipe socket at the gravitational centre, top open. A rightangled triangular perforated 
plate shall be positioned in the burner at a height of 10 mm above the bottom. Metal gauze with a 
maximum mesh size of 2 mm shall be positioned at heights of 12 mm and 60 mm above the bottom. All 
dimensions shall be within ± 2 mm. 
b) Material: box made of 1,5 mm stainless steel, filled from bottom to top with, successively, a 10 mm void, a 
layer of pebbles within a size distribution of 4 mm to 8 mm up to a height of 60 mm, and a top layer of 
sand within a size distribution of 2 mm to 4 mm up to a height of 80 mm. The metal gauze is used to 
stabilize the two layers and prevent the pebbles from entering the gas pipe socket. The pebbles and sand 
used shall be rounded (river) stones, not broken ones. 
c) Position of main (primary) burner: mounted in the tray (see Figures E.9 and E.19) and connected to the U-
profile at the bottom of the specimen position. The top edge of the main (primary) burner shall be (25 ± 2) 
mm above the top edge of the U-profile. 
d) Position of auxiliary (secondary) burner: fixed to the post of the frame opposite to the specimen corner, 
with the top of the burner at a height of (1 450 ± 5) mm from the floor of the test room (1 000 mm vertical 
distance to the hood), its diagonal parallel and nearest to the hypotenuse of the main (primary) burner. 
e) The main (primary) burner is connected to U-profiles at the long and the short wing specimen position 
(see Figure E.18, part 10). In both U-profiles a blanking plate (see Figure E.19) is placed with its top at 
the same height as the top of the U-profile and at 0,3 m from the corner line between the mounted 
specimen wings (at the border of the burner zone, see 8.3.4). 
f) The main (primary) burner shall be protected with a tilted triangular grid when previous tests on the same 
type of product have led to an early termination to the test due to fallen material on the sand-bed in 
accordance with 8.5. The grid shall have a ratio of open area to total area of at least 90 %. One side of 
the grid shall be placed on the hypotenuse of the burner.  
The tilt angle is (45 ± 5)° with the horizontal, measured along the line from the hypotenuse midpoint to the 
specimen corner. See Figure E.36.   
©RSB 2023- All rights reserved                  8 
 4.4.7 Shield of rectangular shape , width (370 ± 5) mm, height (550 ± 5) mm, made of calcium silicate board 
(specification the same as the backing boards), to protect the specimens from the heat flux of the flames of 
the auxiliary (secondary) burner. 
It shall be fixed to the hypotenuse side of the auxiliary (secondary) burner, centred in the horizontal plane 
(shielding the total width of the diagonal plus (8 ± 3) mm at both sides) with the top edge (470 ± 5) mm above 
the top level of the auxiliary (secondary) burner. 
4.4.8 Mass flow controller  with a range of at least 0 g/s to 2,3 g/s and an accuracy of 1 % of the reading for 
the range 0,6 g/s to 2,3 g/s. The mass flow controller shall be calibrated annually. 
NOTE The propane flow of 2,3 g/s corresponds to a heat release of 107 kW using the effective lower heat of combustion 
of propane (46 360 kJ/kg). The accuracy of 1 % is when either using air, nitrogen or propane 
4.4.9 Switch , used to supply propane to either of the burners. 
The switch shall prevent propane being supplied to both burners at the same time, except during burner 
switching time (the short period of time in which the auxiliary (secondary) burner is decreasing and the main 
(primary) burner is increasing in output). This burner switch response time, calculated in accordance with 
C.2.1, shall be between 9 and 12 s. 
It shall be possible to operate the switch and the preceding main valve from outside the testing room. 
4.4.10 Backing boards , used to back the specimen wings in the trolley. 
The backing boards shall be high density calcium silicate boards as defined in Annex B  with a thickness of 
(12± 3) mm. The dimensions of the backing boards shall be: 
a) for the short wing: (at least 570 + thickness of the specimen) mm × (1 500 ± 5) mm; 
b) for the long wing: (1 000 ± 5) mm × (1 500 ± 5) mm. 
On the short wing, the backing board is wider than the specimen. The additional width shall extend at one side 
only. 
4.4.11 Removable panel parts,  to allow for additional airflow behind both specimen wings panels 22 and 25 
in Figure E.20 shall be replaced by half panels, covering only the upper half of the space covered by panels 
22 and 25. 
The panel shall only be removed under the conditions given in 5.2.2, a). 
5.5 Smoke exhaust system 
4.5.1 Under test conditions , the smoke exhaust shall be capable of continuously extracting a volume flow, 
normalized to 298 K, of 0,50 m3/s to 0,65 m3/s. 
4.5.2 The exhaust duct  shall have two side ducts (circular tubes of inner diameter 45 mm) horizontally 
perpendicular to and at the height of the longitudinal axis of the exhaust duct (see Figures E.32 and E.33). DRS 540: 2023 
9                ©RSB 2023- All rights reserved 
 4.5.3 The two possible configurations of the extraction duct are given in Figure E.1. The trolley opening in the 
test room is at the topside in the configuration drawings. The orientation of the duct may deviate from Figure 
E.1 if proof is provided that this does not change the airflow over the specimen. Removal of the 180° bend in 
the extraction duct and replacement of the hemispherical pressure probe are acceptable, provided that it is 
proved that the uncertainty in flow measurement is equal or better. 
NOTE Due to changes in heat output, some exhaust systems (especially those provided with local fans) can need manual 
or automatic readjustment during tests, to meet the requirement given in 4.5.1.  
The duct should be cleaned at intervals to avoid excessive accumulation of soot. 
5.6 General measurement section equipment 
NOTE See Figures E.28 to E.35.  
4.6.1 Three thermocouples,  all of the K-type in accordance with Annex C , diameter in the range 0,5 mm to 1 
mm, sheathed and insulated. 
The position of the tips shall be at a radius of (87 ± 5) mm from the axis and with 120° mutual angular 
distance. 
4.6.2 Hemispherical probe, connected to a pressure transducer with a range of at least 0 Pa to 100 Pa, and 
an accuracy of ± 2 Pa. (see reference [4]). 
The pressure transducer output shall have a 90 % response time of 1 s or better. 
4.6.3 Gas sampling probe, connected to a gas conditioning unit and gas analysers for O2 and CO2.  
a) The O2 analyser shall be of the paramagnetic type and capable of measuring at least a range of 16 % to 
21 % oxygen (VO2/Vair). The response time of the analyser shall be not more than 12 s (as measured in 
accordance with C.2.2). The noise and drift of the analyser shall be not more than 100 ppm over a period 
of 30 min (both as measured in accordance with C.1.3).  
The output from the analyser to the data acquisition system shall have a resolution of maximum 100 ppm. 
b) The CO2 analyser shall be of the IR type and capable of measuring at least a range of 0 % to 10 % 
carbon dioxide. The linearity of the analyser shall be 1 % of full scale or better. The response time of the 
analyser shall be not more than 12 s (as measured in accordance with C.2.2). The output from the 
analyser to the data acquisition system shall have a resolution of maximum 100 ppm. 
4.6.4 Light attenuation system, of the white light type, mounted with a flexible connection to the side ducts of 
the exhaust duct, and consisting of the following: 
a) Lamp, of the incandescent filament type and operating at a colour temperature of (2 900 ± 100) K. The 
lamp shall be supplied with stabilized direct current, stable within ± 0,5 % (including temperature, short-
term and long-term stability).  
©RSB 2023- All rights reserved                  10 
 b) Lens system, to align the light to a parallel beam with a diameter of at least 20 mm. The photocell 
aperture shall be placed at the focus of the lens in front of it and it shall have a diameter, d, chosen with 
regard to the focal length of the lens, f, so that d/f is less than 0,04. 
c) Detector, with a spectrally distributed responsivity agreeing with the CIE, V(γ)-function (the CIE photopic 
curves) to an accuracy of at least ± 5 %. The detector output shall, over an output range of at least two 
decades, be linear within 3 % of the measured transmission value or 1 % of the absolute transmission. 
For the calibration of the light attenuation system, see C.1.5. The 90 % response time of the system shall be 
not more than 3 s. 
To prevent smoke being trapped in the side ducts and the deposition of soot on the optics, air shall be 
introduced into the side ducts either by self-suction or pressurized airflow. If pressurized airflow is used, the 
flow rate shall be no more than 5 l/min. 
5.7 Other general equipment 
4.7.1 Thermocouple , ofthe K-type in accordance with Annex C, diameter (2 ± 1) mm, installed on the outer 
wall of the testing room within 0,20 m of the trolley opening and less than 0,20 m above the floor, for 
measuring the ambient temperature of the air flow into the test room. 
4.7.2Equipment for measuring the ambient pressure,  having an accuracy of ± 200 Pa (2 mbar). 
4.7.3 Equipment for measuring the relative ambient air humidity , having an accuracy of ± 5 % within the 
range 20 % to 80 %. 
4.7.4Data acquisition system  (used to record the data automatically) having an accuracy equal to or better 
than 100 ppm (0,01 %) for O2 and CO2, 0,5 °C for the temperature measurements, 0,01 % of full scale 
instrument output for all other instruments and 0,1 s for time. 
The data acquisition system shall record and store the following quantities every 3 s (information on a data file 
format is given in Annex F): 
a) time, in seconds; 
b) mass flow of propane gas through the burner, in milligrams per second; 
c) pressure difference from the hemispherical probe, in pascals; 
d) relative light intensity, dimensionless; 
e) O2 concentration, in (VO2/Vair) %; 
f) CO2 concentration, in (VCO2/Vair) %; 
g) ambient temperature at air inlet at bottom of trolley, in kelvins; 
h) three temperatures in general measurement section, in kelvins. DRS 540: 2023 
11                ©RSB 2023- All rights reserved 
  
6 Test specimen 
6.1 Dimensions of specimen 
5.1.1 The corner specimen consists of two wings , designated the short and long wings. The maximum 
thickness of a specimen is 200 mm. 
Sheet products shall have the following dimensions: 
a) short wing: (495 ± 5) mm × (1 500 ± 5) mm; 
b) long wing: (1 000 ± 5) mm × (1 500 ± 5) mm. 
NOTE If additional products are used to construct the specimen (in accordance with 5.3.2), the given dimensions refer to 
the total specimen dimensions. 
5.1.2 Specimens with a thickness of more than 200 mm shall be reduced to a thickness of 2000
-10 mm by 
cutting away the unexposed surface, unless otherwise specified in the product specification. 
5.1.3 Two horizontal lines shall be drawn on the front side of the long wing near the edge of the specimen 
farthest from the corner, to allow for observation of lateral flame spread reaching the edge between a height of 
(500 ± 3) mm and (1 000 ± 3) mm above the bottom edge of the specimen. Each line width shall be a 
maximum of 3 mm. 
6.2 Mounting of specimen 
6.2.1 Mounting as in end use application 
When products are tested, mounted as in their end use application, the test results are valid only for that 
application. 
6.2.2 Standard mounting 
When products are tested using a standard mounting, the test results are valid for that end use application 
and can be valid for a wider range of end use applications. The standard mounting used and its range of 
validity shall be in accordance with the relevant product specifications, and the following: 
a) Boards that are free standing in their end use application shall be tested free standing at a distance of 
at least 80 mm from the backing board. Boards that have in the end use application a ventilated cavity 
behind it shall be tested with a cavity of at least 40 mm width as well as with the smallest possible 
cavity width in the end-use application. For these two types of boards the sides of the cavity farthest 
away from the corner shall be open, the panels in accordance with 4.4.11 shall be removed and the 
cavities behind both specimen wings shall be in open connection. For other types of boards the sides 
of the cavity farthest away from the corner shall be closed, the panels in accordance with 4.4.11 shall 
be in place and the cavities behind both specimen wings shall not be in open connection.  
©RSB 2023- All rights reserved                  12 
 b) Boards that are fixed mechanically to a substrate in the end use application shall be tested fixed to a 
substrate using appropriate fixings. Fixings that stick out of the specimen surface shall be placed in 
such a way that the specimen wing can be placed against the U-profile at the bottom and against the 
other specimen wing at its side, over its full length. 
c) Boards that in their end use application are fixed mechanically to a substrate with a cavity behind it 
shall be tested with a cavity between substrate and backing board. The distance between the 
substrate and the backing board shall be at least 40 mm. 
d) Products that in their end use application are glued to a substrate shall be tested glued to a substrate. 
e) Products tested with a horizontal joint shall be tested with a horizontal joint in the long wing at a height 
of 500 mm from the bottom edge of the specimen. Products tested with a vertical joint shall be tested 
with a vertical joint in the long wing at a distance of 200 mm from the corner line, measured when the 
wings are mounted ready for testing. The centre line of the joint is decisive. 
NOTE 1 The bottom edge of the specimen is not visible when the specimen is installed in the trolley. The height 
is measured from the bottom edge of the specimen, not from the top of the U-profile of the trolley. 
f) Multi-layered products with air channels shall be tested with vertical channels. 
g) Standard substrates shall meet the requirements of Annex B . The dimensions of the substrates shall 
be in accordance with the dimensions of the specimens (see 5.1.1): 
1. for the short wing, the substrate shall be the length of the small wing plus the specimen and substrate 
thickness; 
2. the substrate for the long wing shall be identical to the lateral and vertical dimensions of the specimen 
g) Non-flat products shall be tested in such a way that not more than 30 % of a representative area of 250 
mm by 250 mm of the exposed surface area is more than 10 mm behind the vertical plane through the 
rear side of the U-profile. Non-flat products may be reshaped and/or may partly extend over the U-profile 
to the side of the burner to fulfil this requirement. A product shall not extend over the burner (i.e. 
maximum extension over the U-profile is 40 mm). 
h) If a product is not normally produced in a size large enough to provide one single test specimen for each 
specimen side, a special specimen shall be prepared as follows:  
Installation of full-size products should be started at the bottom of the corner joint between both wings. The 
specimen shall then be constructed from full size pieces of the product radiating outwards from this bottom 
corner so that the cut pieces are located at the edges of the specimen walls. 
Where the horizontal and/or vertical joint, in accordance with 5.2.2, e), is present in the test specimen, the 
positioning of the joints shall always prevail. The area of the parts of the long wing formed as a consequence 
of the horizontal and/or vertical joints shall be filled with full size products starting at the bottom corner, and 
again, with full size pieces, at the corner between the horizontal and vertical joints. 
Products are mounted for testing against the rear side of the U-profile (see 5.3.1). A mounted, totally flat 
product is therefore positioned in the vertical plane against the rear of the U-profile. Since the position of the DRS 540: 2023 
13                ©RSB 2023- All rights reserved 
 surface influences the heat received from the burner flames, the major parts of a non-flat product should not 
be far behind the vertical plane through the rear side of the U-profile. 
NOTE 2 Figure 2 is an example of an arrangement of the specimen and backing board. 
 
6.3 Installation of the specimen wings in the trolley 
6.3.1 The specimen wings shall be placed in the trolley as follows: 
a) The short wing specimen and backing board are placed on the trolley, with the extending part of the 
backing board at the main (primary) burner side and the bottom edge of the specimen against the short 
U-profile on the trolley floor. 
b) The long wing specimen and backing board are placed on the trolley, with the side edge of the backing 
board against the extending backing board of the short wing and the bottom edge of the specimen 
against the long U-profile on the trolley floor. 
 
©RSB 2023- All rights reserved                  14 
 c) Both wings shall be clamped at the top and the bottom. 
d) To ensure that the corner joint within the backing boards does not widen during the test, a metallic L-
profile, length 1 500 mm, shall be placed against the reverse side edge of the corner formed between the 
two wings. Connect the L-profile to the backing boards using fixings at a maximum of 250 mm centres. 
5.3.2 The exposed edges of the products and the joint in the corner may be protected using additional 
products, if this is in accordance with its end use application. When additional products are used, the width of 
the wings including the additional product shall be in accordance with 5.1.1.  
5.3.3 After installation of the specimen on the trolley, the following aspects shall be photographed:  
a) A total view of the exposed surface of the long wing. The centre point of the long wing shall be in the 
centre of the view. The camera shall be directed perpendicular to the surface of the long wing. 
b) A close-up of the vertical outer edge of the long wing at a height of 500 mm above the floor of the trolley. 
The camera angle shall be horizontal and at about 45° to the vertical plane of the wing. 
c) If additional products (in accordance with 5.3.2) are used a close-up of the edges and/or joints where the 
products are applied. 
6.4 Number of specimens 
At least three specimens (three sets of long plus short wing) shall be tested in accordance with Clause 8. 
If the product being tested has an orientational effect and this document or the product standard does not 
specify the orientation which has to be tested, the one specimen of the product shall be tested once in both 
directions. The test shall then be completed by test on the configuration with the worst classification 
parameters a further two times. This is only valid if one orientation has worse results for all classification 
parameters (FIGRA0,2 MJ, FIGRA0,4 MJ, THR600s, SMOGRA, TSP600s, LSF, burning droplets/particles). If 
some parameters are worse in one direction and others in the other direction, three specimen shall be tested 
in both directions. 
7 Conditioning 
6.1 The conditioning shall be in accordance with Annex B  and the requirements of 6.2.  
6.2 The parts that compose a specimen may be conditioned separately or fixed together. However, specimens 
that are tested glued to a substrate shall be glued before conditioning. 
NOTE Reaching constant mass can take longer for specimens that are fixed together. 
 
 
 DRS 540: 2023 
15                ©RSB 2023- All rights reserved 
  
8 Principle 
A test specimen, consisting of two vertical wings forming a right-angled corner, is exposed to the flames from 
a burner placed at the bottom of the corner (the “main (primary) burner”). The flames are obtained by 
combustion of propane gas, diffused through a sandbox and give a heat output of (30,7 ± 2,0) kW. 
The performance of the test specimen is evaluated over a period of 20 min. The performance parameters are: 
heat production, smoke production, lateral (horizontal) flame spread and falling flaming droplets and particles. 
A short period before ignition of the main (primary) burner is used to measure the heat output and smoke 
development of the burner only, using an identical burner away from the specimen (the “auxiliary (secondary) 
burner”). 
Some measurements are performed automatically, some are made by visual observation. The exhaust duct is 
equipped with sensors to measure the temperature, light attenuation, O2 and CO2mole fraction and a flow 
induced pressure difference in the duct. These quantities are recorded automatically and used to calculate the 
volume flow, the heat release rate (HRR) and the smoke production rate (SPR). 
Visual observations are made of the horizontal flame spread and falling of flaming droplets and particles. 
9 Test procedure 
9.1 General 
Perform the steps in 8.2 in sequence, with the measuring equipment operating and the trolley with the test 
specimen and the main (primary) burner placed in the frame, under the hood. The entire testing procedure 
until the end of the test shall be carried out within 2 h of removal of the specimen from the conditioning 
environment. 
All electronic devices and pumps shall be switched on sufficiently long beforehand to reach equilibrium before 
conducting any calibration or testing. 
Half an hour has been found suitable for most devices. The stabilization time of gas-analysers however is 
much longer. It is recommended that the gas-analysers remain on all the time. 
9.2 Testing operations 
Set the volume flow of the exhaust, V298(t), to (0,60 ± 0,05) m3/s [(calculated in accordance with A.5.1.1, a))]. 
This volume flow shall be within the range 0,50 m3/s to 0,65 m3/s during the total test period. 
NOTE Due to changes in heat output, some exhaust systems (especially those provided with local fans) can need manual 
or automatic readjustment during the test, to meet the requirement given. 
8.2.2 Record the temperatures T1, T2 and T3 of the thermocouples in the exhaust duct and the ambient 
temperature for at least 300 s. The ambient temperature shall be within (20 ± 10) °C, and the temperatures in 
the duct shall not differ more than 6 °C from the ambient temperature.  
©RSB 2023- All rights reserved                  16 
 8.2.3 Ignite the pilot flames of both burners (if pilot flames are used). Changes in the gas supply to the pilot 
flames during the tests shall not exceed 5 mg/s. 
8.2.4 Record the pre-test conditions. The data to be recorded are given in 8.3.2.  
8.2.5 Start the time measurement with the chronometer and the automatic recording of data. The time of start 
is t = 0 s. The data to be recorded are given in 8.4.  
8.2.6 At t = (120 ± 5) s: Ignite the auxiliary (secondary) burner and adjust the propane mass flow m gas to (647 
± 10) mg/s. The adjustments shall be made before t = 150 s. The mass flow shall be within this range during 
the total test period. 
NOTE The time period 210 s < t < 270 s is used to measure the base line for the heat release rate.8.2.7 At t = (300 ± 5) s: 
Switch the propane supply from the auxiliary (secondary) burner to the main (primary) burner. 
8.2.8 Observe the burning behaviour of the specimen for a period of 1 260 s and record the data on the record 
sheet. The data to be recorded are given in 8.3.3 and 8.3.4.  
NOTE The nominal exposure period of the specimen to the flames of the main (primary) burner is 1 260 s. The 
performance is evaluated over a period of 1 200 s.8.2.9 At t ≥ 1 560 s: 
a) terminate the gas supply to the burner; 
b) stop the automatic recording of data. 
8.2.10 Record the end of test conditions on the record sheet at least 1 min after any remaining combustion of 
the specimen has been totally extinguished. The data to be recorded are given in 8.3.5.  
The end of test conditions should be recorded without the influence of remaining combustion. If the specimen 
is difficult to extinguish totally, the trolley can be removed. 
9.3 Visual observation and manual recording of data 
9.3.1 General 
The quantities mentioned in this clause shall be observed visually and recorded in the format given. The 
observer shall be provided with a chronometer equipped with an event logger. The observations shall be 
recorded on a record sheet, of which an example is given in Annex G.  
9.3.2 Pre-test conditions 
The following quantities shall be recorded: 
a) ambient pressure (Pa); 
b) ambient relative humidity (%H2O); DRS 540: 2023 
17                ©RSB 2023- All rights reserved 
 c) ambient temperature (°C). 
 
9.3.3 Lateral flame spread on the long wing 
The lateral (horizontal) flame spread shall be recorded as the occurrence of sustained flames reaching the far 
edge of the long wing specimen at any height between 500 mm and 1 000 mm at any time during the test. The 
determining phenomenon shall be the boundary of sustained flaming for a minimum period of 5 s at the 
surface of the specimen. 
If the lateral flame spread criteria is not met, additional tests may be conducted, at request of the sponsor, 
with the large wing having a width of 1 m plus the thickness of the specimen. 
If in three additional tests the flame does not reach the edge of the long wing, the LFS criterion shall be 
considered to be met. 
9.3.4 Flaming particles or droplets 
If flaming particles or droplets are expected, the test shall be recorded continuously using a suitable high-
resolution camera. 
The fall of flaming droplets or particles shall be recorded only within the first 600 s of the exposure period and 
only when the droplets/particles reach the floor level of the trolley (the level of the lower edge of the specimen) 
outside the burner zone. The burner zone is defined as the trolley floor area at the front side of the specimen 
wings, less than 0,3 m from the corner line between the specimen wings, as illustrated in Figure 3. The 
following occurrences shall be recorded:  
a) the fall of a flaming droplet/particle, in the given time interval and area, that remains flaming for not more 
than 10 s after falling; 
b) the fall of a flaming droplet/particle, in the given time interval and area, that remains flaming for more than 
10 s after falling. 
A quarter circle drawn on the floor of the trolley is needed to mark the boundary of the burner zone. The line 
width shall be less than 3 mm. 
Flaming parts of the specimen touching the floor of the trolley outside the burner zone should be regarded as 
fallen particles although the part concerned can still be an integral part of the specimen (e.g. bending of a 
weakened product). 
NOTE To prevent molten material from flowing from inside to outside the burner zone, an obstruction plate is placed in 
both long and short wing U-profiles on the border of the burner zone (see 4.4.6). 
 
  
©RSB 2023- All rights reserved                  18 
  
 
 
 
9.3.5 End of test conditions 
The following quantities shall be recorded: 
a) light transmission at the “general measuring section” in the exhaust duct (%); 
b) O2 mole fraction at the “general measuring section” in the exhaust duct; 
c) CO2 mole fraction at the “general measuring section” in the exhaust duct. 
DRS 540: 2023 
19                ©RSB 2023- All rights reserved 
 9.3.6 Recorded events 
The following events shall be recorded: 
a) occurrence of a surface flash; 
b) smoke from the specimen not entering the hood during the test, but flowing out of the trolley into the 
surrounding testing room; 
c) falling of parts of the specimen; 
d) development of a gap in the corner (failure of mutual fixing of backing boards); 
e) occurrence of one or more of the conditions which justify an early termination of the test in accordance 
with8.5;  
f) occurrence of distortion or collapse of the specimen; 
g) all additional events that may be of importance to the correct interpretation of the test results or to the field 
of application of the product. 
9.4 Automated recording of data 
8.4.1 The quantities given in 8.4.2 to 8.4.9 shall be measured and recorded automatically every 3 s during the 
period specified in 8.2 and shall be stored for further processing. 
8.4.2 Time (t), in seconds; at the start of recording of data, t = 0 by definition. 
8.4.3 Mass flow rate of propane gas to the burner (mgas) in milligrams per second. 
8.4.4 Pressure difference over the hemispherical probe (Δp), at the general measuring section in the exhaust 
duct, in pascals. 
8.4.5 Signal from the light receiver (I), of the white light system at the general measuring section in the 
exhaust duct, in percent. 
8.4.6 O2 mole fraction in exhaust flow (xO2), sampled at the gas sampling probe in the general measuring 
section in the exhaust duct. 
8.4.7 CO2 mole fraction in exhaust flow (xCO2), sampled at the gas sampling probe in the general measuring 
section in the exhaust duct. 
The oxygen and carbon dioxide concentrations are measured only in the exhaust duct; both concentrations 
are assumed to be constant in the air that enters the test room. It should be noted that the air supplied from a 
space where oxygen is consumed (e.g. by fire tests) cannot fulfil this assumption. Also applies for 8.4.6.  
©RSB 2023- All rights reserved                  20 
 8.4.8 Ambient temperature (T0) at the air inlet at the bottom of the trolley, in kelvins. 
8.4.9 The three temperatures (T1, T2 and T3) in the general measuring section in the exhaust duct, in kelvins. 
9.5 Early termination of test 
The main (primary) burner shall be stopped earlier than the nominal exposure period if the material falls onto 
the sand-bed of the burner that substantially disturbs the flame of the burner or extinguishes the burner by 
choking. 
Note that consideration should be given to the early termination of the test if half the burner is blocked by fallen material. 
Record the time of termination of the gas supply to the burner and the reason why. 
The results of a test are not valid for classification purposes when an early termination of the test has 
occurred. 
NOTE An early termination of the test can be prevented by the use of a grid in accordance with 4.4.6.  
The following occurrences may damage the test apparatus: 
a) a heat release rate of the specimen exceeding 350 kW at any instant, or exceeding 280 kW over a period 
of 30 s; or 
b) an exhaust duct temperature exceeding 400 °C at any instant, or exceeding a mean value of 300 °C over 
a period of 30 s. 
If the above limits are exceeded the operator may consider an early termination of the test. Measured values 
for the temperature and the heat release rate will contain a certain amount of noise. It is therefore advised not 
to stop the test on the basis of only one or two successive measurement values from the instruments 
exceeding the given maximums. 
10 Expression of results 
9.1 For each test, the burning behaviour of the product shall be represented by graphs of average heat 
release rate HRRav(t), total heat release THR(t), and 1 000 × HRRav(t)/(t - 300), for the time interval 0 ≤ t ≤ 1 
500 s; the values for the fire growth rate indices FIGRA0,2 MJ and  
FIGRA0,4 MJ, and the total heat release within 600 s THR600s, calculated in accordance with A.5, and the 
occurrence or not of lateral flame spread up to the edge of the specimen in accordance with 8.3.3.  
9.2 For each test, the smoke production behaviour of the product shall be given as the graphs of SPRav(t), 
total smoke production TSP(t) and 10 000 × SPRav(t)/(t - 300), for the time interval 0 ≤ t ≤ 1 500 s; and the 
values for the smoke growth rate index SMOGRA and the total smoke production within 600 s TSP600s, 
calculated in accordance with A.6.  DRS 540: 2023 
21                ©RSB 2023- All rights reserved 
 9.3 For each test, the behaviour of the product regarding the production of flaming droplets and particles shall 
be given as the occurrence, or not, of one or both categories of fallen flaming droplets and particles, in 
accordance with 8.3.4, a) or b) respectively. 
 
 
11 Test report 
The test report shall include the following information. A clear distinction shall be made between the data 
provided by the sponsor and data determined by the test: 
a) a reference that the test was carried out in accordance with this document; 
b) any deviations from the test method; 
c) name and address of the testing laboratory; 
d) date and identification number of the report; 
e) name and address of the sponsor; 
f) name and address of the manufacturer/supplier, if known; 
g) date of sample arrival; 
h) identification of the product; 
i) description of the sampling procedure, where relevant; 
j) a general description of the product tested including the density, mass per unit area andthickness, 
together with the form of construction of the test specimen; 
k) description of substrate and fixing to the substrate (if used); 
l) details of conditioning; 
m) date of test; 
n) test results expressed in accordance with Clause 9 including method of smoke calculation (A.6.1.2); 
o) photographs in accordance with 5.3.3;  
p) observations made during the test;  
©RSB 2023- All rights reserved                  22 
 q) the following statement: “The test results relate to the behaviour of the test specimens of a product under 
the particular conditions of the test; they are not intended to be the sole criterion for assessing the 
potential fire hazard of the product in use”. 
 
 
 DRS 540: 2023 
23                ©RSB 2023- All rights reserved 
 Annex A 
(normative)  
 
Calculation precedures 
A.1 General 
A.1.1 General remarks 
A.1.1.1 General 
The test procedure is described in Clause 8. Some information is repeated here for convenience. 
a) Major events during this procedure are: 
1. t = 0 s : start data acquisition; 
2. t = (120 ± 5) s : start auxiliary (secondary) burner; 
3. t = (300 ± 5) s : switch from auxiliary to main (primary) burner; 
4. t ≥ 1 560 s : stop main (primary) burner and stop data acquisition. 
b) The performance of the specimen is evaluated during the first 1 200 s (300 s ≤ t ≤ 1 500 s) in which the 
specimen is exposed to the flames of the main (primary) burner. This period is called the exposure 
period. 
c) Due to the use of time-averaged quantities, accepted inaccuracies and delay times, a maximum of 60 s 
additional data under burner flame exposed conditions (after t = 1 500 s) is needed. 
d) The time interval 210 s ≤ t ≤ 270 s is used to do measurements on the burner heat output only. This 
interval is called the base line period. After t = 300 s the average burner heat output during the base line 
period is subtracted from the total heat output of burner and specimen, to get the output of the specimen 
only. 
The average burner smoke base line output is determined from the test described in Clause A.6.1.2. In a 
product test, after t = 300 s the average burner smoke base line output (as determined in A.6.1.2) is 
subtracted from the total smoke output of burner and specimen, to get the output of the specimen only. 
e) The following “raw” data are recorded every 3 s for 1 560 s: gas flow, pressure difference, light 
attenuation, oxygen and carbon dioxide concentration and the ambient and smoke temperatures, all in 
accordance with 8.4.  
  
©RSB 2023- All rights reserved                  24 
 A.1.1.2 Notation 
In this annex, a simplified notation is used for averages over a time period: 
f(t1...t2) is defined as the average value of f(t), in the time period t1≤ t ≤ t2 
A.1.2 Calculations to be performed on the test data 
After a test, a series of parameters shall be calculated to evaluate the performance of the product. All 
calculations in this annex, excluding the calculations in A.2, shall be performed on data shifted in time in 
accordance with A.2. The following calculations shall be carried out: — synchronization of data;  
 calculation of equipment response;  
 calculation of exposure period;  
 calculation of HRR(t);  
 calculation of time-averaged HRR(t): HRR30s(t);  
 calculation of THR(t) and THR600s;  
 calculation of FIGRA 0,2MJ and FIGRA 0,4MJ;  
 calculation of SPR(t);  
 calculation of time-averaged SPR(t): SPR60s(t);  
 calculation of TSP(t) and TSP600s;  
 calculation of SMOGRA.  
The results of a test are valid only when the requirements of A.2 and A.3 have been met. The calculations are 
specified in A.2 to A.6.  
A.1.3 Calculations to be performed on calibration data 
The calibration procedures are specified in Annex C. The quantities to be calculated are specified in A.7 if not 
already specified in A.2 to A.6 as part of the analysis of standard test data. 
A.1.4 Standard data set 
As the calculation methods are complex a standard data set can be used to verify the calculation steps and 
benchmark software. DRS 540: 2023 
25                ©RSB 2023- All rights reserved 
 A.2 Synchronization of data 
A.2.1 A 
A.2.2 O2 and CO2 synchronization with Tms. 
Due to the switch from auxiliary to main (primary) burner, the major quantities measured show a short peak or 
dip at the same moment in time. These peaks and dips are used to synchronize the data. It is assumed that 
this automatic synchronization procedure and/or the measured delay times are erroneous if the shift 
calculated by this automatic synchronization procedure differs by more than 6 s from the delay times of the 
analysers determined in the calibration procedure according to C.2.2. 
a) Shift the O2 and CO2 data for the delay times found during calibration in accordance with C.2.2. 
 
b) The time t 0_T is calculated as the time of the last data point before the temperature in the general 
measurement section Tms(t) drops by more than 2,5 K, after t = 270 s, relative to the average of Tms 
during the base line period (210 s ≤ t ≤ 270 s): 
 
Where: 
Tms(t) is the temperature in the general measurement section calculated according to A.3.2. 
c) The time t0_O2 is calculated as the time of the last data point before the oxygen concentration rises by 
more than 0,05 % (500 ppm), after t = 270 s, relative to the average during the base line period (210 s ≤ t 
≤ 270 s): 
 
 
Where: 
xO2 is the oxygen concentration in mole fraction. 
 
d) The time t 0_CO2 is calculated as the time of the last data point before the carbon dioxide concentration 
xCO2 drops more than 0,02 % (200 ppm), after t = 270 s, relative to the average during the base line 
period (210 s ≤ t ≤ 270 s): 
 
 
 
©RSB 2023- All rights reserved                  26 
 e) The oxygen and carbon dioxide data are shifted so that the O2 peak and the CO2 dip coincides with the 
dip in Tms (such that t0_T = t0_O2 = t0_CO2). Both shifts shall not be more than 6 s. 
 
The same equation is valid for CO 2 after replacement of O 2 by CO 2 in the formula. 
NOTE In some cases, the peaks and dips used for synchronisation can be too small to be found with the procedure 
presented here. In those cases, a visual assessment of t0_T, t 0_O2 and/or t 0_CO2 is acceptable. 
A.2.2 Shift all data to t = 300 s.  
After the O 2 and CO 2 synchronization with Tms, the time is shifted for all data such that  
t0 = t0_T = t0_O2 = t0_CO2 = 300 s for convenience. This shift shall be less than 15 s.  
NOTE Here all data ( mgas, Δp, I, xO2, xCO2, T0, T1, T2, T3 and Tms) are shifted in time together. In A.2.1, e), the 
O2 and CO 2 data were shifted in time relative to the other data.  
A.2.3 All calculations in A.3 to A.6 shall be performed on data shifted in time in accordance with this clause.  
A.3 Checking equipment response 
A.3.1 Temperature readings 
The temperature readings of thermocouples 1, 2 and 3, all mounted in the general measurement section, shall 
differ by not more than 1 % of the average value.  
Tms [ = (T1 + T2 + T3)/3] at any time in more than ten data points with the exception of the following.  
If one thermocouple differs by more than 1 % from Tms in more than ten data points and the two remaining 
thermocouples do not differ more than 1 % from their average in more than ten data points, that thermocouple 
shall be fully excluded from the calculation of Tms in this test. In other cases all thermocouples shall be used to 
calculate Tms. The use of only two thermocouples shall be mentioned in the test report.  
NOTE 1 This requirement is given to exclude thermocouples that malfunction. A deviation by more than 1 % in only a few 
data points is not assumed to be the result of a malfunction.  
NOTE 2  For the start of tests or calibrations, additional criteria for temperatures are given.  
DRS 540: 2023 
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 A.3.2 Drift in gas concentration measurement 
The drift in both xO2 and xCO2 gas concentration measurements is calculated as the difference between the 
start values calculated as xO2(30 s...90 s) and xCO2(30 s...90 s) respectively, and the end values obtained by 
visual recording after a period of at least 60 s, in which no combustion products enter the exhaust duct.  
Criteria:  
| xO2_begin - xO2_end| ≤ 0,02%  (A.5) 
| xCO2_begin - xCO2_end | ≤ 0,02 %   (A.6) 
where  
xO2 is the oxygen concentration in mole fraction;  
xCO2  is the carbon dioxide concentration in mole fraction.  
A.3.3 Drift in light attenuation measurement 
The drift in the light attenuation measurement I is calculated as the difference between the start value, 
calculated as I (30 s…90s) and the end value, obtained by visual recording after a period of at least 60 s in 
which no combustion products enter the exhaust duct. 
 
A.4 Exposure period 
The specimens are exposed to the flames of the main (primary) burner from t = t0 = 300 s, until the propane 
supply to the burner is stopped ( t´). The exposure period is equal to t´ – t0.  
Check that the burner has stopped by noting the first moment t´ after t0 at which the propane mass flow is 
lower than 300 mg/s at t´ as well as at the next data point ( t´+3 s): 
 
 
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A.5 Heat output 
A.5.1 Calculation of heat release rate (HRR) 
A.5.1.1 Total HRR of specimen and burner: HRRtotal 
a) Calculation of the volume flow of exhaust system, normalized at 298 K, V298(t): 
 
b) Calculation of the oxygen depletion factor: 
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c) Calculation of xa_O2: 
 
d) Calculation of HRRtotal(t): 
 
 
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 A.5.1.2 HRR of the burner 
The HRRburner(t) is equal to HRRtotal(t) during the base line period. The average HRR of the burner is 
calculated as the average HRRtotal(t) during the base line period (210 s ≤ t ≤ 270 s): 
 
The level and stability of the burner during this base line period shall meet the following criteria.  
Criteria: 
 
The ratio of carbon dioxide production to oxygen depletion during the base line period (210 s ≤ t ≤ 270 s; 
combustion of propane only) can be used as a check of the gas analysers before the burner switch operates. 
The ratio should be equal to 0,60 ± 0,05. 
 
 
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 A.5.1.3 HRR of the specimen 
In general, the heat release rate of the specimen is taken as the total heat release rate HRRtotal(t) minus the 
average heat release rate of the burner HRR av_burner: 
 
During the switch from the auxiliary to the main (primary) burner at the start of the exposure period, the total 
heat output of the two burners is less than HRR av_burner. Formula (A.17) then gives negative values for HRR(t) 
for at most 12 s (burner switch response time). Such negative values and the value for t = 0 are set to zero, as 
follows: 
 
A.5.1.4 Calculation of HRR30s 
 
 
 
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 A.5.2 Calculation of THR(t) and THR600s 
The total heat release of the specimen THR(t) and the total heat release of the specimen in the first 600 s of 
the exposure period (300 s ≤ t ≤ 900 s), THR600s, are calculated as follows: 
 
A.5.3 Calculation of FIGRA0,2MJ and FIGRA0,4MJ (fire growth rate indices) 
The FIGRA indices are defined as the maximum of the quotient HRRav(t)/(t - 300), multiplied by 1 000. The 
quotient is calculated only for that part of the exposure period in which the threshold levels for HRRav and 
THR have been exceeded. If one or both threshold values of a FIGRA index are not exceeded during the 
exposure period, that FIGRA index is equal to zero. Two different THR-threshold values are used, resulting in 
FIGRA0,2MJ and FIGRA0,4MJ.  
a) The average of HRR, HRRav, used to calculate the FIGRA is equal to HRR30s according to A.5.1.4, 
with the exception of the first 12 s of the exposure period. For data points in the first 12 s, the average 
is taken only over the widest possible symmetrical range of data points within the exposure period: 
 
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 b) Calculate FIGRA 0,2MJ for all t where: 
(HRRav(t) > 3 kW) and (THR(t) > 0,2 MJ) and (300 s < t ≤ 1 500 s); 
and calculate FIGRA 0,4MJ for all t where: 
(HRR av(t) > 3 kW) and (THR(t) > 0,4 MJ) and (300 s < t ≤ 1 500 s); 
both using: 
 
Where: 
FIGRA  is the fire growth rate index, in watts per second;  
HRRav(t)  is the average of HRR(t) as specified in a), in kilowatts;  
max. [a(t)]  is the maximum of a( t) within the given time period.  
NOTE As a consequence, specimens with an HRRav value of not more than 3 kW during the total test period or a THR 
value of not more than 0,2 MJ over the total test period, have a FIGRA 0,2MJ equal to zero. Specimens with an HRRav value of 
not more than 3 kW during the total test period or a THR value of not more than 0,4 MJ over the total test period, have a 
FIGRA 0,4MJ equal to zero. 
 
 
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 A.6 Smoke production 
A.6.1 Calculation of smoke production rate (SPR) 
A.6.1.1 Total SPR of specimen and burner: SPRtotal 
 
 
For calculation purposes, set I(t) = MAX[10e-9, I(t)]) to avoid possible division by zero errors.  
 
 
 
 
 
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 A.6.1.2 SPR of the burner  
It has been observed that the auxiliary (secondary) burner produces less smoke than the main (primary) 
burner. In order to ensure that the burner output is not a contributing part of the product's smoke 
classification, the contribution of the burner is derived from the burner itself. The procedure – which is 
mandatory – is as follows and results are only valid for tests run on the same testing day:  
a) Place clean sheets of calcium silicate “substrate” directly into the trolley to form a corner.  
b) Position the trolley in the test room and commence a normal test running the burners and software as 
normal.  
c) The test may be terminated at any time after 600 s.  
The average SPR of the burner is calculated as the average SPRtotal(t) during the period (390 s ≤t≤ 450 s):  
 SPRav_burner = SPRtotal (390 s…450 s)  (A.27)  
where  
SPRtotal(t)  is the total smoke production rate of specimen and burner, in square metres per second;  
SPRav_burner is the average smoke production rate of the burner, in square metres per second.  
The standard deviation of SPR burner(t), σbs, during the period 390 s ≤t≤ 450 s is calculated as follows, using the 
“non-biased” or “n - 1” method: 
 
where  
SPRav_burner is the average smoke production rate of the burner, in square metres per second;  
SPRburner(t)  is the smoke production rate of the burner, in square metres per second; n  is the 
number of data points ( n = 21).  
The level and stability of the burner during this base line period shall meet the following criteria.  
Criteria:  
SPRav_burner = (0 ± 0,2) m2/s  
and  (A.29) 
 
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 σbs< 0,01 m2/s  (A.30) 
where  
SPRav_burner is the average smoke production rate of the burner, in square metres per second;  
 σbs is the standard deviation of RSPburner(t), during the period 390 s ≤t≤ 450 s.  
A.6.1.3 SPR of the specimen  
In general, the SPR of the specimen is taken as the total smoke production rate SPRtotal(t), minus the average 
SPR of the burner, SPRav_burner.  
SPR( )t = SPRtotal ( )t −SPRav_burner (A.31)  
where  
SPRtotal(t)  is the total smoke production rate of specimen and burner, in square metres per 
second;  
SPRav_burner is the average smoke production rate of the burner, in square metres per second;  
 SPR(t)  is the smoke production rate of the specimen, in square metres per second.  
During the switch from auxiliary (secondary) to main (primary) burner at the start of the exposure period, the 
total smoke production of the two burners might be less than SPRav_burner. Formula (A.31) may then lead to 
negative values for SPR(t) for a few seconds. Such negative values, and the value for t = 0, are set to zero:  
For t = 300 s:  
SPR(300) = 0 m2/s  
For 300 s < t≤ 312 s:  
 SPR( )t = max.[ ,(0 SPRtotal ( )t −SPRav_burner )] (A.32)  
where   
SPRtotal(t)  is the total smoke production rate of specimen and burner, in square metres 
per second;  
SPRav_burner is the average smoke production rate of the burner, in square metres per 
second;  DRS 540: 2023 
37                ©RSB 2023- All rights reserved 
 SPR(t)  is the smoke production rate of the specimen, in square metres per second;  
max. [a,b]  is the maximum of two values a and b. 
NOTE The smoke production of the burner flames most probably changes when the specimen starts to produce 
combustible volatiles. However, the base line smoke production is taken as a first approximation with acceptable 
accuracy, especially at the start of the exposure period where the base line level is important for the SMOGRA calculation.  
A.6.1.4 Calculation of SPR60s 
SPR60s(t) is the 60 s average of SPR(t).  
 
A.6.2 Calculation of TSP(t) and TSP600s 
The total smoke production of the specimen TSP(t) and the total smoke production of the specimen in the first 
600 s of the exposure period (300 s ≤ t ≤ 900 s), TSP600s, are calculated as follows: 
 
NOTE The factor 3 is introduced since only one data point is available every three seconds. 
 
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A.6.3 Calculation of SMOGRA (smoke growth rate index) 
The SMOGRA is defined as the maximum of the quotient SPRav(t)/(t - 300), multiplied by 10 000.  
The quotient is calculated only for that part of the exposure period in which the threshold levels for SPRav and 
TSP have been exceeded. If one or both threshold values are not exceeded during the exposure period, 
SMOGRA is equal to zero. 
a) The SPRav, used to calculate the SMOGRA is equal to SPR60s according to A.6.1.4 with the exception of 
the first 27 s of the exposure period. For data points in the first 27 s, the average is taken only over the widest 
possible symmetrical range of data points within the exposure period: 
 
Where: 
SMOGRA  is the smoke growth rate index, in square metres per square second;  
SPRav(t)  is the average of SPR(t) as specified in a), in square metres per second;  
max.[a(t)]  is the maximum of a(t) within the given time period.  
NOTE 1 As a consequence, specimens with a SPRav value of not more than 0,1 m2/s during the total test period or a TSP 
value of not more than 6 m2 over the total test period have a SMOGRA value equal to zero.  
NOTE 2 A SMOGRA value given in the units m2/s2 does not have a direct physical meaning because its calculation 
contains a multiplication factor of 10 000. 
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11.1.1 A.7Calculations for calibrations – Propane heat release  
A.7.1 The theoretical heat release rate of the propane mass flow is calculated as:  
 
where qgas(t)  is the theoretical heat release rate of the propane mass flow, in kilowatts;  
Δhc,eff is the effective lower heat of combustion of propane = 46 360 kJ/kg;  
mgas(t)  is the propane mass flow rate, in kilograms per second. A.7.2 The 30 s average of qgas(t), is 
calculated as:  
 
where  
qgas, 30 s(t)  is the average of qgas(t) over 30 s, in kilowatts;  
qgas(t)  is the theoretical heat release rate of the propane mass flow, in kilowatts.  
 
 
 
 
 
 
 
 
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  DRS 540: 2023 
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 Annex B 
(normative)  
 
Conditioning procedures and general rules for selection of substrates 
B.1 Conditioning procedures 
B.1.1 General 
Test specimens used by the laboratory to conduct tests according to ISO 1182, ISO 1716, ISO 9239-1, 
andISO 11925-2shall be conditioned at a temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) %.  
NOTE This corresponds to the recommended atmosphere and normal tolerances given in ISO 554.  
Test specimens shall be arranged within the conditioning environment in such a way that air can 
circulatearound each individual test specimen.  
Test specimens shall be conditioned either until constant mass is achieved (see B.1.2) or for a fixed period 
(see B.1.3). 
B.1.2 Conditioning to constant mass 
Before testing, the test specimens shall be conditioned in the atmosphere specified in 4.1 for a minimum 
period of 48 h, until constant mass is achieved.  
Constant mass is considered to be achieved when two successive weighing operations, carried out at 
aninterval of 24 h, do not differ by more than 0.1 % of the mass of the specimen or 0.1 g, whichever is the 
greater. A number of weighing devices may be necessary. At least one weighing device shall have an 
accuracy of at least 0.1 g. 
B.1.3 Conditioning for a fixed period 
Before starting conditioning for a fixed period, the test specimens shall be properly cured in accordancewith 
manufacturer's instructions and shall not contain excess water. The content of excess water shall be 
measured and shall be below 40 % before the test specimens are placed in the conditioning environment. 
Before testing the test specimens shall be conditioned in the atmosphere specified in 4.1 for the following 
minimum periods: 
a) Minimum conditioning period of eight weeks:  
1. fire retardant treated wood and fire-retardant treated wood-based products;  
2. cement based products;  
b) Minimum conditioning period of four weeks:  
1. not fire-retardant treated wood and not fire-retardant treated wood-based products;   
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 2. calcium silicate products;  
3. gypsum and gypsum-based products;  
4. all other products containing hygroscopic materials;  
c) Minimum conditioning period of two weeks: all other products. 
B.2 General rules for selection of substrates 
B.2.1 General 
The substrates used by the laboratory to conduct tests according to ISO 9239-1 and ISO 11925-2shall 
be evaluated when appropriate to determine their reaction to fire test performance and thus 
compliance with this standard. One indicative test shall be conducted on each batch of substrates.  
B.2.2 Standard substrates for floorings 
5.2.1 Test results using a standard substrate complying with the requirements of 5.2.2 or 5.2.3 are applicable 
if the density of the end use substrate is at least 75 % of the nominal value of the density of that standard 
substrate.  
5.2.2 End use substrates of classes A1 and A2-s1,d0 are represented by fibre cement board (in accordance 
with ISO 390) with thickness (8 ± 2) mm, with density (1 800 ± 200) kg/m3 and with classification A2fl-s1, 
when – insofar as for the ISO 9239-1 test – the fibre cement board is tested as flooring but without a 
substrate.  
5.2.3 End use substrates of wood and of classes A1 and A2-s1,d0 are represented by not fire retardant 
treated particleboard with thickness (20 ± 2) mm, with density (680 ± 50) kg/m3and with classification Cfl-s1 
when tested (according to ISO 9239-1) as flooring but without a substrate.  
5.2.4 When the end use substrates are not of wood and not of class A1 and not of class A2-s1,d0, the flooring 
shall be tested in end use condition.  
5.2.5 The method of attachment (e.g. adhesive) of floorings shall be representative of end use application. 
The method of attachment in end use practice shall be reproduced in the preparation of the test specimens, 
i.e. end use adhesive and end use quantities, etc. If the order in which the attachments are conducted is 
known, this shall also be reproduced in the test specimens, e.g. if in end use practice the adhesive is applied 
to the substrate and not to the flooring, then it shall be applied to the substrate during the test specimen 
preparation. The same or greater time for curing and drying as used in end use practice shall also be allowed.  
If in practice different types of adhesive are used, test specimens with each of the different adhesives shall be 
prepared.  
NOTE Some floorings may also be tested without attachment (e.g. adhesive).  DRS 540: 2023 
43                ©RSB 2023- All rights reserved 
 B.2.3 Standard substrates for construction products excluding floorings 
5.3.1 A list of standard substrates is given in Table 1.  
5.3.2 The choice of the substrate for the test specimens shall be made in view of the field of application of test 
results, taking into account the end use substrate and the following rules which apply together:  
5.3.2.1 Each standard substrate represents end use substrates which have a density of at least 75 % of the 
nominal value of the density of that standard substrate.  
5.3.2.2 Standard substrates of classes A1 and A2-s1,d0 represent end use substrates of classes A1 and A2-
s1,d0 only.  
5.3.2.3 The standard particleboard substrate and the standard plywood substrate represents end use wood 
based substrates and also any end use substrate of classes A1 and A2-s1,d0.  
5.3.2.4 The standard gypsum plasterboard substrate is representative of end use gypsum plasterboard 
substrates and also any end use substrate of classes A1 and A2-s1,d0. The standard calcium silicate board 
substrate is not representative of a gypsum plasterboard end use substrate.  
5.3.2.5 The standard steel sheet substrate is only representative of end use metal substrates with a melting 
point equal to or greater than 1 000 °C.  
5.3.2.6 The standard aluminium sheet substrate is only representative of end use metal substrates with a 
melting point equal to or greater than 500 °C.  
5.3.2.7 Where in the end use of a surface product an air gap is incorporated, this shall be reproduced as part 
of the test specimens up to a maximum depth of 25 mm, unless a higher value is specified in the applicable 
test standard.  
5.3.2.8 For a surface product, where there are layers behind the immediate substrate which can influence the 
performance of the product, e.g. an insulating material behind a painted steel sheet, the surface product 
together with its immediate substrate and the additional layers shall be representative of the end use 
application and shall be included in the test specimens. 
5.3.2.9 Surface products with end use substrates not represented by a standard substrate shall be tested in 
end use condition.  
5.3.2.10 The method of attachment (e.g. adhesive) of surface products shall be representative of end use 
application.  
The method of attachment in end use practice shall be reproduced in the preparation of the test specimens, 
i.e. end use adhesive and end use quantities, etc. If the order in which the attachments are conducted is 
known, this shall also be reproduced in the test specimens, e.g. if in end use practice the adhesive is applied 
to the substrate and not to the surface product, then it shall be applied to the substrate during the test 
specimen preparation. The same or greater time for curing and drying as used in end use practice shall also 
be allowed. 
  
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 Annex C 
(normative)  
 
Thermocouple designations 
C.1 Thermocouple designations 
When a thermocouple is identified by the materials of its conductors, the positive conductor shall be listed first, 
thus: ‘positive conductor / negative conductor’. 
The positive conductor is the conductor having a positive electric potential with respect to the other conductor 
when the measuring junction is at a higher temperature than the reference junction.  
Table 1 lists the thermocouple types for which EMFs are specified in this standard. Each letter designation of 
the table identifies the EMF-temperature reference function in the Tables 2 to 
11. The designation may be applied to any thermocouple conforming to the relevant function within the stated 
tolerances specified in Clause 5, regardless of its composition. 
Conformity with alloy specification listed in this clause does not guarantee conformity with the EMF-
temperature relationship of this standard. DRS 540: 2023 
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4 EMF – Temperature reference functions  
The temperature and EMF relationships of this standard are defined by reference functions  which give EMF, 
E/µV, as a function of the temperature, t90/°C, with a reference temperature of 0 °C.  
The reference function of polynomial form for each type of thermocouple, except for Type K in  the 
temperature range from 0 °C to 1 300 °C, is defined by the following equation. 
 
 
 
 
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 where 
E is EMF, expressed in microvolts (µV); 
t90 is ITS-90 temperature, expressed in degrees Celsius (°C); 
ai is the ith coefficient of the polynomial; 
n is the order of the polynomial. 
The values of ai and n are dependent on the type of thermocouple and temperature range.  
Those for each thermocouple are given in the Tables 2 to 11. 
 
 
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C.2 Thermocouple tolerances 
Thermocouple tolerances shall be as specified in Table 12. Users are cautioned that the  
tolerances in Table 12 apply to new wire only and do not allow for changes in the EMF which  may occur with 
use. 
The temperature limits referred to in Table 12 are not necessarily recommended operating  temperature limits. 
Guidance on operating temperature limits is given in Annex C 
For the purpose of testing there should be no discontinuity of conductors between the measuring and the 
reference junction. 
 
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 Annex D 
(informative)  
 
Precision of test method 
D.1 General remarks and results 
The determination of the precision of the test method is based on the results of the SBI round robin test 
series, performed in 1997 and in 2015-2016. The 1997 round robin was conducted by 15 laboratories, testing 
30 products three times. The products of the 1997 round robin are presented in Table B.1. The products of the 
2015-2016 round robin kindly made available by EGOLF are presented in Table B.2.  
The statistical analysis was performed according to ISO 5725-1 and ISO 5725-2 on the continuous 
parameters ( FIGRA 0,2MJ, FIGRA 0,4MJ, THR600s, SMOGRA and TSP600s). No statistical analysis was performed on the 
pass-fail parameters.  
Table B.1 — Products tested in the SBI round robin (1997)  
Code Product Thickness Density Surface 
weight 
 
 (Products are not fire retardant 
treated,unless specified as such 
(with 'FR')) mm 
 kg/m3 
 g/m2 
 
M01 Paper-faced gypsum plasterboard 13 700  
M02 FR PVC 3 1 180  
M03 FR XPS 40 32  
M04 Alu/paper foil faced PUR foam panel 40 PUR: 40  
M05 Spruce laths (joinery timber), 
varnished 10 380  
M06 FR chip board 12 780  
M07 FR PC panel, 3-layered 16 175  
M08 Painted paper-faced gypsum plaster 
board 13 700 Paint: 145 
M09 Paper wall covering on gypsum 
pl.board 13 Gyps.: 700 Paper: 200 
M10 PVC wall carpet on gypsum pl.board 13 Gyps.: 700 PVC: 1 500 
M11 Plastic-faced steel sheet on mineral 
wool 0,15 + 1 + 
50 Wool: 160  
M12 Spruce laths (joinery timber), 
unvarnished 10 450   
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 M13 Gypsum plasterboard on polystyrene  13 + 100 EPS: 20  
M14 Phenolic foam 40   
M15 Intumescent coat on particle board 12 700 Paint: 500 
M16 Melamine faced MDF board 12 MDF: 750 Melamine: 
120 
M17 PVC water pipe diam.: 32; d: 
2   
M18 PVC covered electric cables    
M19 Unfaced rockwool 50 145  
M20 Melamine faced particle board 12 680  
M21 Steel sheet on EPS 0,5 + 100 EPS: 20  
M22 Ordinary particle board 12 700  
M23 Ordinary plywood (birch) 12 650  
M24 Paper wall covering on particle board  12  Paper: 200 
M25 Medium density fibreboard (1) 12 700  
M26 Low density fibreboard 12 250  
Code Product Thickness Density Surface 
weight 
M27 Gypsum plaster board on FR PUR 13 + 87 PUR: 38  
M28 Painted acoustic mineral fibre tiles 18 Wool: 220  
M29 Textile wall paper on CaSi board 10 CaSi: 875 Textile: 400 
M30 Paper-faced glass wool 100 18 90 
 
 
 
 
 
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Table B.2 — Products tested in the SBI round robin (2015–2016)  
Product  Thickness  Density  Square 
density  Mounting  
Non-fire-retardant 
treated particle board  12 mm  680 kg/m3 -  Without joints and no air 
gap  
Decorative paper 
based wall paper glued 
on plasterboard     Without joints and no air 
gap  
Plasterboard  12,5 mm  700 kg/m3 -  
Wallpaper  0,24 mm  -  160 g/m2 
Wallpaper glue  -  -  250 g/m2 
D.2 Calculation of test results 
The continuous parameters were calculated from the test data using the calculations given in  
Annex A of this document. However, since parts of the test and calculation procedures have been amended 
after the 1997 test series, a part of the 1997 test data does not meet the requirements given in Annex A. 
Therefore, the calculations performed with the 1997 test data are based on the method described in Annex A 
with the exception of the deviations given in a) to f). These deviations result in a larger set of data being 
available for the statistical analysis. The precision of the method calculated on the basis of this larger data set 
is expected to be relatively pessimistic. 
a) Check of thermocouples. The round robin was carried out with two compulsory and different thermocouples 
instead of three. The requirement used for the two thermocouples was a maximum difference from their 
average temperature of 2 % in a maximum of 20 sampling points. 
b) Synchronization. For tests that did not meet the synchronization requirements of Annex A, the 
synchronization was continued to the time t = 420 s, with decreased limit values equal to a drop of 1,5 K in 
temperature, 0,03 % for increase of O2 and 0,012 % drop of CO2.  
c) Burner switch response time. Only tests with a determining FIGRA or SMOGRA time within the first minute 
and a burner response time higher than 15 s were omitted. 
d) Smoke measurement. Only tests in which the light signal returns to less than 90 %, were omitted. 
e) Miscellaneous requirements. The other requirements for disregarding a test were not used in this analysis, 
e.g. return of the O2 or CO2 signal to the start level. 
f) Test period. Because of the shorter test period, all calculations were based upon values up to the time t = 1 
470 s.  
©RSB 2023- All rights reserved                  56 
 For the 2015-2016 round robin, the entire procedure of EN 13823:2010+A1:2014 was followed. 
D.3 Statistical analysis 
The calculation and the statistical analyses are based on algorithms only, which means that omission of 
outliers is based upon the numerical technique according to ISO 5725-2:1994, 7.3.2.  
Cochran's test is repeated a maximum of four times, where the standard recommends a maximum of two 
times. With the fourth repetition there were still some laboratories, which were omitted for the SMOGRA value. 
D.4 Statistical results 
The statistical means (m) and standard deviations for repeatability and reproducibility (sr and sR) are given in 
Table B.4 per parameter for all 30 products tested. 
Also added are the standard deviations relative to the mean values (sr/m and sR /m). Although not fully 
statistically justifiable the average sr /m and average sR /m give an indication of the precision of the method. 
In Table B.3 these averages are presented excluding the sr /m and sR /mvalues where the mean value is very 
small 1.  
Table B.5 and Table B.6 give the sr/m and sR /m for two materials. The results are kindly shared by EGOLF, 
organizer of the round robin exercise that lies on the basis of these results. 
 
 
 
 
 
 
 
 
 
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 Annex E 
(informative)  
 
Calibration procedures 
E.1 Procedures for separate pieces of equipment 
E.1.1 General 
Instruments shall be maintained and calibrated in accordance with the manufacturer's specification. 
Gas concentration percentages are represented by 
 
E.1.2 Oxygen analyser adjustment 
The oxygen analyser shall be adjusted for zero and span, each day on which tests are performed.  
The span width shall be within 0,04 % of the width defined by the calibration gases used, and expressed as % 
VO2/Vair. The analyser output for dried ambient air shall be (20,95 ± 0,01) %. A possible procedure to 
perform the adjustment is given in D.1.2.  
E.1.3 Oxygen analyser output noise and drift 
E.1.3.1 General 
The noise and drift of the oxygen analyser output using the data acquisition system shall be checked after set 
up, maintenance, repair or replacement of the oxygen analyser or other major components of the gas analysis 
system and at least every six months. 
E.1.3.2 Procedure 
The procedure for checking the noise and drift of the oxygen analyser output shall be as follows: 
Range of analyser should be at least 16 Vol% to 21 Vol%. 
a) Calibrate the analysers. 
b) Set the volume flow in the exhaust duct to (0,60 ± 0,05) m3/s. 
 
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 c) Switch to sampling air from the exhaust duct with the same flow rate, pressure and drying procedure as 
for sample gases. When the analyser reaches equilibrium, adjust the analyser output to (20,95 ± 0,01) %. 
d) Start recording the oxygen analyser output at 3 s intervals for a period of 30 min. 
e) Determine the drift by use of the least squares fitting procedure to fit a straight line through the data 
points. The absolute value of the difference between the readings at 0 min and at 30 min of this linear 
trend line represents the drift. 
f) Determine the noise by computing the root-mean-square (RMS) deviation around the linear trend line. 
E.1.3.3 Criteria 
The sum of drift and noise (both taken as positive values) shall be not more than 0,01 % (VO2/Vair). 
E.1.3.4 Calibration report 
The calibration report shall include the following information: 
a) the graphs of O2(t) in % VO2/Vair;  
b) the noise and drift values calculated according to C.1.3.2, d) and e) in % VO2/Vair.  
E.1.4 Carbon dioxide analyser adjustment 
The carbon dioxide analyser shall be adjusted for zero and span each day on which tests are performed. The 
span width shall be within 0,1 % VCO2/Vair of the width defined by the calibration gases used. The analyser 
output for carbon dioxide-free nitrogen gas shall be (0,00 ± 0,01) %.  
Alternatively, the analyser can use dry ambient air and the output shall be (0,04 ± 0,01) %. A possible 
procedure to perform the adjustment is given in D.1.3.  
E.1.5 Light system calibration 
E.1.5.1 General 
The light system calibration shall be performed before a test is conducted after set up, maintenance, repair or 
replacement of the smoke measurement system holder or other major components of the exhaust system and 
at least every six months. The calibration consists of two parts: an output stability check and an optical filter 
check. 
E.1.5.2 Stability check 
Perform the following steps with the measuring equipment operating and with the trolley (excluding specimen, 
including backing boards) in the frame, under the hood. DRS 540: 2023 
65                ©RSB 2023- All rights reserved 
 a) Set the volume flow of the exhaust to: V298 = (0,60 ± 0,05) m3/s [calculated in accordance with A.5.1.1 
a)]. 
b) Start the time measurement and record the signal from the light receiver for a period of 30 min. 
c) Determine the drift by use of a least squares fitting procedure to fit a straight line through the data points. 
The absolute value of the difference between the readings at 0 min and at 30 min of this linear trend line 
represents the drift. 
d) Determine the noise by computing the root-mean-square (RMS) deviation around the linear trend line. 
Criterion: Both noise and drift shall be less than 0,5 % of the start value 
E.1.5.3 Optical filter check 
The light system shall be calibrated with at least five neutral density filters in the optical density range of 0,05 
to 2,0. The optical density calculated with the measured light receiver signal shall be within either ± 5 % or ± 
0,01 of the actual value of the filters, whichever represents a wider tolerance. A possible procedure to perform 
the calibration is given in D.1.5. The neutral density filters used for calibration shall have dispersed attenuant. 
Coated filters shall not be used. 
E.2 System response calibrations 
E.2.1 Burner switch response time 
The burner switch response time is the difference between tup and tdown, where: 
tup   is the time of the first data point at which the oxygen concentration has passed the “90% burner 
output level” in the upwards direction after t = 270 s; and 
tdown  is the time of the first data point thereafter at which the oxygen concentration has passed the same 
level in the downwards direction. 
 
NOTE 1 The data are synchronized to t = 300 s. Time tup is equal to 300 s or 303 s, therefore tdown is never later than t = 
315 s. Meeting the criterion is of major importance for the correct assessment of FIGRA and SMOGRA values. 
 
©RSB 2023- All rights reserved                  66 
 During the switch from auxiliary (secondary) burner to main (primary) burner (at t approximately 300 s), for a 
short time, the total heat output from both burners is lower than the standard heat output of one burner. As a 
consequence, the heat release rate has a dip and the oxygen level has a peak (see Figure C.1). The peak in 
xO2 is about 25 % to 50 % of the contribution of one burner. The width of the peak should be small since this 
“missing” heat output is subtracted from the heat output of the specimen as described below. The peak width 
is measured at a level of 90 % of the normal burner contribution, and is called the burner switch response 
time. In the example presented in Figure C.1, the response time is 9 s. 
NOTE 2 The 90 % burner output level is calculated as 90 % of the step from the test start level to the base line level, 
added to the test start level. The oxygen test start level used here is the average oxygen concentration before ignition of 
the burners (30 s ≤ t ≤ 90 s). The oxygen base line level is the average oxygen concentration during burning of the 
auxiliary (secondary) burner (210 s ≤ t ≤ 270 s). DRS 540: 2023 
67                ©RSB 2023- All rights reserved 
  
 
 
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 NOTE 3 Main events: (1) auxiliary (secondary) burner on at t approximately 120 s; (2) switch from auxiliary 
(secondary) burner to main (primary) burner at t approximately 300 s. The time interval around  
t = 300 s is magnified in Figure C.1 b). The calculated burner response time is 9 s in this case. 
E.2.2 Burner heat output step calibration 
E.2.2.1 General 
This calibration procedure uses the standard burner at three different levels of heat output. It is used to 
determine the response and delay time of the gas analysers, the burner switch response time, the 
thermocouples' response time and the conversion factor for calculation of the heat release rate. This 
calibration procedure shall be performed at least once a month or after 30 tests, whichever occurs first. 
NOTE As part of the system calibration process, the response times of the gas analysers are determined 
using relatively large step changes in heat release of around 30 kW and 60 kW, which represents changes in 
oxygen concentrations of about 0,3 % (v/v) and 0,6 % (v/v). The measured response times are influenced by 
preset damping factors of the analysers. 
It should be noted that some gas analysers utilize additional damping factors when measuring relatively small 
(typically in the order of 100 ppm) changes in gas concentration. This additional damping factor can be used 
to eliminate noise but the bandwidth should not be so large as to adversely affect the response time of the 
system. 
E.2.2.2 Procedure 
Perform the following steps with the measuring equipment operating and with the trolley (excluding specimen, 
including backing boards) in the frame, under the hood. 
a) Set the volume flow of the exhaust to: V298 = (0,60 ± 0,05) m3/s [calculated in accordance with A.5.1.1 
a)]. This volume flow shall be between 0,65 m3/s and 0,50 m3/s during the total calibration period. 
b) Record the temperatures T1, T2 and T3 in the exhaust duct and the ambient temperature during at least 
300 s. The ambient temperature shall be within (20 ± 10) °C, and the temperatures in the duct shall not 
differ by more than 4 °C from the ambient temperature. 
c) Record the pre-test conditions on the record sheet. The data to be recorded are given in 8.3.2.  
d) Start the time measurement and the automatic recording of data: at this point t = 0 s, by definition. The 
data to be recorded every 3 s are t, mgas, xO2, xCO2, Δp and T0 to T3, according to 8.4.  
e) Ignite the auxiliary (secondary) burner and adjust the propane mass flow in accordance with Table C.1 
within the first 5 s of each step. 
 
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69                ©RSB 2023- All rights reserved 
  
 
f) Switch the propane supply from the auxiliary (secondary) burner to the main (primary) burner, and adjust 
the propane mass flow in accordance with Table C.2 within the first 5 s of each step. 
 
g) Stop the automatic recording of data at the end of step 6. 
h) Record the end of test conditions. The data to be recorded are given in 8.3.5.  
NOTE 1 The burner produces approximately 0 kW, 30 kW and 93 kW at the requested propane mass flow levels. 
NOTE 2 The margins used in the mass flow settings are larger than in the test procedure to allow for fast adjustments in 
the mass flow. 
 
 
 
 
 
 
 
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E.2.2.3 C.2.2.3Calculations  
Based on the unshifted data, calculate:  
a)  for each step, except step 3:  
1. tgas the start time of the step as the time of the first data point at which the propane flow has changed 
by 100 mg/s in comparison with the mean value in the last 2 min of the previous step;  
2. tT the time of the first data point at which the temperature Tms has changed 2,5 K in comparison with 
the mean value in the last 2 min of the previous step;  
3. tO2 the time of the first data point at which the oxygen concentration has changed 0,05 % in 
comparison with the mean value in the last 2 min of the previous step;  
4. tCO2 the time of the first data point at which the carbon dioxide concentration has changed 0,02 % in 
comparison with the mean value in the last 2 min of the previous step;  
5. tO2,10 % the time of the first data point at which the oxygen concentration has reached 10 % of its 
deflection using the mean values in the last 2 min of the previous and the current step;  
6. tO2,90 % analogous to tO2,10 %, however for 90 % instead of 10 % deflection;  
7. tCO2,10 % the time of the first data point at which the carbon dioxide concentration has reached 10 % of 
its deflection using the mean values in the last 2 min of the previous and the current step;  
8. tCO2,90 % analogous to tCO2,10 %, however for 90 % instead of 10 % deflection;  
9. tT,10 % the time of the first data point at which the temperature Tms has reached 10 % of its deflection 
using the mean value in the last 15 s of the previous step and the mean value between 15 s and 30 s 
after the start of the current step;  
10. tT,75 % analogous to tT,10 %, however for 75 % instead of 10 % deflection;  
b) the delay time of the oxygen analyser as the mean of tO2 – tT found for steps 4, 5 and 6;  
c) the delay time of the carbon dioxide analyser as the mean of tCO2 – tT found for steps 4, 5 and 6;  
d) the response time of the oxygen analyser as the mean of tO2,90 % – tO2,10 % found for steps 4, 5 and 6;  
e) the response time of the carbon dioxide analyser as the mean of tCO2,90 % – tCO2,10 % found for steps 4, 5 
and 6;  
f) the burner switch response time as specified in C.2.1;  DRS 540: 2023 
71                ©RSB 2023- All rights reserved 
 g) the temperature response time as the mean of tT,75 % – tT,10 % found for steps 2, 4, 5 and 6;  
h) qgas(t) and qgas,30s(t), in accordance with A.7;  
i) the mean value of qgas(t) according to h) during the two minutes in the middle (starting 30 s after switching 
to the next gas flow value) of steps 2, 3 and 5 ( qgas,step2, qgas,step3 and qgas,step5).  
Shift the O 2 and CO 2 data backwards in time in accordance with the analyser delay times found, and 
calculate:  
j) HRR(t), equal to HRRtotal(t) in accordance with A.5.1.1 but with E = 16 800 kJ/m3 (value for propane);  
k) HRR30s(t), in accordance with A.5.1.4, using HRR(t) in accordance with j);  
l) the average values of HRR(t) in accordance with k) during the two minutes in the middle of steps 2, 3 and 
5 (HRRstep2, HRRstep3 and HRRstep5);  
m) the flow profile factor kt,qgas, as: 
 
NOTE 1 The delay and response time of the analysers in step 2 are used as a check. The difference with the time delays 
in steps 4, 5 and 6 can point to additional time delay(s) in the propane supply system.  
NOTE 2 The temperature response time is calculated to check for dysfunction of, and soot deposits on the thermocouples. 
The criterion for the thermocouple response time takes account of the influence of the thermal response of the exhaust 
system as a whole. 
 
 
 
 
 
 
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E.2.2.4 Criteria  
The following criteria shall be met:  
a) the delay time of both analysers shall not exceed 30 s;  
b) the response time of both analysers shall not exceed 12 s;  
c) the burner switch response time shall not exceed 12 s;  
d) the temperature response time shall not exceed 6 s;  
e) the equipment response shall meet the criteria of A.3.2 and A.3.3; the end values in A.3.2 and A.3.3 shall 
be taken as the mean over the last 30 s of step 6;  
f) the ratio qgas30s(t)/HRR30s(t) shall continuously be within (100 ± 5) % during the intervals between 40 s and 
160 s after the start of steps 2, 3, 4 and 5. For the start of steps 2, 4 and 5, tT is used; the start of step 3 is 
taken as t = 300 s;  
g) the averages HRRstep2 and HRRstep3 according to C.2.2.3 shall not differ by more than 0,5 kW.  
E.2.2.5 Calibration report  
The calibration report shall include the following information:  
a) the graphs of qgas(t)/HRR(t) and qgas,30s (t)/HRR30s(t);  
b) the maximum and minimum of the ratio qgas30s (t)/HRR30s(t) during each of the four intervals according to 
C.2.2.4, f);  
c) the delay and response times of both analysers;  
d) the burner switch response time;  
e) the temperature response time;  
f) the value of qgas,stepx, and HRRstepx, for steps 2, 3 and 5;  
g) the value of kt used in the HRR(t) calculation;  
h) the value of kt,qgas.  DRS 540: 2023 
73                ©RSB 2023- All rights reserved 
 E.2.3 Heptane calibration 
E.2.3.1 General  
The calibration shall be performed before a test is conducted after set up, maintenance, repair or replacement 
of the measurement system holder or other major components of the exhaust system and at least once a 
year. The measurements are made using:  
a) circular open steel fuel tray of internal diameter (350 ± 5) mm, with an internal wall height of 152 mm and 
a wall thickness of 3 mm; and  
b) n-heptane (>99 % purity).  
E.2.3.2 Procedure  
Perform the following steps with the measuring equipment operating and with the trolley (excluding specimen, 
including backing boards) in the frame, under the hood.  
a) Set the volume flow of the exhaust to: V298 = (0,60 ± 0,05) m3/s (calculated in accordance with A.5.1.1 a)). 
This volume flow shall be within the range 0,65 m3/s to 0,50 m3/s during the total calibration period.  
b) Record the ambient temperature T0 and the temperatures T1, T2 and T3 in the exhaust duct during at least 
300 s. Measure the surface temperature of the fuel tray. The ambient temperature shall be within (20 ± 
10) °C. The temperatures in the duct and the temperature of the fuel tray shall not differ by more than 4 
°C from the ambient temperature.  
c) The fuel tray is placed over the trolley platform, on a standard calcium silicate board with dimensions of 
400 mm × 400 mm. Supports of 100 mm high raise the calcium silicate board above the conduit that runs 
diagonally across the floor of the trolley. The fuel tray is positioned such that the distance between the 
internal corner of the specimen holder and the side wall of the fuel tray is 500 mm. When positioned 
correctly, the side wall of the fuel tray is at least 300 mm from both the back and side panels.  
d) Pour (2 000 ± 10) g of water into the fuel tray.  
e) Record the pre-test conditions on the record sheet. The data to be recorded are given in 8.3.2.  
f) Start the time measurement and the automatic recording of data: at this point t = t0, by definition. The data 
to be recorded every 3 s are t, mgas, xO2, xCO2, Δp, T0 to T3 and the signal from the light receiver, in 
accordance with 8.4.  
g) Wait at least 2 min then gently pour (2 840 ± 10) g of n-heptane onto the water in the fuel tray.  
h) Wait at least 1 min, then ignite the n-heptane ( t1).  
i) When the burning ceases, the data recording is continued for a further 5 min and then stopped ( t2).  
j) Record the end of test conditions. The data to be recorded are given in 8.3.5.   
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 E.2.3.3 Calculations  
Calculate the following quantities:  
a) the total smoke production TSP in accordance with A.6 over the time interval between t1 and t2. The TSP 
is then divided by the mass of fuel used ( m);  
b) the total heat release THR in accordance with A.5 over the time interval between t1 and t2. The heat 
release calculation (A.5.1.1) shall be carried out using an E value of 16 500 kJ/m3 (value for n-heptane). 
The THR is then divided by the mass of fuel used ( m);  
c) the flow profile factor kt,qheptane, as:  
 
 
E.2.3.4 Criteria  
The following criteria shall be met:  
a) the ratio THR/m (MJ/kg) shall be 44,56 MJ/kg ± 5 %;  
b) at t2, the signal from the light receiver shall be within 1 % of its initial value (i.e. between 99 % and 101 % 
of I(30 s…90 s));  
c) the equipment response shall meet the criteria of A.3.2 and A.3.3.  
The ratio TSP/m (m2/kg) can be used as an indication for the performance of the smoke measurement 
system. Its value should be (125 ± 25) m2/kg.  
E.2.3.5 Calibration report  
The calibration report shall include the following information: a)  the graphs of 
SPR(t) and HRR(t);  
a) the ratios TSP/m and THR/m;  
b) the values of kt used in the HRR(t) calculation and of kt,qheptane.  
DRS 540: 2023 
75                ©RSB 2023- All rights reserved 
 E.2.4 Velocity profile factor kt,v 
E.2.4.1 General  
The kt,v factor shall be measured after set up, maintenance, repair or replacement of the hemispherical probe 
or other major components of the exhaust system and at least every year. The measurements are made using 
a pitot tube or a hot wire anemometer.  
E.2.4.2 Measurement specifications  
a) The equipment shall be run on a damping setting that is sufficiently high to obtain a steady reading.  
b) When inserted into the exhaust duct the measurement probe shall be mechanically fixed into position, 
rather than held by hand. The horizontal or vertical positioning of the probe (whichever is required) and 
the right angles to the duct shall be checked.  
c) The entry ports not used by the anemometer shall be closed.  
d) The gas velocity shall be measured 20 times in every measurement position, ten times when traversing 
outwards from the centre, and ten times when traversing inwards to the centre. It is not necessary to 
record the 10 measurements if a suitable anemometer is used which automatically measures and 
calculates a suitable mean value.  
The measurement positions on a single radius are at the following distances from the wall, expressed as a 
fraction of the radius (taken from ISO 3966:2008): 0,038; 0,153; 0,305; 0,434; 0,722 and 1,000 (centre). The 
positions are indicated in Figure C.2. 
NOTE For the duct diameter used (315 mm), these positions are (in millimetres from the centre): 0 mm; 43,7 mm; 89,1 
mm; 109,5 mm; 133,4 mm; 151,5 mm.  
©RSB 2023- All rights reserved                  76 
  
 
E.2.4.3 Actions  
Perform the following steps:  
a) Set the volume flow of the exhaust to: V298 = (0,60 ± 0,05) m3/s [as calculated in accordance with A.5.1.1, 
a)].  
b) Record the temperatures T1, T2 and T3 in the exhaust duct and the ambient temperature for at least 300 s. 
The ambient temperature shall be within (20 ± 10) °C, and the temperatures in the duct shall not differ by 
more than 4 °C from the ambient temperature.  
c) Measure the gas velocity in all measurement positions, six positions per entry port.  
d) Calculate the gas velocity at all measurement positions as the mean of the 20 values measured, giving Vc 
for the centre position and five Vn values for the five other positions for each entry port.  
NOTE  As a result, the velocity profile is measured and calculated both horizontally and vertically over the full 
diameter.  
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77                ©RSB 2023- All rights reserved 
 E.2.4.4 Calculation of kt,v 
For a given radius the mean velocity at a radius n is given by vN, which is the mean of the four vn values 
measured. The velocity at the centre position is given by vC, which is the mean of the four vc values 
measured. The profile factor kt,v is then:  
 
E.2.4.5 Measurement report  
The measurement report shall include the following information:  
a) the velocity profile based on the mean vn at five radii and vc, separately for each entry port (a vertical and 
a horizontal cross-section);  
b) the values of four vn's, four vc's, vN, vC and the resulting kt,v.  
E.2.5 Flow factor kt 
The kt factor (used for the calculation of the heat release rate in A.5.1) shall be calculated as the average of 
the three values kt,v, kt,qgas, and kt,qheptane which shall meet the following criteria:  
 kt = (kt,v + kt,qgas + kt,qheptane) / 3   (C.6)  
Criteria:  
| (kt – kt,v) / kt | ≤ 5 %  
| (kt – kt,qgas) / kt | ≤ 5 %  
| (kt – kt,qheptane) / kt | ≤ 5 %  
Where: 
kt,v is the velocity profile factor measured in accordance with C.2.4;  
kt,qgas is the flow profile factor calculated in accordance with C.2.2;  
kt,qheptane  is the flow profile factor calculated in accordance with C.2.3.  
Historical development of each of the kt values should be monitored. Changes can be used as a warning 
signal that an overhaul of the duct system equipment and instrumentation may be required.  
 
 
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 Annex F 
(informative)  
 
Calibration procedures 
F.1 Procedures for separate pieces of equipment 
F.1.1 General 
This clause includes calibration procedures that meet the performance-based calibration requirement they 
referto.  
Gas concentration percentages are represented by 100 VO2/Vair and 100 V CO2/Vair.  
F.1.2 Oxygen analyser adjustment 
The oxygen analyser may be adjusted using the following procedure.  
a) For zeroing, feed the analyser with oxygen-free nitrogen gas, with the same flow rate and pressure as for 
sample gases. When the analyser reaches equilibrium, adjust the analyser output to (0,00 ± 0,01) %.  
b) For the span calibration either dried ambient air or a specified gas with an oxygen content of (21,0 ± 0,1) 
% may be used. If ambient air is used for the span calibration the exhaust system should be running at 
(0,6 ± 0,05) m3/s during the entire calibration. If a specified gas is used, the exhaust system is not 
needed. When the analyser reaches equilibrium, adjust the analyser output to (20,95 ± 0,01) % if dried air 
is used and to within 0,01 % of the actual oxygen content if the specified gas is used.  
NOTE For certain analysers the terms zero and span can have a different meaning, e.g. for analysers with a smaller range 
than 0 % to 21 % oxygen. In these cases, calibration gases within the range of the analysers can be used.  
F.1.3 Carbon dioxide analyser adjustment 
The carbon dioxide analyser may be adjusted using the following procedure.  
a) For zeroing, feed the analyser with carbon dioxide-free nitrogen gas, with the same flow rate and pressure 
as for sample gases. When the analyser reaches equilibrium, adjust the analyser output to (0,00 ± 0,01) 
%.  
b) For span calibration a specified gas with a carbon dioxide content between 5 % and 10 % should be used. 
Feed the analyser with the gas, with the same flow rate and pressure as for sample gases. When the 
analyser reaches equilibrium, adjust the analyser output to the carbon dioxide content of the specified gas 
± 0,01 %.  DRS 540: 2023 
79                ©RSB 2023- All rights reserved 
 F.1.4 Check of propane mass flow controller 
F.1.4.1 General  
The accuracy of the mass flow controller may be checked by using a single cylinder of propane and the main 
(primary) burner at the propane mass flow rate as used during standard tests (647 ± 10) mg/s. The gas usage 
rate is determined from the initial and final mass of the gas cylinder. Use a balance or weighing platform with 
an accuracy of 5 g or better.  
F.1.4.2 .4.2Procedure  
a) Place the cylinder on the weighing platform and connect it to the supply system.  
b) Set up the test facility as in a standard calibration test with backing boards fitted. Ignite the main (primary) 
burner and adjust the gas supply to (647 ± 10) mg/s, to have the main (primary) burner running at the 
standard rate as used during standard tests.  
c) Record the mass of the cylinder and simultaneously start a timing device.  
d) After (3 600 ± 30) s, again record the mass of the cylinder and simultaneously stop the timing device.  
e) Determine the average rate of usage of gas in milligrams per second.  
D.1.4.3Criterion  
The average rate of usage of gas set in b) and determined in e) should be equal to within 6 mg/s.  
F.1.5 Optical filter check 
F.1.5.1 General  
The light system may be calibrated using the following procedure.  
F.1.5.2 Procedures  
Perform the following steps with the measuring equipment operating and with the trolley (excluding specimen, 
including backing boards) in the frame, under the hood.  
a) Place a light blocking insert into the filter holder and adjust to zero.  
b) Remove the light blocking insert and adjust the signal from the light receiver to 100 %.  
c) Start the time measurement and record the signal from the light receiver for a period of 2 min.  
d) Introduce one of the following filters with optical density ( d) equal to 0,1, 0,3, 0,5, 0,8, 1,0 and 2,0 and 
record the corresponding signal for at least 1 min.   
©RSB 2023- All rights reserved                  80 
 e) Repeat step d) for the other filters.  
f) Stop the data acquisition and calculate the mean transmission values for all filters.  
F.1.5.3 Criterion  
Each d value calculated from the mean transmission value [ d = – log( I)] should be within ± 5 % or within ± 
0,01 of the theoretical d value of the filter.  
NOTE The theoretical transmission values for the given d values 0,1, 0,3, 0,5, 0,8, 1,0 and 2,0 using the given equation 
are 79,43 %, 50,12 %, 31,62 %, 15,85 %, 10 % and 1 %.  
F.2 Check of the thermal attack on the specimens 
F.2.1 General 
The repeatability of the heat flux on the specimens should be checked after set up, maintenance, repair or 
replacement of the main (primary) burner or other major components that may influence the flames of the 
burner, by measuring the heat flux in the following three positions on the long wing:  
—  position 1: 8 cm from the corner and 16 cm from the upper edge of the burner;  
—  position 2: 8 cm from the corner and 75 cm from the upper edge of the burner;  
—  position 3: 20 cm from the corner and 30 cm from the upper edge of the burner.  
For regular calibrations, or if there is a modification of the burner (for example: the old sand is replaced by a 
new sand), a measurement of the heat flux at position 3 is sufficient.  
This check is performed with a large wing calcium silicate backing board (see 4.4.10) having three holes 
(diameter = 26 mm) at the positions given.  
F.2.2 Procedure 
Before ignition of the burner, place a heat flux meter in one of the holes in the long wing backing board (with 
the small wing backing board being also in place), and close the other holes.  
The heat flux meter should be a 25,4 mm diameter Schmidt-Boelter which is calibrated between 0 kW/m2 and 
100 kW/m2. The flux meter should be cooled by water at a temperature above 20 °C. The flux meter black 
body surface should be on the backing board surface.  
With the SBI apparatus working under normal conditions (see 8.2), record the heat flux for 5 min after the 
ignition of the burner. Then calculate the mean of the heat flux measured between 240 s and 300 s after 
ignition.  
After set up, maintenance, repair or replacement of the main (primary) burner or other major components that 
may influence the flames of the burner, repeat the measurement five times. Calculate the mean of the results 
of the five measurements for each position. The relative standard deviation should be less than 4 %.  DRS 540: 2023 
81                ©RSB 2023- All rights reserved 
 For regular calibrations (in position 3), one measurement is sufficient. If the deviation between this result and 
the mean of the means of the five replicant measurements is more than 4 %, check the burner or other parts 
of the apparatus and perform a measurement five times in the three positions.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
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 Annex G 
(informative)  
 
Design drawings 
 
 
 
 
 
 
 
DRS 540: 2023 
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 Annex H 
(informative)  
 
Data file format 
For easy exchange of test results, test data should be stored in a standard format. The principal objective is 
that the file should contain all the required information including both visually observed/recorded and 
automatically recorded data. It should be possible to perform all requested calculations and (combined with 
other test results) the assessment of classification.  
The data of a test should be stored in an ASCII-file with twelve tab-separated columns of data. More columns 
(with non-compulsory data) are allowed when they are placed after the compulsory columns, not in between.  
The file should contain a two-line header and additional lines with general information and automatically 
recorded (raw) data per time step. The first header line contains the column header texts:  
a)  general information;  
b) [empty];  
c) time (s);  
d) mgas (mg/s);  
e) Δp (Pa);  
f) light signal (%);  
g) mole percentage of oxygen (%);  
h) mole percentage of CO 2 (%);  
i) T0 (K);  
j) T1 (K);  
k) T2 (K);  
l) T3 (K).  
The second line is not specified (empty by default).  DRS 540: 2023 
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 Subsequent lines contain general information in the first two columns and automatically recorded (raw) data in 
the next ten columns. Only the first 62 lines in columns one and two are used. In columns 3 to 12 this is at 
least 520 lines (1 560 s time interval with a 3 s step).  
The general information (regarding the test, product, laboratory, apparatus, pre-test and end of test conditions, 
and visual observations) is given in column two, with a description of what is presented in column one. The 
row order of the different items is given in the example below.  
The ten columns with automatically recorded data are in accordance with, and in the same order as in 8.4.   
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The data file format presented here only concerns the raw data (before performing the calculations). No file 
format is given for processed data files. However, it is advisable to build the processed data file from the raw 
data file by adding columns and rows at the ends (and not in between). In this way a processed data file can 
easily be used as a raw data input file. 
 
 
 
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 Annex I 
(informative)  
 
Record sheet 
 
 
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 Bibliography 
[1] [1] ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: 
General principles and definitions 
[2] [2] ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results — Part 
2: Basic method for the determination of repeatability and reproducibility of a standard measurement 
method 
[3] [3] ISO 3966:2008, Measurement of fluid flow in closed conduits — Velocity area method using Pitot 
static tubes 
[4] [4] SETTE. BJG, Development of a velocity pressure probe. Fire Mater. 2006 NOV-DEC, 30 (6) pp. 
397–414 
 
 DRS 540: 2022 
 
Price based on 120pages  
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