---

The test flame shall be applied for (1 200⁺¹q ) s, after which it shall be extinguished.

1. Switch on the air input fan and adjust the airflow through the chamber to (8 000 ± 400) l/min

2. Set the volume flow of the exhaust to the predetermined value as stated in 6.6.

NOTE Any specific guidance, i.e. pre test operations from the supplier of the equipment, should be fulfilled before starting a test.

3. Record the duct temperatures and the ambient temperature for at least 300 s. The ambient temperature shall be within the range 5 °С to 40 °С, and the temperatures in the duct shall not differ more than 4 °С from the ambient temperature.

4. Record the pre-test conditions of the air going into the duct (ambient temperature, atmospheric pressure and humidity). Refer to A.3.

5. Start the time measurement and the automatic recording of data. The time of start is t = 0 s, by definition. The data to be recorded are those variables necessary for the calculation of HRR and SPR.

6. At t = 270 s the base line values shall be checked for HRR and transmission value (or corresponding extinction coefficient). If they differ more than 2,0 kW for the HRR or 2 % for the transmission value from the start values, the test shall be stopped and an error analysis should be carried out. This is extremely important to ensure the quality of the HRR and SPR measurement. The start values shall be determined as the average of the first 30 s of the test (between 0 s and 30 s).

7. At t = (300 ± 10) s : Ignite the burner and adjust the propane and air flow rates to the values given in 6.7 in order to have a nominal heat output of 20,5 kW or 30,0 kW as appropriate. Record the time of burner ignition, t_b.

8. Observe the burning behaviour of the cable including any flaming droplets/particles and record the necessary report data to complete the test report according to Clause 8. If the HRR reaches greater than 450 kW the test should be stopped. Extinguishing of the cable is permitted in order to protect the apparatus and its measuring devices.

9. At t = (1 500 ⁺¹°) s: Switch off the propane supply to the burner.

10. At t - (1 530 ± 10) s: Stop the automatic recording of data and if cable burning or glowing continues,

extinguish the fire.

Extensive burning of the cables and flaming outside the top of the rig might require the extinguishment of the test specimen and abortion of the test. If this occurs, it shall be reported together with the time of extinguishment.

The following parameters shall be determined during the test:

• heat release rate as a function of time;

• smoke production rate as a function of time;

• occurrence and duration of flaming droplets/particles.

The fall of flaming droplets or particles shall be recorded within the full 1 200 s of the test when the droplets/particles reach the floor of the test chamber. The following occurrences shall be recorded:

1. the fall of a flaming droplet/particle that remains flaming for not more than 10 s after reaching the floor of the test chamber;

2. the fall of a flaming droplet/particle that remains flaming for more than 10 s after reaching the floor of the test chamber.

7. Determination of parameters derived from the test

   1. Calculation of HRR and SPR parameters

      1. Peak heat release rate value (Peak HRR)

The peak HHR value is defined as the maximum value of HRR_av(t), excluding the burner output, and shall be determined during the whole burner application time starting from ignition of the burner (t_b) to the end of burner application (t_b + 1 200) s. It shall be expressed in kW.

In order to exclude the burner output from the HRR in the calculation of HRR_av(t), the nominal HRR from the burner of 30,0 kW (for Class B1_ca) or 20,5 kW (for Class B2ca, Cea and Dea ) shall be subtracted from the total HRR. All negative HRR values shall be set to zero.

Details of the calculation are given in G.1.

The peak SPR value is defined as the maximum value of SPR_av(t), and shall be determined during the whole burner application time between //.and (t_b + 1 200) s. It shall be expressed in m²/s.

Details of the calculation are given in G.2.

The total heat release value shall be calculated as the integrated value of the HRR, excluding the burner output over a period starting from ignition of the burner (t_b) to the end of burner application (t_b + 1 200 s). If the test has to be stopped early because of too high HRR value, then this value shall not be calculated but a clear record shall be made of this occurrence. Negative values of the HRR, excluding the burner, shall not be included in the integration. It shall be expressed in MJ.

The total smoke production value is calculated as the integrated value of the SPR over a period starting from ignition of the burner (t_b) to the end of burner application (t_b + 1 200 s). If the test has to be stopped early because the HRR value was too high, then this value shall not be calculated but a clear record shall be made of this occurrence. Negative values of the SPR shall not be included in the integration. It is expressed in m².

The FIGRA is defined as the maximum of the quotient HRRav(t) / (t-t_b).

Details of the calculation are given in G.3.

After all cable burning or glowing has ceased or been extinguished, the test sample shall be wiped clean.

All soot shall be ignored if, when wiped off, the original surface is undamaged. Softening or any deformation of the non-metallic material shall also be ignored. The flame spread shall be measured as the extent of the damage. It shall be measured in metres to two decimal places from the bottom edge of the burner to the onset of char. The onset of char shall be determined as follows:

Press against the cable surface with a sharp object, e.g. a knife blade. Where the surface changes from a resilient to a brittle (crumbling) surface, this indicates the onset of char.

7. Test report

   1. General

The written report shall contain a brief description of the overall test set-up. Any deviations from the procedure in this standard shall be stated. The mounting shall be described in detail. As a minimum, the information listed in 8.2 shall be present in each report A clear distinction shall be made between the data provided by the applicant and data determined by the test.

1. The name and address of the testing laboratory;

2. the date and identification number of the report;

3. the name and address of the applicant;

4. the name and address of the sample manufacturer/supplier, if known;

5. the date of test.

1. An identification of the cable tested;

2. a description of the cable tested.

1. The number of this standard (i.e. EN 50399);

2. the number of test pieces;

3. the overall diameter of the test pieces;

4. the method of mounting (i.e. spaced or bundles);

5. the use of a backboard or not;

6. the flame application time (i.e. 20 min);

7. the output of the burner (i.e. 20,5 kW or 30,0 kW).

1. The extent of flame spread (as defined in 7.2);

2. the occurrence or not of flaming droplets and their duration (as determined according to 6.10);

3. HRRav and SPRav graphs as a function of time starting from the beginning of the test (i.e. 300 s before ignition of the burner), excluding the burner output and with any negative values set to zero;

4. any observations made during the test.

The calculated results shall be expressed with the following parameters:

1. the peak HRRav value (as defined in 7.1.1);

2. the peak SPRav value (as defined in 7.1.2);

3. the THR (as defined in 7.1.3) over the period of the application of the flame burner;

4. the TSP (as defined in 7.1.4) over the period of the application of the flame burner;

the FIGRA (as defined in 7.1.5).Key

L = 12 D min.

- General arrangement of test apparatus

Key

1 chamber

Dimensions in millimetres

2 exhaust duct

1. - Schematic of a hood

Dimensions in millimetres

Key

1

2 air flow direction

4 steel plates 395 mm x 400 mm

NOTE 1 Dimensions indicated are for a 400 mm diameter duct.

NOTE 2 A better mixing has been observed with the air flow direction as indicated compared to the opposite direction.

- Typical guide vane

s

4,7

» [ I «1,80 / = 20

Dimensions in millimetres

Key

2

1 to Др instrument

variable length support tubes

3 weld

NOTE Taken from Me Caffrey and Heskestad, Combustion and Flame, 26 (1976) [5].

- Bidirectional prob

e

„P^VD

X Re=—

P

3. -

   / ₄l/2

   І 2Др

   I P ,
   V

   Probe response versus Reynolds number








Key




b) Dual flow




Dimensions in millimetres









































































































exhaust duct




15 holes on down stream side of flow (0 3 mm for arrangement a); 0 2 mm for arrangement b)

)

sample flow

16 0 2 mm holes on down stream side of flow

- Sampling prob

e
































































5. filters

6. gas cooling system

7. membrane pump

8. gas flowmeter




Кеу

1. sampling probe

2. exhaust tube

3. sampling line

4. analysers

NOTE Other gas cooling systems may be used. Cooling may be omitted if the water trap is sufficiently efficient.

Figure 7 - Schematic diagram of sampling lin

e





Figure 8 - Optical system - General arrangement














6 500 ±5 Dimensions in millimetres Key
1	diameter of upright	5	distance between rungs
2	number rungs = 9	6	width
3	diameter of rungs	7	calcium silicate board
4	total height of ladder





































































































Annex A

(normative)

Calculation of heat release

A.1 Volume flow

The volume flow in the exhaust duct, expressed in cubic metres per second, related to atmospheric pressure and an ambient temperature of 25 °С, is given by the equations:

^298 ~ (Лк, x(2 I T_s) (A.1)

/^?298

r₂₉₈ = 22,4(A/^)(A/’/^)’^/2 ,_A~

where

T_s is the gas temperature in the exhaust duct, in K;

T_o = 273,15 K;

Др is the pressure difference measured by the bidirectional probe, in Pa;

p_29S is the air density at 25 °С and atmospheric pressure, in kg/m³;

po is the air density at 0 °С and 0,1 Pa, in kg/m³ (1,293 kg/m³);

A is the cross-sectional area of the exhaust duct, in m²;

k, is the commissioning factor determined according to E.3.4;

k_p is the Reynolds number correction for the bidirectional probe suggested by Me Caffrey and Heskestad [5]. In the exhaust duct, conditions are such that R_e is usually larger than 3 800 hence k_p can be taken as constant and equal to 1,08.

Equation (A.1) assumes that density changes in the combustion gases (related to air) are caused solely by the temperature increase. Corrections due to changed chemical composition or humidity content may be ignored. The calibration constant k, is a combination of the correction factor for the flow profile (A_c),determined by measuring the flow profile inside the exhaust duct along a cross-sectional diameter, and the correction factors from the propane and methanol calibrations (see E.3.4)

A.2 Generated heat effect

A.2.1 Heat release from the ignition source

During the calibration process, the heat release rate from the ignition source, q_b, expressed in kilowatts, shall either be assumed to be constant and equal to the nominal HRR from the burner of 30,0 kW or 20,5 kW, or shall be calculated from the actual consumption of propane gas from Equation (A.4): either

q

(A.3)

_b = 30,0 or 20,5





or

q_b= m_bbh_ceff




(A.4)




where




m_b is the mass flow rate of propane to the burner, expressed in grams per second (g/s);




A/r_ceg- is the effective lower heat combustion of propane, expressed in kilojoules per gram (kJ/g).




Assuming a combustion efficiency of 100 %, Ah_c can be set equal to 46,4 kJ/g.




A.2.2 Heat release from a tested product

The heat release rate of the tested cable shall be taken as the total measured heat release rate minus the heat release rate of the burner. When the burner is ignited the measured heat release rate is not immediately equal to the nominal heat release or value calculated from the mass flow rate of propane (as a result of the transport delay and filling time of the chamber). This leads to negative values of heat release rate of the cable and such negative values shall be set to zero.




The heat release rate from a tested cable q, expressed in kilowatts, is calculated from the equation :




Я ^Е^^х₀₂(ф_{а^Ф_^ Ес_зН^^ь




(A.5)




with <j>, the oxygen depletion factor, given by




^XO₂^{(I X}CO1> W^{1 x}co₂⁾

*o₂^(X~^xc°-i~^x(>i>




(A.6)




and Xq^ , the ambient mole fraction of oxygen, given by


^XCb - ^XO, 0 ^XH₂O )

(A.7)




where

E is the heat release per volume of oxygen consumed, expressed in kilojoules per cubic metre (kJ/m³);

E = 17,2 x 10³ kJ/m³ (25 °С) for the combustion of the tested product;


^ЕСўі% = 16,8 x 10³ kJ/m³ (25 °С) for the combustion of propane;

Й₂₉₈ is the volume flow rate of gas in the exhaust duct at atmospheric pressure and 25 °С

calculated as specified in Equation (A.1);

a is the expansion factor due to the chemical reaction of the air that is depleted of its oxygen (a = 1,105 for combustion of tested product);

*o₂ is the ambient mole fraction of oxygen including water vapour as defined by equation (A.7);

























































































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