Comparison of fire resistance test of high flame retardant metal composite plate shaft furnace

Abstract: This article mainly analyzes and compares the testing differences between Russian GOST30244-94 (Test Method II) and Chinese GB/T8625-2005. It elaborates on the experimental process of using Russian GOST30244-94 standard for fire resistance testing of high flame retardant metal composite panels, in order to provide reference for the selection and application of GOST30244-94 standard fire resistance testing and high-rise building fire curtain wall materials.

Keywords: GOST 30244-94; GB/T8625-2005； High flame retardant core material; Fireproof metal composite board; Vertical furnace fire test; Differential comparison

Currently, countries around the world have increasingly strict requirements for building safety, and fire resistance is one of the most important indicators of safety. However, due to the different methods and standards for testing the combustion performance of building materials in various countries, export products must try their best to meet the local government's flame retardant technical specifications for metal composite materials in order to meet the relevant needs in international trade. At present, there is no testing organization in Chinese Mainland that can conduct fire test according to the Russian GOST 30244-94 standard, so the fire test according to the GOST 30244-94 standard needs to be carried out and samples need to be sent to the Russian National Laboratory in Moscow for testing, which not only has a long cycle but also costs a lot of money. When most of them are sent for testing, they first use the GB/T8625-2005 building materials fire resistance test method in China, and then send samples to the Russian National Laboratory in Moscow for testing after the test results are acceptable, but the test results of the two tests are often very different. In order to gain a deeper understanding of the testing methods and criteria for the Russian GOST30244-94 standard, we used KEOCT's specialized formula to produce high flame retardant fire-resistant metal composite panels. Samples were sent to Moscow for testing in accordance with the Russian GOST30244-94 standard, and an analysis and comparison were conducted between the Russian GOST30244-94 and the national standard GB/T8625-2005, in order to provide reference and guidance for relevant parties.

1、 Analysis of the Differences between the Russian GOST30244-94 Flammability Test for Building Materials (Method II) and the GB/T8625-2005 Refractory Test Method for Building Materials

1. Preparation of experimental samples

1.1.    GOST 30244-94 Test Samples:

Test 4 samples per set and test 3 sets of data. 12 samples with a length of 1000mm and a width of 190mm need to be prepared, and the thickness of the samples should meet the thickness of the materials used under actual conditions. If the thickness of the material exceeds 700mm, the thickness of the sample should be 70mm; The surface exposed during sample preparation does not need to be processed.

1.2. GB/T8625-2005 Test Samples

The specifications and description of test samples in GB/T8625-2005 require the following number of specimens: each test shall consist of 4 specimens as a group, each of which shall be made according to the actual thickness of the material used. The surface specification is 1000mm × 190mm. When the actual thickness of the material exceeds 80mm, the thickness of the sample should be taken as (85 ± 5) mm. Three sets of specimens are made for isotropic materials, and four sets of specimens are made for thin films, fabrics, and non-isotropic materials. Each two sets of specimens should be sampled and made from the longitudinal and transverse directions of the material. For asymmetric materials, two sets of specimens should be made on each side of the specimen. If only one side is required to classify the combustion performance level, three sets of specimens can be made on that side.

Preparation conditions for specimens: Prior to testing, the specimens must be adjusted to a constant mass at a temperature of (23 ± 2) ℃ and a relative humidity of (50 ± 5)%. The judgment condition is that the interval is 24 hours, and the mass change rate of the two weighings before and after is not greater than 0.1%. If the equilibrium state cannot be determined by weighing, it should be stored for 28 days under the above temperature and humidity conditions before the experiment.

From the above, it can be seen that the length and width dimensions of the test samples in GB/T8625-2005 are consistent with GOST 30244-94, except for differences in the thickness dimension requirements for ultra thick plates.

2. Vertical furnace fire testing device

2.1. GOST30244-94 (Method II) Testing device: see Figure 1 below

1. Combustion chamber; 2. Sample holder; 3. Sample; 4. Gas burner; 5. Air supply ventilation equipment; 6. Combustion chamber door; 7. Partition board; 8. Ventilation duct; 9. Gas pipeline; 10. 11. Thermocouple; 12 Ventilation hood

2.2 GB/T 8625-2005 Testing Device: See Figure 2 below

1. Air inlet pipe; 2. Air stabilizer; 3. Wire mesh; 4 burners; 5. Test piece; 6. Wall temperature thermocouple; 7. Furnace wall structure; 8. Flue thermocouple; 9. T-shaped pressure measuring tube.
From the above two figures, it can be seen that the experimental setup and dimensions of the two experimental methods are very similar.

3. Test calibration and gas

3.1 GB/T8625-2005 Combustion Gas and Flow Rate for Burners

The combustion gas used in GB/T8625-2005 burners is a mixture of methane and air: the methane flow rate is 35 ± 0.5L/min, and its purity is greater than 95%; The air flow rate is 17.5 ± 0.2L/min.

3.2 GOST30244-94 (Method II) Burner Use Gas and Calibration
GOST30244-94 (Method II) The burner uses a mixture of gas and air, and calibration should be carried out according to Table 1 before the test to determine the gas consumption (liters/minute).

The specific experimental calibration methods are shown in Table 1

Table 1 Test Calibration

From Table 1 above, it can be seen that GB/T8625-2005 and GOST30244-94 (Method II) use different gases for the burner. At the same time, GB/T8625-2005 specifies the flow rate of gas, while GOST30244-94 (Method II) does not specify the flow rate of gas, but uses Table 1 for calibration, indicating that there is a significant difference in gas flow rate between the two, which means a difference in flame size and will have a significant impact on the detection results.

4. Experimental operation

4.1 GB/T8625-2005 Test Operation

① Fix four specimens that have been adjusted to meet the specified requirements vertically on the specimen support to form a vertical square flue, with a relative distance of 250mm between the specimens;

② Maintain the pressure level inside the furnace at -15 ± 10Pa;

③ Before placing the test piece into the combustion chamber, the temperature of the furnace wall should be preheated to 50 ℃;

④ Place the specimen in the designated position inside the combustion chamber and close the furnace door;

⑤ When the furnace wall temperature drops to 40 ℃, start the timing test while igniting the burner. During the experiment, an air flow rate of 10 ± 1m ³/min and a temperature of 23 ± 2 ℃ should be maintained inside the vertical furnace. The combustion gas used for the burner is a mixture of methane and air: the methane flow rate is 35 ± 0.5L/min, and its purity is greater than 95%; The air flow rate is 17.5 ± 0.2L/min.

4.2. GOST 30244-94 Test Procedure (Method II)

① Check the flue gas temperature measurement system when the combustion chamber door and ignition source are not working, and open the measuring instrument and inflate it accordingly;

② Weigh the 4 samples and place them on a bracket, then place them into the combustion chamber;

③ Open the measuring instrument, inflation and exhaust device, ignition source, and close the combustion chamber door;

④ The duration of the impact on flame samples from ignition sources should be 10 minutes; Turn off the ignition source in 10 minutes. Record the duration of independent combustion (smoldering) when there are signs of flame or smoldering. The test is considered complete after the sample has cooled to ambient temperature.

⑤ After the experiment is completed, turn off the inflation device, exhaust device, and measuring instrument, and remove the sample from the combustion chamber;

⑥ For each experiment, determine the following indices: temperature of the flue gas, duration of independent combustion and/or smoldering, length of sample damage, and mass of the sample before and after the experiment;

⑦ Record the temperature of the flue gas during the experiment, and record at least two readings per minute based on the four thermocouples installed in the air duct. Also, record the duration of independent combustion of the sample (in the presence of flames or smoldering characteristics).

⑧ During the experiment, the following observation data should also be recorded:

The time when the smoke reaches its maximum temperature, the flame exceeding the sample end face and non heated surface, the sample burning through, and the formation of hot melt products. The appearance of the sample after the experiment includes smoke black precipitation, color change, melting, sintering, shrinkage, expansion, bending, crack formation, etc.

5. Experimental results and judgment

5.1 GB/T8625-2005 Experimental Results and Judgment

a) The average remaining length of the 150mm specimen after combustion is ≥, and there is no specimen with zero remaining length after combustion; (Changes such as discoloration, blackening by smoke, bending, wrinkling, bubbling, melting, burning, dripping, and falling off of the specimen during the test are not considered as a basis for determining combustion. If the dripping and falling objects continue to burn at the bottom of the sieve for more than 20 seconds, they should be noted in the experimental report.)

b) The average flue gas temperature measured by 5 thermocouples for each set of specimens shall not exceed 200 ℃.

c) Materials that pass the combustion vertical furnace test and meet the requirements of GB 8624 for flammability test (GB/T 8626) and smoke density test (GB/T 8627) can be classified as non combustible building materials.

5.2 GOST 30244-94 (Method II) Experimental Results and Judgment

According to GOST 30244-94 (Method II), combustible building materials are classified into four levels of combustibility: Г 1, Г 2, Г 3, and Г 4. The corresponding fire protection parameter indicators for each level are shown in Table 2.

Note: The part of the sample that has not burned or burnt on the surface or inside is considered undamaged. Smoke black precipitation, changes in sample color, local gaps, sintering, melting, expansion, contraction, bending, changes in sample style, and surface roughness cannot be considered as damage.

From this, it can be seen that the qualification of the GB/T8625-2005 combustion shaft furnace test does not mean that it can pass the GOST 30244-94 (Method II) Г 1 level. It may be a Г 1 or Г 2 level, indicating that the GOST 30244-94 (Method II) Г 1 level test indicators have higher requirements than the GB/T8625-2005 combustion shaft furnace test.

2、 High flame retardant fire-resistant metal composite panel - GOST30244-94 standard fire test in Russia (Test Method II)

1. Preparation of test samples: 12 HFR MCP samples with a length of 1000mm, a width of 190mm, and a thickness of 4mm, using KEOCT HFR high flame retardant core material as the core material.
2. Sample installation

3. The condition of the test sample after the experiment: see Figure 4

 

4. Test results and judgments: see Table 3

Table 3 Determination of GOST30244 test results

3、 Conclusion

By comparing and analyzing the GB/T 8625-2005 and GOST30244-94 standards, and conducting GOST30244-94 fire performance tests on fire-resistant metal composite panels with high flame retardant core materials, we have drawn the following conclusions:

1) According to GB/T8625-2005 and GOST 30244-94 tests, the appearance dimensions of the detection device are basically the same; The length and width dimensions of the test samples are basically the same, except for differences in the thickness specifications of the ultra thick plate.

2) GB/T8625-2005 and GOST30244-94 (Method II) use different gases for the burner, and GB/T8625-2005 specifies the flow rate of gas. GOST30244-94 (Method II) does not specify the flow rate of gas, but uses Table 3 for calibration, indicating that there is a difference in gas flow rate between the two, which means that the difference in flame size will also have a significant impact on the detection results.

3) The qualification of the GB/T8625-2005 combustion shaft furnace test does not mean that it can pass the GOST 30244-94 (Method II) Г 1 level. It may be a Г 1 or Г 2 level, indicating that the GOST 30244-94 (Method II) Г 1 level test indicators have higher requirements than the GB/T8625-2005 combustion shaft furnace test indicators.

4) The HFR MCP produced using our company's KEOCT HFR high flame retardant special formula core material can completely pass the GOST 30244-94 (Method II) Г 1 level testing in Russia.

Reference

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2) WANG X H, ZHAO C G. Flame retardant fire security testing and materials application research for ACP[J].  China Plats Ind,2012(1):55-60.