GB/T 25353-2010 Combustion and flame spread characteristics of thermal and sound insulation materials
1 scope
This standard specifies test methods for the flammability and flame spread characteristics of thermal and sound insulation materials exposed to radiant heat sources and flames.
This standard is suitable for evaluating the flammability and flame spread characteristics of thermal and sound insulation materials.
2 language and definition
The following terms and definitions apply to this standard.
2.1
flame propagation flame propagation
The furthest distance that the flame can be seen to spread along the length of the specimen.
Note: Measurement starts from the center point of the combustion source flame. This distance is measured after initial ignition but before all flames on the specimen have extinguished, as opposed to measuring the char length after the test.
2.2
Thermal/acoustic insulation material
A material or material system that blocks heat and/or sound.
Examples: Foam and film-coated fiberglass or other flocculent materials.
2.3
zero point zero point
The contact point between the burner flame and the sample.
3 Trial preparation
3.1 Radiation panel test chamber
The radiation panel test chamber is shown in Figure 1. The radiation panel test box should be a closed device with a length of (1 397 ± 3) mm, a width of (495 ± 3) mm, and a height of 710 mm to 762 mm above the specimen. The side walls, bottom and top should be insulated with fibrous ceramic insulation panels. On the front panel, there should be an unventilated, high-temperature-resistant glass window for observing the specimen during the test. A door is provided under the window for access to the movable specimen platform. The bottom of the test chamber shall be a sliding steel platform that ensures that the specimen holder is in a fixed and level position. The end of the test chamber opposite to the radiant heat source should have a built-in chimney. Its external dimensions are length (423±3) mm, width (139±3) mm, and height (330±3) mm. The internal dimensions should be length (395). ±3) mm, width (114±3) mm. The chimney should extend to the top of the test chamber (see Figure 2).
3.2 Radiant heat source
3.2.1 Radiant heat sources are divided into electric heating panels and propane gas panels, which should be installed in a frame made of cast iron or equivalent material. The electric heating plate should have six radiating strips 76 mm wide, and the radiating strips should be perpendicular to the long side of the electric heating plate. The electric heating plate should have a radiating surface with a length of (470±3) mm and a width of (327±3) mm (see Figure 3), and can withstand a temperature of 704°C. The propane gas panel should be made of refractory porous material, have a radiating surface of length (457±3) mm and width (305±3) mm (see Figure 4), and be able to withstand a temperature of 816°C.
3.2.2 The power supply of the electric heating plate should be three-phase, and the operating voltage should be 208 V. A single-phase 240 V electric heating plate can also be used. Solid-state power controllers and microprocessor-based controllers should be used to set operating parameters for hot plates.
3.2.3 Propane gas panels use propane (liquefied gas) as fuel. The fuel system shall consist of a Venturi-type air mixer for mixing propane gas and air at approximately one atmosphere. To monitor and control the flow of fuel and air to the gas plate, appropriate instrumentation should be provided, including a gas flow meter, an air flow regulator, and a barometer.
3.2.4 The radiant panel should be placed at a position (191±3) mm above the zero point of the sample in the test chamber, at an angle of 30° to the horizontal plane of the sample.
3.3 Trial support system
3.3.1 A sliding platform should be used as a specimen placement frame (see Figure 5). The bracket can be fixed to the upper surface of the table with bolts to facilitate the installation of specimens of different thicknesses. Place the specimen on a high-temperature resistant insulating plate against the bottom of a sliding platform or the base of a stand. In order to meet the height requirements of the specimen, multi-layer insulation boards can be selected according to the thickness of the specimen. However, a sliding platform deeper than the 51 mm shown in Figure 5 can also be used as long as the height requirements of the specimen can be met.
3.3.2 A ceramic heat insulation board or other high-temperature-resistant material with a length of 1054mm, a width of 210mm, and a thickness of 13mm should be attached to the back of the platform to insulate and prevent The specimen was overheated. The height of this plate should not impede movement of the sliding platform (in and out of the test chamber). If the back of the platform is machined high enough to prevent excessive preheating of the specimen when the sliding platform is removed, no heat shield is required.
3.3.3 Place the specimen horizontally on the heat shield, and place a fixed frame made of mild steel on the specimen. The thickness of the steel is 3.2 mm, the overall dimensions of the fixed frame are (584±3) mm long and (333±3) mm wide, with a sample opening in the middle (483±3) mm long and (273±3) mm wide (see Figure 6) . The front, rear and right edges of the upper edge of the frame should be against the top of the sliding platform, the lower edge should clamp the four sides of the specimen, and the right side of the lower edge should be aligned with the sliding platform.
3.4 Burner
The burner shall be an axially symmetrical Venturi ignition device with a propane supply pipe having a bore diameter of 0.15 mm. The length of the combustion tube should be 71 mm. By adjusting the propane gas flow, a 19 mm blue inner flame is produced in the center of the flame. An indicator device (such as a thin metal strip) with a length of 19 mm should be welded to the top of the burner to help set the flame length. The total flame length should be 127 mm. There should be means to move the burner from the ignition position to ensure that the flame is horizontal and at least 51 mm above the plane of the specimen (see Figure 7).
3.5 Hot electric couple
A small hole should be drilled in the back panel of the box to insert the thermocouple that monitors the temperature inside the box. The thermocouple should be 279 mm from the back wall of the box, 292 mm from the right side of the box wall, and 51 mm below the radiant panel. The thermocouple shall be type K (nickel-chromium-nickel aluminum) with a wire diameter of 0.511 mm [AWG No. 24].
3.6 heat flow calculation
The heat flow meter should be a 25.4 mm cylindrical water-cooled, total heat flux density type, foil-type Gardon heat flow meter with a measuring range of (0~5.7) W/cm2.
3.7 Heat flow meter calibration specifications and procedures
3.7.1 The specifications of the heat flow meter are as follows:
——The diameter of the metal foil should be (6.35±0.13) mm;
——The thickness of metal foil should be (0.013 0±0.002 5) mm;
——The metal foil material should be thermocouple grade constantan;
——Temperature measurement should be copper-constantan thermocouple;
——The diameter of the copper center wire should be 0.013 mm;
——The entire detection surface should be coated with a thin layer of "black velvet" paint with an emissivity of 96% or greater.
3.7.2 The calibration requirements for heat flow meters are as follows:
——Calibration method applies standard sensor for calibration;
——Standard sensors should comply with the provisions of 3.6;
——The benchmark of standard sensors should be traceable to national standards or equivalent international standards;
——The method of transferring heat should be to use graphite plate as the medium;
——The graphite plate should be electrically heated, and it should have a clean surface area with a length and width of at least 51 mm on both sides; its thickness is (3.2±1.6) mm;
——Place the two sensors opposite each other at the center point of the graphite plate and maintain an equal distance from the graphite plate;
——The distance between the heat flow meter and the graphite plate should be within the range of 1.6 mm to 9.5 mm;
——The range used for calibration should be at least (0~3.9) W/cm2, and not greater than (0~6.4 )W/cm2;
——The recording device used should be able to record two sensors at the same time or at least within 0.1 s.
3.8 Heat flow meter bracket
The bracket of the heat flow meter should be made of a steel plate with a thickness of 3.2 mm, with dimensions of (333±3) mm long (from front to back) and (203±3) mm wide, and should rest on the top of the sliding platform. The bracket has an opening capable of receiving a 12.7 mm thick refractory board sheet, which opening should be flush with the top of the sliding platform. The heat flow meter holder shall have three 25.4 mm diameter heat flow meter sockets extending through the support plate. The distance from the center of the first jack ("zero" point) to the surface of the radiating panel should be (191±3) mm; the distance between the centers of two adjacent jacks should be 51 mm (see Figure 8).
3.9 Table
Measure and record the output values of heat flow meters and thermocouples using a calibrated recording device or computer data acquisition system with a range that meets the needs. During calibration, the data acquisition system should record the heat flow meter output at least once every second.
3.10 Accounting device
The timing device for measuring the burner flame action time is a stopwatch or other device, and its accuracy should be ±1 s/h.
4 Trial test
4.1 trial system
At least three specimens shall be prepared and tested. If anisotropic film cladding materials are used, tests shall be carried out in both the warp and weft directions.
4.2 Composition
The test specimen should include all materials used in the barrier structure (including fibers, films, fabrics, tapes, etc.). Heat sealing is a better method for preparing fiberglass specimens. Covering materials that cannot be heat sealed can be stapled, sewn or pasted. They should be fixed along the long side of the seam and be as continuous as possible. The thickness of the specimen shall be consistent with the thickness of the material installed on the aircraft.
4.3 Trial length
Non-rigid core materials, such as fiberglass fabrics, should be cut to a length of (584±6) mm and a width of (318±6) mm; rigid materials, such as foam, should be cut to a length of (584±6) mm and a width of (292 ±6) mm so that it can fit completely into the sliding platform frame and its exposed surface is flush with the frame opening.
5 Sample pretreatment
Before the test, the sample should be placed in an environment with a temperature of (21±2)°C and a relative humidity of (55±10)% for at least 24 hours.
6 Equipment School Associate
6.1 Pull the platform out of the test chamber and install the heat flow meter bracket (see Figure 8). Insert the heat flow meter into the first hole (the "zero" position) and push the platform back into the chamber. The distance from the center of the heat flow meter to the surface of the radiant panel should be (191±3) mm. Before heating with the electric hot plate, ensure that the surface of the heat flow meter is clean and that cooling water flows through the heat flow meter.
6.2 If a propane gas panel is used, after igniting the gas, the gas and air mixture should be adjusted to reach (1.700±0.085) W/cm< in the "zero" position. /span> in the "zero" position. Allow the unit to reach a steady state, at which point the burner should be off and in the down position. 2. If a hot plate is used, the power controller should be set to achieve (1.700±0.085) W/cm2
6.3 After reaching a steady state, move the heat flow meter 51 mm from the "zero" position (first hole) to the 1 position, and record the heat flow. Then move the heat flow meter to position 2 and record the heat flow. The value of the heat flow meter should be stabilized at each position. Table 1 gives typical calibration values for the three positions.
6.4 Open the door and remove the heat flow meter and its bracket.
7 Trial introduction
7.1 Light the burner ensuring it is at least 51 mm above the top of the platform. The burner shall not be placed in the test position until the start of the test.
7.2 Place the specimen in the frame of the sliding platform, ensuring that the surface of the specimen is flush with the top of the platform. At the "zero" position, the sample surface should be (191±3) mm below the radiant plate.
7.3 Place a fixed frame above the specimen. At the "zero" position, the distance between the sample and the radiant plate should be (191±3) mm. Since the film and fiberglass are combined together, a small opening should be cut in the film covering to remove the air inside. The incision should be longitudinal, 51 mm in length, and located (76 ± 13) mm from the midpoint of the left side of the fixed frame.
7.4 Immediately push the sliding platform into the test chamber and close the bottom door.
7.5 Put the burner in the test position and start the timer at the same time. The angle between the burner and the specimen should be 27° and located approximately 1 mm above the specimen (see Figure 8). The burner flame should contact the center of the specimen at the "zero" position. The stop device shown in Figure 9 allows the operator to accurately position the burner for each test.
7.6 The test is carried out for 15 s, and then the burner is moved to a position of at least 51 mm above the specimen.
8 Report
8.1 Describe the specimen in detail.
8.2 Report any changes in the specimen, such as shrinkage, melting, etc.
8.3 Reports flame spread distance. If this distance is less than 51 mm, it is reported as passing (no measurement required).
8.4 Report the flame burning time.
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