GB/T 8626-2007Test method of flammability for building materials (English PDF)

3.3 of the 2007 Edition);

--- Add the term "multi-layered product" (see 3.4 of this Edition);

--- Delete the provision to seal the air gap between the two supports on the front of the

chamber (see 4.2 of the 2007 Edition);

--- Add the provision that the airflow velocity in the chamber flue be measured along the

central axis of the flue (see 4.2 of this Edition);

--- Add provision for specimen frames for testing multi-layered products with a thickness

greater than 10 mm (see 4.5 and Figure 4 of this Edition);

--- Add provision for the mounting and fixing of loose materials (see 4.5 and Figure 5 of

this Edition);

--- Change the accuracy for the timer (see 4.7 of this Edition; 4.7 of the 2007 Edition);

--- Delete the provisions for a specimen template with length of 250 0 -1 mm, and wight of 180

-1 mm (see 4.8 of the 2007 Edition);

--- Add provision for the flame height measurement method (see 4.9.1 of this Edition);

--- Add the provision that the anemometer be of the thermal type (see 4.10 of this Edition);

--- Change the mass per unit area of the filter paper (see 4.11 of this Edition; 4.11 of the

4.12 of this Edition);

--- Change the specimen dimensions (see 5.2 of this Edition; 5.2 of the 2007 Edition);

--- Add provision regarding the number of tests for products with asymmetrical thickness

where either surface might be exposed to fire in actual application (see 5.4.2 of this

Test Method of Flammability for Building Materials

WARNING.

Toxic or harmful fumes may be generated during the combustion test, and hazards may

arise during the testing of specimens and the disposal of test residues.

Laboratory management and operating personnel are responsible for assessing all

potential hazards to human health, establishing safety safeguards, formulating safety

guidelines, training relevant personnel, and ensuring that laboratory staff consistently

adhere to these safety guidelines.

Equipping the facility with appropriate fire-extinguishing apparatus is essential.

For certain smoldering specimens that are difficult to extinguish completely, immersing

the specimen in water may prove effective.

5907.2 and GB 8624 and the following apply.

3.1 Product

Materials, parts, or components for which relevant information is required.

3.2 Essentially flat product

A product exhibiting one of the following characteristics.

a) A flat fire-exposed surface.

b) If the product surface is irregular but exhibits this irregularity uniformly across the entire

fire-exposed surface, it is considered a flat fire-exposed surface provided it meets one of

the following conditions.

1) Within a representative surface area of 250 mm × 250 mm, at least 50% of the surface

is located at a perpendicular distance of no more than 6 mm from the plane defined

by the highest point of the fire-exposed surface;

2) For surfaces containing gaps, cracks, or holes, the width of such gaps, cracks, or

holes does not exceed 6.5 mm, the depth does not exceed 10 mm, and their total

surface area does not exceed 30% of the 250 mm × 250 mm representative area of

the fire-exposed surface.

3.3 Flaming droplet/particle

During the flaming test, material that separates from the specimen and ignites the filter paper

placed beneath it.

3.4 Multi-layered product

A product composed of two or more layers of different materials.

NOTE. Multi-layered products contain primary components and/or secondary components.

3.5 Sustained flaming

The flames last longer than 3 s.

3.6 Ignition

The phenomenon with a sustained flame occurs.

4.1 Laboratory

The ambient temperature of the laboratory shall be (23 ± 5) °C, and the relative humidity shall

be (50 ± 20) %.

NOTE. A dimly lit laboratory facilitates the detection of small flames on the specimen surface.

4.2 Combustion chamber

The combustion chamber shall be constructed of stainless-steel sheet and fitted with a heat-

resistant glass door to allow for test operations and observation from at least the front and one

side of the chamber, see Figures 1a) and 1b). Natural ventilation of the combustion chamber

shall be provided via a square grid at the bottom of the chamber, see Figure 1c). The square

grid shall be made of stainless steel with a thickness of 1.5 mm, a height of 50 mm, and a mesh

opening size of 25 mm × 25 mm, see Figure 1d). The chamber shall be placed on supports 40

mm in height to create an air gap beneath the chamber for natural ventilation. The combustion

chamber shall be positioned beneath a suitable exhaust hood; with only the burner ignited and

the exhaust hood operating, the air velocity along the central axis of the chamber's flue shall be

(0.7 ± 0.1) m/s.

7.2.1 Verify that the air flow velocity within the combustion chamber flue meets the

requirements (see 4.2).

7.2.2 Remove the 6 specimens and filter papers from the conditioning environment and

complete the test within 30 min. If necessary, the specimens can be placed in a sealed container

for transfer from the conditioning room to the test apparatus.

7.2.3 Clamp the specimen in the specimen holder such that the two side edges and the top edge

are enclosed by the holder, and the bottom edge is positioned 30 mm above the bottom of the

holder (see Figures 3 ~ 6).

NOTE. Marking the specimen holder helps ensure the bottom edge of the specimen is correctly

positioned.

7.2.4 Adjust the burner angle to 45° and verify the distance between the burner and the

specimen using the positioning gauge specified in 4.9.2 or 4.9.3 (see Figures 7 and 8).

7.2.5 Place two sheets of filter paper in the aluminum foil collection tray beneath the specimen

within 3 min prior to the test.

7.3 Test procedure

7.3.1 Ignite the burner (positioned vertically) and allow the flame to stabilize. Adjust the

burner's fine-tuning valve and measure the flame height using the measuring tool specified in

4.9.1; the flame height shall be 20 mm. Perform the measurement away from the burner's preset

position to avoid accidental ignition of the specimen. Measure the flame height before each

ignition.

NOTE. A dimly lit environment facilitates flame height measurement.

7.3.2 Tilt the burner 45° along its vertical axis and advance it horizontally until the flame

reaches the preset contact point on the specimen.

Start the timer upon contact between the flame and the specimen; apply the flame for 15 s or

7.3.3 Ignition method

The test shall be conducted using surface ignition, edge ignition, or both methods.

7.3.3.1 Surface ignition

For essentially flat product, the flame shall be applied to the centerline of the specimen, 40 mm

above the bottom edge (see Figure 11). Separate tests shall be conducted for different surfaces

likely to be exposed to fire in actual application (see 5.4.2).

7.3.3.2 Edge ignition

7.3.3.2.1 For single-layered or multi-layered essentially flat product with a total thickness not

exceeding 3 mm, the flame shall be applied to the center point of the specimen's bottom edge

[see Figure 8a)].

Products whose edges are not exposed to fire in actual application should not be subjected to

edge ignition tests.

NOTE. The flame width is approximately 5 mm, covering the entire thickness of the specimen.

7.3.3.2.2 For single-layered or multi-layered essentially flat product with a total thickness

exceeding 3 mm, the flame shall be applied to the centerline of the long edge of the specimen's

bottom surface, at a distance of 1.5 mm from the face exposed to fire (see Figure 8b).

7.3.3.2.3 For all multi-layered products with a total thickness exceeding 10 mm, an additional

test shall be performed by rotating the specimen 90° along its vertical axis and applying the

flame to the specimen edge at the centerline of the bottom edge of each material layer of

material (see Figure 8c). Testing is not required for an external layer if it consists of a single

layer or multiple adjacent thin layers with a thickness or combined thickness of less than 1 mm.

Testing is required if the thickness or combined thickness is no less than 1 mm. Internal layers

of the product, such as adhesive layers, shall be tested. If the product contains two or more

identical material layers, testing is required for only one of them.

Two tests shall be conducted at each flame application point to identify the point yielding the

worst test result. A complete set of tests on 6 specimens shall then be performed at the point

identified as yielding the worst result.

7.3.4 For products that are non-essentially flat and for products tested under actual application

conditions, ignition shall be carried out in accordance with 7.3.3.1 and 7.3.3.2.The method of

fixing the specimen shall be described in detail in the test report.

Two tests shall be performed at each point of flame application to identify the point yielding

the worst test result. A full set of tests on 6 specimens shall then be conducted at the point of

flame application that yielded the worst result.

To reflect actual application conditions, the specimen may be fixed using the specimen holder

specified in 4.5 or a specially designed frame.

7.4 Test duration

7.4.1 For an ignition time of 15 s, the total test duration is 20 s, measured from the start of

ignition.

7.4.2 For an ignition time of 30 s, the total test duration is 60 s, measured from the start of

ignition.

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