Directive 95/28/EC of the European Parliament and of the Council (repealed)Show full title

ANNEX VI U.K. TEST TO DETERMINE THE VERTICAL BURNING RATE OF MATERIALS

1. Principle U.K.

This test consists of exposing samples, held in a vertical position, to a flame and determining the speed of propagation of the flame over the material to be tested.

2. Apparatus U.K.

The apparatus shall consist of:

(a)

a specimen holder;

(b)

a burner;

(c)

a ventilation system to extract gas and combustion products;

(d)

a template;

(e)

marker threads of white mercerized cotton threads having a maximum linear density of 50 tex.

2.1. The specimen holder shall consist of a rectangular frame 560 mm high and shall have two rigidly connected parallel rods spaced 150 mm apart on which pins shall be fitted for mounting the test specimen which is located in a plane at least 20 mm from the frame. The mounting pins shall be not greater than 2 mm in diameter and at least 27 mm long. The pins shall be located on the parallel rods at locations shown in figure 1. The frame shall be fitted onto a suitable support to maintain the rods in a vertical orientation during testing. (For the purpose of locating the specimen on the pins in a plane away from the frame, spacer stubs 2 mm in diameter may be provided adjacent to the pins). U.K.

2.2. The burner is described in figure 3. U.K.

The gas supplied to the burner can be either commercial propane gas or commercial butane gas.

The burner shall be positioned in front of, but below, the specimen such that it lies in a plane passing through the vertical centreline of the specimen and perpendicular to its face (see figure 2), such that the longitudinal axis is inclined upwards at 30 ° to the vertical towards the lower edge of the specimen. The distance between the tip of the burner and the lower edge of the specimen shall be 20 mm.

2.3. The test apparatus may be placed in a fume cupboard assembly provided that the internal volume is at least 20 times, but not more than 110 times, greater than the volume of the test apparatus and provided that no single height, width, or length dimension of the fume cupboard is greater than 2 1/2 times either of the other two dimensions. Before the test, the vertical velocity of the air through the fume cupboard shall be measured 100 mm in front of and behind the final position where the test apparatus will be located. It shall be between 0,10 and 0,30 m/s in order to avoid possible discomfort, by combustion products, to the operator. It is possible to use a fume cupboard with a natural ventilation and an appropriate air velocity. U.K.

2.4. A flat rigid template made of suitable material and of a size corresponding to the size of the specimen shall be used. Holes approximately 2 mm in diameter shall be drilled in the template and positioned so that the distances between the centres of the holes correspond to the distances between the pins on the frames (see figure 1). The holes shall be located equidistant about the vertical centrelines of the template. U.K.

3. Samples U.K.

3.1. The samples dimensions are: 560 x 170 mm. U.K.

3.2. The samples shall be conditioned for at least 24 hours at a temperature of 23 ± 2 °C and a relative humidity of 50 ± 5 % and shall be maintained under these conditions until immediately prior to testing. U.K.

4. Procedure U.K.

4.1. The test shall be carried out in an atmosphere having a temperature between 10° and 30 °C and a relative humidity between 15 % and 80 %. U.K.

4.2. The burner shall be preheated for 2 minutes. The flame height shall be adjusted to 40 ± 2 mm measured as the distance between the top of the burner tube and the tip of the yellow part of the flame when the burner is vertically oriented and the flame is viewed in dim light. U.K.

4.3. The specimen shall be placed on the pins of the test frame, making certain that the pins pass through the points marked off from the template and that the specimen is at least 20 mm removed from the frame. The frame shall be fitted on the support so that the specimen is vertical. U.K.

4.4. The marker threads shall be attached horizontally in front of the specimen at the locations shown in figure 1. At each location, a loop of thread shall be mounted so that the two segments are spaced 1 mm and 5 mm from the plane of the front of the specimen. U.K.

Each loop shall be attached to a suitable timing device. Sufficient tension shall be imposed to the thread to maintain its position relative to the specimen.

4.5. The flame shall be applied to the specimen for 5 seconds. Ignition shall be deemed to have occurred if flaming of the specimen continues for 5 seconds after removal of the igniting flame. If ignition does not occur, the flame shall be applied for 15 seconds to another conditioned specimen. U.K.

4.6. If any result in any set of three specimens exceeds the minimum result by 50 %, another set of three specimens shall be tested for that direction or face. If one or two specimens in any set of three specimens fail to burn to the top marker thread, another set of three specimens shall be tested for that direction or face. U.K.

4.7. The following times, in seconds, shall be measured: U.K.

(a)

from the start of the application of the igniting flame to the severance of the first marker thread (t1);

(b)

from the start of the application of the igniting flame to the severance of the second marker thread (ts);

(c)

from the start of the application of the igniting flame to the severance of the third marker thread (t3).

5. Results U.K.

The observed phenomena shall be written down in the test-report, to include:

• the durations of combustion: ₁, t₂ and t₃ in seconds,

• the corresponding burnt distances: d₁, d₂ and d₃ in mm.

The burning rate V₁ and the rates V₂ and V₃, if applicable, shall be calculated (for each sample if the flame reaches at least the first marker thread) as follows:

The highest burning rate of V₁, V₂ and V₃ shall be taken into account.

Specimen holder

(Dimensions in millimetres)

Burner ignition location

Gas burner

(Dimensions in millimetres)