UL94 塑料的燃烧级别

Test for Flammability of Plastic Materials for Parts in Devices and Appliances

TESTS

7 Horizontal Burning Test; HB

(ASTM D 635, D 4804, IEC 707, or ISO 1210)

7.1 Test criteria

7.1.1 A material shall be classified HB when tested as described in 7.2.1 – 7.5.10.

7.1.2 A material classed HB shall (also see 7.1.4):

a) Not have a burning rate exceeding 40 mm per minute over a 75 mm span for specimens having a thickness of 3.0 – 13 mm, or

b) Not have a burning rate exceeding 75 mm per minute over a 75 mm for specimens having a thickness less than 3.0 mm, or

c) Cease to burn before the 100 mm reference mark. See 7.5.1 and 7.5.9.

*7.1.2 revised July 29, 1997*

7.1.3 A material classified HB in the 3.0 +0.2 mm thickness shall automatically be classed HB down to a 1.5

mm minimum thickness without additional testing. *7.1.3 revised July 29, 1997*

7.1.4 If only one specimen from a set of three specimens does not comply with the requirements, another set of three specimens is to be tested. All specimens from this second set shall comply with the requirements in order for the material in that thickness to be classified HB.

*7.1.4 revised July 29, 1997*

7.2 Test apparatus

7.2.1 See 5.1, 5.2, 5.5 – 5.12, 5.20 and 5.21.

7.3 Test specimens

7.3.1 All specimens shall be cut from sheet material, or shall be cast or injection, compression transfer or pultrusion molded to the necessary form. After any cutting operation, care is to be taken to remove all dust and any particles from the surface; cut edges are to have a smooth finish. Fabrication of test specimens shall be in accordance with current ASTM Practices.

7.3.2 Standard bar specimens are to be 125 ±5 mm long by 13.0 ±0.5 mm wide, and provided in the minimum thickness and 3.0 (-0.0 +0.2) mm thick. The 3.0 mm thick specimens are not necessary if the minimum thickness is greater than 3.0 mm, or the maximum thickness is less than 3.0 mm. The maximum thickness is not to exceed 13 mm. The maximum width is not to exceed 13.5 mm, the edges are to be smooth, and the radius on the corners is not to exceed 1.3 mm.

7.3.3 Material Ranges – If a material is to be considered in a range of colors, densities, melt flows, or reinforcement, specimens representing these ranges are also to be provided.

7.3.4 Specimens in the natural and in the most heavily pigmented light and dark colors are to be provided and considered representative of the color range, if the test results are essentially the same. In addition, a set of specimens is to be provided in the heaviest organic pigment loading, unless the most heavily pigmented light and dark colors include the highest organic pigment level. When certain color pigments (for example, red, yellow, or the like) are known to affect flammability characteristics, they are also to be provided.

7.3.4 revised June 10, 1997

7.3.5 Specimens in the extremes of the densities, melt flows and reinforcement contents are to be provided and considered representative of the range, if the test results are essentially the same. If the burning characteristics are not essentially the same for all specimens representing the range, evaluation is to be limited only to the materials in the densities, melt flows, and reinforcement contents tested, or additional specimens in intermediate densities, melt flows, and reinforcement contents are to be provided for tests.

7.4 Conditioning

7.4.1 Two sets of three specimens are to be preconditioned as in 6.1.

7.5 Procedure

7.5.1 Three specimens are to be tested. Each specimen is to be marked with two lines perpendicular to the longitudinal axis of the bar, 25 ±1 mm and 100 ±1 mm from the end that is to be ignited.

7.5.1 revised April 30, 1997

7.5.2 Clamp the specimen at the end farthest from the 25 mm mark, with its longitudinal axis horizontal and its transverse axis inclined at 45 ±2 degrees. The wire gauze is to be clamped horizontally beneath the specimen, with a distance of 10 ±1 mm between the lowest edge of the specimen and the gauze with the free end of the specimen even with the edge of the gauze. See Figure 7.1.

7.5.2 revised April 30, 1997

7.5.3 The methane gas supply to the burner shall be arranged as in Figure 7.3 and adjusted to produce a gas flow rate of 105 ml/min with a back pressure less than 10 mm water. See ASTM D 5207.

7.5.4 The burner is to be placed remote from the specimen and ignited. Adjust the burner to produce a blue flame 20 ±1 mm high. The flame is to be obtained by adjusting the gas supply and the air ports of the burner until an approximate 20 ±1 mm yellow-tipped blue flame is produced. Increase the air supply until the yellow tip disappears. Measure the height of the flame again and adjust it if necessary.

7.5.5 The test flame shall be calibrated in accordance with ASTM D 5207 at least once a month and when the

gas supply is changed, test equipment is replaced, or when data is questioned. *7.5.5 revised July 10, 1998*

7.5.6 If the specimen sags at its free end during the initial set up, the support fixture illustrated in Figure 7.2 is to be positioned under the specimen with the small extending portion of the support fixture at least 20 mm from the free end of the specimen. Enough clearance is to be provided at the clamped end of the specimen so that the support fixture is capable of being freely moved sidewards. As the combustion front progresses along the specimen, the support fixture is to be withdrawn at the same approximate rate.

7.5.6 revised June 10, 1997

7.5.7 Apply the flame to the free end at the lower edge of the specimen. The central axis of the burner tube is to be in the same vertical plane as the longitudinal bottom edge of the specimen and inclined toward the end of the specimen at an angle of approximately 45 degrees to the horizontal. See Figure 7.1.

7.5.8 Position the burner so that the flame impinges on the free end of the specimen to a depth of 6 ±1 mm. Apply the test flame for 30 ±1 seconds without changing its position; remove the burner after 30 ±1 seconds, or as soon as the combustion front of the specimen reaches the 25 mm mark (if less than 30 seconds). Start the timing device when the combustion front reaches the 25 mm mark.

7.5.9 If the specimen continues to burn after removal of the test flame, record the time in seconds, for the combustion front to travel from the 25 mm mark up to the 100 mm mark and record the damaged length, L. If the combustion front passes the 25 mm mark but does not pass the 100 mm mark, record the elapsed time in seconds and the damaged length, L, in millimeters between the 25 mm mark and where the combustion front stops.

7.5.10 The test procedure is to be conducted on at least three specimens.

7.6 Calculations

7.6.1 Calculate the linear burning rate, V, in millimeters per minute, for each specimen using the equation: V = 60 L/t

in which: V is the linear burning rate in mm/minute L is the damaged length, in millimeters t is time, in seconds

Note: If the flame front passed the 100 mm mark, L = 75 mm.

7.7 Results

7.7.1 The following are to be recorded for each specimen: a) Whether or not the flame front passed the 25 mm and 100 mm marks. b) If the flame front passed the 25 mm mark but ceased before the 100 mm mark, the damaged

length, L and elapsed time, t.

c) If the flame front passed the 100 mm mark, the elapsed time t between the 25 mm and 100 mmmarks.d) The calculated linear burning rate.

Figure 7.1
Horizontal burning test for HB classification
Figure 7.2
Flexible specimen support fixture

8 20 mm Vertical Burning Test; V-0, V-1, or V-2

(ASTM D 3801, IEC 707, or ISO 1210)

8.1 Test Criteria

8.1.1 Materials shall be classified V-0, V-1, or V-2 on the basis of results obtained on small bar specimens

when tested as described in (8.2.1 – 8.5.6). *8.1.1 revised July 29, 1997*

8.1.2 Some materials, due to their thinness, distort, shrink, or are consumed up to the holding clamp when subjected to this test. These materials may be tested in accordance with the test procedure in Thin Material Burning Test; VTM-0, VTM-1, VTM-2... Section 11, provided specimens can be properly formed.

*8.1.2 revised July 29, 1997*

8.1.3 Table 8.1 specifies the material classifications.

Table 8.1
Materials classifications

*Table 8.1 revised July 29, 1997*

8.1.4 If only one specimen from a set of five specimens does not comply with the requirements, another set of five specimens is to be tested. In the case of the total number of seconds of flaming, an additional set of five specimens is to be tested if the totals are in the range of 51 – 55 seconds for V-0 and 251 – 255 seconds for V-1 and V-2. All specimens from this second set shall comply with the appropriate requirements in order for the material in that thickness to be classified V-0, V-1, or V-2.

*8.1.4 revised July 29, 1997*

8.1.5 Type 66 nylon materials classed V-2 shall have a relative viscosity (RV) of less than 120 in the supplied form, as determined by the method specified in 8.1.6, or if the relative viscosity is 120 or greater, the relative viscosity of the molded specimen shall not be less than 70 percent of the relative viscosity in the supplied form. *8.1.5 revised July 29, 1997*

8.1.6 The relative viscosity is to be determined by the solution method in ASTM D789, using either a pipet or Brookfield viscometer.

8.2 Test apparatus

8.2.1 See 5.1, 5.2, 5.5 – 5.8, 5.10, 5.12 – 5.15, 5.20 and 5.21.

8.3 Test specimens

8.3.1 All specimens are to be cut from sheet material, or are to be cast or injection, compression, transfer or pultrusion molded to the necessary form. After any cutting operation, care is to be taken to remove all dust and any particles from the surface; cut edges are to have a smooth finish. Fabrication of test specimens shall be in accordance with current ASTM Practices.

8.6 Results

8.6.1 The following are to be observed and recorded:

a) Afterflame time after first flame application, t .

1

b) Afterflame time after second flame application, t .

2

c) Afterglow time after second flame application, t .

3

d) Whether or not specimens burn up to the holding clamp.

e) Whether or not specimens drip flaming particles that ignited the cotton indicator.

*Figure 8.1 title revised July 29, 1997*

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