GB/T 10707-2008 English PDF (GBT10707-2008)

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GB/T 10707-2008: Rubber -- Determination of the burning
GB/T 10707-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.140.01
G 40
Replacing GB/T 10707-1989, GB/T 13488-1992
Rubber - Determination of the burning
ISSUED ON. JUNE 04, 2008
IMPLEMENTED ON. DECEMBER 01, 2008
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Terms and definitions ... 5 
4 Methods A - Oxygen index method ... 6 
4.1 Principle of test ... 6 
4.2 Test device ... 6 
4.3 Specimen ... 8 
4.4 Test procedure ... 8 
4.5 Calculation of results ... 10 
4.6 Test report ... 12 
5 Method B - Vertical burning method ... 12 
5.1 Principle of test ... 12 
5.2 Test device ... 12 
5.3 Specimen ... 13 
5.4 Test procedure ... 14 
5.5 Calculation of results ... 15 
5.6 Evaluation of results ... 16 
5.7 Test report ... 17 
Appendix A (Normative) Calculation of oxygen concentration ... 18 
Appendix B (Informative) Relationship between oxygen concentration and
oxygen, nitrogen flow rate ... 19 
Appendix C (Informative) Calculation example of test result ... 24 
Appendix D (Informative) Schematic diagram of a Bunsen lamp with scaled pole
... 26 
Rubber - Determination of the burning
1 Scope
This standard specifies two methods for determining the burning properties of
rubber in a laboratory environment. the oxygen index method (method A) and
the vertical burning method (method B).
This standard is applicable to evaluate the burning properties and flame-
retardant properties of rubber materials in a laboratory environment. It is not
suitable to evaluate the fire hazard of rubber materials under actual use
conditions.
2 Normative references
The provisions in following documents become the provisions of this standard
through reference in this standard. For the dated references, the subsequent
amendments (excluding corrections) or revisions do not apply to this standard;
however, parties who reach an agreement based on this standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
GB/T 2941-2006 Rubber - General procedures for preparing and
conditioning test pieces for physical test methods (ISO 23529.2004, IDT)
GB/T 3863 Industrial oxygen
GB/T 3864 Industrial nitrogen
HG/T 3095 Fire tests terms for rubber
3 Terms and definitions
The terms and definitions as established by HG/T 3095 as well as the following
terms and definitions apply to this standard.
3.1
Oxygen index
Under the specified test conditions, in a mixed-gas of oxygen and nitrogen
at 23 °C ± 2 °C, the minimum oxygen concentration (expressed as a volume
4.3 Specimen
4.3.1 The specimen size is length 80 mm ~ 150 mm, width 6.5 mm ± 0.5 mm,
thickness 3 mm ± 0.25 mm.
4.3.2 The preparation and conditioning of the specimen shall be carried out in
accordance with the requirements of GB/T 2941-2006.
4.3.3 In order to facilitate the measurement of the burning length of the
specimen, mark it at a distance 50 mm from the ignition end of the specimen.
4.3.4 For the rubber materials with a known oxygen index value range within ±
2, it shall prepare 15 specimens; for the rubber materials with unknown oxygen
index or unstable burning features, prepare 15 ~ 30 specimens.
4.4 Test procedure
4.4.1 Check the test device to ensure it is in good condition. The burning
cylinder should be placed vertically. The specimen is clamped vertically on the
specimen holder at the center of the cylinder. The top of the specimen is at least
100 mm from the cylinder mouth.
4.4.2 Based on experience or the burning of the specimen in air, estimate the
oxygen concentration at the start of the test. If the specimen is burned rapidly
in air, the oxygen concentration (volume fraction) is estimated at 18%; if the
specimen is burned slowly or unstably, it is estimated at 21%; if the specimen
does not catch fire in the air, it is estimated at least 25%. The calculation formula
for the oxygen concentration is as shown in Appendix A.
4.4.3 After determining the oxygen concentration according to 4.4.2, adjust the
flow rate of the mixed-gas of oxygen-nitrogen (see Appendix B for the flow rate
of oxygen and nitrogen) and let it flow for at least 30 s in the burning cylinder,
to remove the air from the burning cylinder. Before test, each specimen shall
be subjected to this procedure, to ensure that the gas flow in the burning
cylinder does not change during the ignition and burning of the test. In the
ignition and burning process, it shall not change the gas flow rate and gas
concentration of oxygen-nitrogen.
4.4.4 Ignite the ignitor, adjust the flame to the specified length, extend the
ignitor’s nozzle into the burning cylinder. Allow the flame to fully contact the top
surface of the specimen, but not the side surface. The flame application time is
not more than 30 s, move away the ignitor every 5 s to observe whether the
specimen is ignited. If the entire top surface of the specimen is burned, the
specimen is considered to have been ignited, then start timekeeping
immediately or otherwise measure the burning length.
The oxygen index which is calculated according to 4.5.1 is credible, otherwise.
If d < 2σ/3, increase the d value, repeat the operations of 4.4.9 ~ 4.4.11, until
the condition is satisfied;
If d > 3σ/2, when d = 0.2%, the oxygen index is considered to be credible.
However, when d > 0.2%, decrease the d value, repeat the operations of 4.4.9
~ 4.4.11, until the condition is satisfied.
4.5 Calculation of results
4.5.1 Oxygen Index (OI)
The formula for calculation of the oxygen index (OI) is as shown in formula (1).
Where.
OI - The oxygen index expressed by the volume fraction, which retains two
decimal places in the calculation, and only one decimal place in the report;
cf - The final oxygen concentration expressed by the volume fraction, which
retains one decimal place;
k- Coefficient, the determination method of which is as shown in 4.5.2;
d - The oxygen concentration level difference expressed by the volume
fraction, which retains one decimal place.
4.5.2 Determination of k value
The k value and its positive-negative sign are dependent on the features of the
specimen, which can be determined from Table 1 as follows.
4.5.2.1 If the feature “0” is obtained by the test in 4.4.8, then the first opposite
feature (see 4.4.9) shall be “X”. From the last four feature arrangements per
row in the first column of Table 1, find the row that is exactly the same as the
feature arrangement as obtained in 4.4.10. Then, based on the number of
features “0” as obtained in 4.4.8 and 4.4.9, find the column with the same
number from the row (a). The intersection of rows and columns is the calculated
k value.
4.5.2.2 If the feature “X” is obtained by the test in 4.4.8, the first opposite feature
shall be “0”. From the arrangement of the last 4 features per row in column 6 of
Table 1, find the row that is exactly the same as the feature arrangement as
obtained in 4.4.10. Then, based on the number of features “0” as obtained in
Note. The thickness of the specimen can be other sizes, but the test results
cannot be compared with the test results of the standard specimen, they shall
be indicated in the test report. ...