GB/T 40717-2021 English PDF (GBT40717-2021)

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GB/T 40717-2021: Fire-retardant tyres
GB/T 40717-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.160.01
CCS G 41
Fire-retardant tyres
阻燃轮胎
ISSUED ON: OCTOBER 11, 2021
IMPLEMENTED ON: MAY 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 4 
4 Special mark ... 5 
5 Technical requirements ... 5 
6 Test methods ... 6 
Fire-retardant tyres
1 Scope
This document specifies the special mark, technical requirements, and related
performance test methods for fire-retardant tyres.
This document is applicable to truck tyres and passenger car tyres with fire-
retardant performance requirements.
2 Normative references
The contents of the following documents, through normative references in this
text, constitute indispensable provisions of this document. Among them, for
dated references, only the edition corresponding to that date applies to this
document. For undated references, the latest edition (including all amendments)
applies to this document.
GB/T 2941 Rubber - General procedures for preparing and conditioning test
pieces for physical test methods
GB/T 6326 Tyre terms and definitions
GB/T 10707 Rubber - Determination of the burning
3 Terms and definitions
The terms and definitions defined in GB/T 6326 and the following ones apply to
this document.
3.1
Fire-retardant tyre
A tyre which self-extinguishes when away from the fire under the specified test
conditions.
3.2
Oxygen index
The minimum oxygen concentration (expressed in volume fraction) which
maintains the combustion of rubber materials in a mixed gas stream of oxygen
compound, the measured oxygen index of tread rubber and sidewall rubber
shall not be less than 24%.
6 Test methods
6.1 Parking of test tyre sample
Before the test, the finished tyre shall be parked in a test environment of
18 °C~36 °C. The parking time shall not be less than 24 h.
6.2 Test of tyre fire-retardant performance
6.2.1 Test equipment
Portable flamethrower (the combustion temperature of outer flame is
1250 °C~1350 °C, such as butane flamethrower); stopwatch.
6.2.2 Test procedure
6.2.2.1 Erect the test tyre (not inflated) vertically and fix it on the concrete or
cement floor.
6.2.2.2 Take a point in the middle of the crown on the cut surface of the tyre
crown perpendicular to the ground (avoid the groove); use "+" to mark it (as
shown in Figure 2).
6.2.2.3 Take a point at the center of the sidewall directly above the tyre crown
that is in contact with the ground; use "+" to mark it (as shown in Figure 2).
6.2.2.4 Take a point at the bead heel directly above the tyre crown that is in
contact with the ground; use "+" to mark it (as shown in Figure 2).
6.2.2.5 Under the condition of not being close to the test tyre, after the
flamethrower is activated and set to the maximum gear, vertically align the outer
flame of the fire source at the "+" marking points to spray and start timing. After
10 s, immediately turn off the fire source and remove; observe the burning state
at the marking points and make a judgment.