Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization — Part 1: Rules for the structure and drafting of standardizing documents.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This document was proposed by China Petroleum and Chemical Industry Federation.
This document is under the jurisdiction of National Technical Committee on Tyres and Rims of Standardization Administration of China (SAC/TC 19).
Test method for air retention of motor vehicle tyres
1 Scope
This document specifies the test method for air retention of motor vehicle tyres in static, including test equipment, test conditions, test procedure, data processing and test report.
This document is applicable to the tests for air retention of tubeless passenger car tyres and truck tyres.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 2977 Size designation, dimensions, inflation pressure and load capacity for truck tyres
GB/T 2978 Size designation, dimensions, inflation pressure and load capacity for passenger car tyres
GB/T 6326 Tyre terms and definitions
HG/T 2177 Appearance quality of tyres
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 6326 and the following apply.
3.1
inflation pressure loss rate
change of revised inflation pressure, obtained from the slope of the straight line where the logarithm of inflation pressure is fitting with the time curve
3.2
measured inflation pressure
inflation pressure measured within a specified time period at ambient temperature and atmospheric pressure
?
3.3
revised inflation pressure
inflation pressure at one standard atmospheric pressure and nominal temperature, which is revised from a measured inflation pressure according to the definition of ideal gas
3.4
nominal temperature
reference temperature of a temperature control room specified in a test
4 Test equipment
4.1 General
The test equipment includes tyre inflation pressure sensors, ambient temperature sensors, atmospheric pressure sensors, adapters connecting tyres and tyre inflation pressure sensors, and computers and systems for recording and analyzing test data.
4.2 Tyre inflation pressure sensor
The accuracy is ±0.25% of the measured value.
4.3 Atmospheric pressure sensor
The range is 80 kPa ~ 120 kPa, and the accuracy is ±0.25% of the full scale.
4.4 Ambient temperature sensor
The range is 0°C ~ 50°C and the accuracy is ±0.2°C.
5 Test conditions
5.1 The average ambient temperature of the temperature control room shall be controlled at ±0.6°C of the nominal temperature, and during the whole test, the temperature change shall be controlled within ±3°C. The nominal temperature is 21°C, 24°C, 30°C, 38°C or other values. The air in the temperature control room shall circulate evenly to reduce the temperature difference.
5.2 Tyres shall be kept at room temperature for more than 24 hours after vulcanization. Before inflation, they shall be kept at 18°C ~ 36°C for more than 3 hours.
5.3 At least two tyres for each size designation shall be selected for testing.
5.4 The appearance of tyres shall meet the requirements of HG/T 2177.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Test equipment
5 Test conditions
6 Test procedure
7 Data processing
8 Test report
