1 Scope
This standard specifies the test methods and procedure for determining the thermal shock endurance for laboratory glassware.
This standard does not apply to apply to fused silica ware and soda-lime-silicate glassware.
The thermal shock endurance test methods of soda-lime-silicate glassware shall be in accordance with GB/T 4547.
2 Normative References
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments to (excluding amending errors in the text), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of standard applies.
GB/T 4547 Glass Containers - Test Methods of the Thermal Shock Resistance and Thermal Shock Endurance (GB/T 4547-2007, ISO 7459:2004, IDT)
3 Terms and Definitions
For the purpose of this standard, the following terms and definitions apply.
3.1
Thermal shock
A sudden change in temperature applied to laboratory glassware.
3.2
Thermal shock endurance Δt50
A temperature difference interpolated by linear regression at which 50% of the samples will probably fail.
3.3
Temperature variation
The difference at any moment between the temperature at the center of the working space and at any other point in the working space of the cold water bath or the test oven.
4 Apparatus
4.1 Cold water bath
Capable of containing at least five times the total volume of the samples being tested at one time. It shall be fitted with a water circulator, a thermometer and a thermostatic control capable of maintaining the water temperature to within ±1℃ of a specified lower temperature, t2, within the range of 0℃ to 27℃.
Note 1: the total volume of the samples is taken as the sum of the volume of the individual samples when each is regarded as being solid.
4.2 Test oven
The temperature ranges up to at least 300℃. It shall be fitted with an air circulating device to ensure that the temperature variation does not exceed ±5℃ and a thermostatic control capable of maintaining the test oven temperature fluctuation within ±1℃ up to 180℃ and within ±2℃ between 180℃ and 300℃.
4.3 Tongs
The tools with tips protected by a heat resisting material such as glass or mineral wool. 4.4 Gloves
Gauntlet-type and preferably made from an asbestos-substitute material.。
4.5 Basket
For testing two or more samples simultaneously. It shall be made out of a material which will not scratch or scuff the samples during the test procedure. It shall be capable of holding the samples upright and separate and of allowing a free passage of water and air between them. It shall prevent the sample from floating when immersed. It may be combined with an automatic device for placing the basket of samples in the test oven and transferring it to the cold water bath.
