Large Diameter Borosilicate Pyrex Glass Tube
Heat resistance of large diameter pyrex borosilicate glass tube
Glass tubes are poor conductors and brittle materials. We often see that glass water glasses burst. But the 3.3 borosilicate glass sight glass is different. Because of the chemical composition of 12.7% boron trioxide, its thermal stability is greatly improved. According to the provisions of ISO3587, the 3.3 borosilicate glass tube products are heated to 140℃ in an oven, keep the temperature for 30 minutes, immediately take it out and put it into 20℃ In water, the glass tube will not burst. This index is called the thermal shock temperature. ISO3587 stipulates that if the diameter of 3.3 borosilicate glass tube products is less than 100mm, the thermal shock resistance temperature shall not be less than 120℃ ; 3.3 borosilicate glass products with φ greater than 100mm, the thermal shock resistance temperature shall not be less than 110℃ . This means that the borosilicate glass tube is heated 140℃ or 130℃ . When suddenly encountered the cold water of 20℃ will not burst the glass tube. In actual use, since people know that hot glass tubes are afraid of cold water, they generally do not get cold water on the hot glass tubes. But in the production using glass tube equipment, the temperature is greater than 120℃ . The situation of heated to 100℃ with glass equipment is many. When the temperature is above 100℃, make sure that cold water splashes will not burst.
The thermal expansion and contraction of the 3.3 borosilicate glass tube is very small. Take a 10m long tube as an example, if the temperature is increased by 50K, the elongation value of the glass tube is equal to 1; the steel is 3.6; the polyethylene is 62.5. Therefore, the glass pipe can even not use the telescopic compensator.