Other criteria on general physical and mechanical strength of glass packaging is tamper resistant internal pressure. Probably few of you have asked about what internal pressure could sustain a bottle designed to store carbonated liquids, given that a tire is loaded with about 2 atm.
Cylinders are designed to store champagne or sparkling wine must have resistance to internal pressure of at least 18 atm. Another interesting fact is that some brands of soft drinks have required the manufacturer of glass packaging, resistance to internal pressure is above 30-35 atm. This indicator depends on many factors – the design of the packaging, chemical composition of the molten glass defects of workmanship, thinning walls, irregular transitions in double – bottom rounded body inhomogeneity of molten glass, high internal stresses and others. As a rule it can be said that the cylindrical shape of the package implies a higher resistance, and internal pressure. The cylinders with the lowest resistance are those who have a square cross-section of the body. This is the reason for the high fragility of such products in the filling lines, transport, storage and trade.
Methods which can determine the resistance to internal pressure were:
- Standard method – increasing pressure is applied to a specified value set in the legal document.
- Loading and subsequent retention – increasing pressure to perform a certain value and retention at this value for a specified period of time;
- Testing With the constantly increasing internal pressure to burst;
- Testing by sudden hammering;
- Testing by impulses to breakage.
Our apparatus for measuring the resistance to internal pressure is manufactured by leading companies worldwide – American glass research and is capable of measuring the above methods.