【Article overview】The key difference lies in their chemical properties: The national standard for water resistance of the inner surface of low-borosilicate ampoules is 2.6 mm, while that for medium-borosilicate ampoules is 1.3 mm. Both types exhibit excellent performance in terms of transparency and stability.

1. The key difference lies in their chemical properties: The national standard for water resistance of the inner surface of low-borosilicate ampoules is 2.6 mm, while that for medium-borosilicate ampoules is 1.3 mm. Both types exhibit excellent performance in terms of transparency and stability.

2. Physical Properties: The medium-boron vials have very tight dimensional tolerances and match well with production equipment. Low-borosilicate ampoules exhibit high acid resistance but show significant batch-to-batch variability. For example, the outer diameter tolerance for 16-tube vials is ±0.3 mm, and they are green in color—making it difficult to match them with imported or high-end equipment.

The main differences between neutral glass and low-borosilicate ampoules and soda-lime glass lie in its superior thermal stability and chemical resistance. It also differs from high-borosilicate glass in terms of its coefficient of thermal expansion and boron trioxide content. The identification criteria are as follows:

(1) Linear thermal expansion coefficient: This is one of the key physical properties of glass. It determines the thermal stability of glass—the glass’s ability to withstand temperature changes—and is primarily governed by the chemical composition of the glass. Therefore, using the linear thermal expansion coefficient as a performance evaluation index not only allows for precise control of glass properties but also provides insight into the types of constituents present in the glass.

(2) Boron trioxide content: This is the primary component for enhancing both the thermal and chemical stability of glass. Within a certain range, as its content increases, the glass’s performance improves accordingly. Therefore, determining the boron trioxide content serves as an important identification criterion—not only enabling control over the glass’s performance but also reflecting the types of components present in the glass. Currently, in neutral glasses, the B2O3 content is no less than 8% (by weight).

2. Water resistance by the particle method at 121℃: The determination and grading method for the water resistance of glass particles at 121℃ is adopted. Based on the material performance, the specified grade is Level 1. The chemical stability of the glass material is controlled.

3. The 98℃ Particle Method for Water Resistance Testing determines the water resistance of glass particles at 98℃. The 98℃ Particle Method is currently an internationally widely used and important approach for assessing the water resistance grade of glass. Neutral glass materials shall meet the requirements of HGB1 and ensure controlled chemical stability of the glass materials.

4. Test method and grading criteria for water resistance of internal surfaces at 121℃: The indicator requirement shall meet HC1, ensuring the chemical stability of glass bottles.

5. Acid resistance is primarily used to test the degree of acid corrosion resistance of glass, thereby quantitatively determining its acid-resistance grade. The first method is the gravimetric method. This method involves measuring the glass’s resistance to corrosion by boiling hydrochloric acid. The grade is determined based on the weight loss per unit surface area of the glass. Neutral glass should meet the requirements of Grade 1. The second method is flame spectroscopy, which is used according to the second approach. The qualification can be judged by the amount of alkaline oxides precipitated per unit surface area of the glass. For neutral glass, this amount should be less than or equal to 100 μg/dm². This ensures the chemical stability of glass bottles.

6. Alkali resistance primarily tests the degree to which glass is resistant to corrosion by mixed alkalis, thereby quantitatively determining the glass’s alkali resistance grade.

7. The internal stress method is a technique for measuring internal stresses, with ampoules serving as the measurement indicator. It is used to control the quality of the annealing process for glass bottles.

8. Using low-borosilicate ampoules as the reference, measure roundness using the vertical-axis deviation method. Ensure the flatness of the container bottom and overall symmetry.