Boiling flask, flat bottom, narrow neck

LBG 3.3 is a borosilicate glass with a minimum content in silica of 80% and a low expansion coefficient (3.3•10-6
K-1) included in the 3.3 borosilicate group, as defined in ISO 3585 standard.
It is used in products where chemical and mechanical resistance is to be combined with resistance to sudden
temperature changes. This particular combination of properties makes this type of glass the most used in labware.
Physical and chemical properties:
Linear expansion coefficient (@ 20/300 ºC): 3.3•10-6 K-1 
Strain point: 520 ºC 
Annealing point: 560 ± 10 ºC 
Softening point: 820 ± 10 ºC 
Density: 2.23 ± 0.02 g/cm3 
Hydrolytic resistance (according to ISO 719, water at 98 ºC): Class 1 
Hydrolytic resistance (according to ISO 720, water at 121 ºC): Class 1 
Resistance to acids (according to ISO 1776, DIN 12116): Class 1 
Resistance to alkalis (according to ISO 695): Class 2
Typical composition:
80.4% in weight SiO2 
13.0% in weight B2O3 
4.2% in weight Na2O 
2.4% in weight Al2O3