Quality Indicators

Norm

Mass fraction of Al₂O₃, %, not less

28

32

33

Fire resistance, °C, not lower

1670

1690

1710

Residual change in dimensions when heated at a temperature of 1350 °C, %, no more

0,5

0,4

0,4

Open porosity, %

15-26

15-24

15-24

Thermal resistance of center, span and end siphon tubes, heat changes (heating up to 800 °C, cooling in air)

1

1

2