According to the physical and chemical indexes, the air permeable brick and block brick are divided into four grades: T-80, T-85, zb-80 and zb-85. Among them, t, Z and B represent the first Chinese pinyin letter of air permeable brick, seat brick and unburned respectively.

Executive standard: Yb / t4118-2003

The product has the characteristics of stable structure, large air permeability, high blowing rate, erosion resistance, long service life, etc. It is beneficial to the purification of molten steel, uniform composition and temperature, and is suitable for refining furnaces with long-term or special treatment of molten steel.

Project	indicators
	T-80	T-85	ZB-80	ZB-85
（AL2O3 + Cr2O3+ MgO ）%≥	92	92	92	92
AL2O3 %≥	80	85	80	85
Apparent porosity %   ≤	20	20	19	19
ormal temperature compressive strength MPa ≥	--	--	40	45
0.2MPa load softening start temperature ℃≥	1680	1680	1680	1680
Ventilation capacitym3 /h	Provide data		--