ISO 2254:1980

Gives the definition, classification and designation of shaped insulating refratory materials. According to the definition they have a total porosity of at least 45%. One distinguishes between high alumina products, fireclay and siliceous fireclay products, semi-silica products, silica products, basic products and special products. High alumina, fireclay and siliceous fireclay products are subdivided depending on the temperature at which the material does not show any permanent linear change in dimension greater than 2% at the end of a conventional test.