The Crucible Test Method for Defining Noncombustible Materials Available to Purchase

It is observed that in many construction projects, both marine and land based, it has been advantageous to use materials of low combustible content. A modified oxygen bomb calorimetric test method is considered to define the total heat release content of the material. Such a method though suffers by the imposition of combustion processes quite unlike those during a real fire. It is suggested that a test method which only assesses the heat produced by combustion of volatiles can better assess the fire hazards associated with construction materials. The crucible test method for measuring heat content of volatile gases is described and the results of its application to a variety of materials is explored. It is shown that for a variety of mineral and glass wool insulation materials formed with a single binding agent that the heat release per unit weight is linearly related to the loss of weight on heating. For cellulosic materials both in the form of woods and fabrics the volatile heating power is significantly lower than the heat of combustion. Fire retardant treatment of these materials results in a further significant reduction (about 50 percent) in the volatile heating power. A brief exploration of limitations and performance characteristics of the test method are presented. A brief concluding discussion is presented in which it is reported that in France consideration is being given to a limit of 800 J/g as suitable for defining the line of demarcation between combustible materials and those considered noncombustible.