Fire Safety Science Digital Archive

The preparation of unplasticised polyvinyl chloride powder (PVC) by grinding can result in the release of vinyl chloride into the head space of grinders etc. Although PVC powder is non-explosible in the standard tests for the explosibility of dust clouds, the combination of PVC powder and vinyl ohloride may be explosible. Tests were undertaken to study the explosibility of PVC powder suspensions in an atmosphere of air and methane, below the lower explosibile limits (LEL) of the methane. Methane was used in place of vinyl chloride as a toxicologically safe substitute. It is concluded that methane exercises a strong influence on PVC powder suspensions causing the minimum explosible concentration to be reduced.