Three types of residue from Arabian crude were blown in a 150l capacity pilot vertical converter and no scale effect was found for the same stock when the distilled oil was totally refluxed. In this investigation the blowing conditions did not affect the relations of penetration, softening point and ductility for the same stock.
The penetration of asphalt under process of blowing can be predicted easily from the softening point determined by the rapid method proposed by the authors, i. e. the application of P. I. diagram prepared from the same stock. The penetration can also be predicted from the total oxygen consumption.
Direct injection of water into asphalt during the blowing process is effective mean of controlling its reaction temperature and its cooling efficiency has been found to be high.