Tests Run to Determine the Effect of Blanket Washing on the Concentration of Combustible Vapor in the Dryer of a Heatset Web Offset Press.

A series of tests dealing with the combustible vapor concentration in the dryer of a heatset web offset press were carried out. Variables measured included normal printing, automatic blanket washing, and decay to a white web. Results showed that with single-zone dryers, the combustible vapor concentration decreases during simultaneous cleaning of all blankets. However, manual cleaning slightly increased combustible vapor concentration. Dryer set-up and operation, flame ionization detectors, and washup solvents are discussed.