A dispensing apparatus is provided for mixing and spraying A and B components of urethane foam plastic whereby urethane foam plastic may be sprayed in place. The gun includes structure whereby a solvent for the A and B components may be readily utilized to thoroughly flush the A and B component valves,...http://www.google.es/patents/US4202497?utm_source=gb-gplus-sharePatente US4202497 - Spray gun
