Device for preventing sewage backup in drain lines

Abstract From the Canadian patent

A device for automatically preventing the backup of sewage in a gravity discharge drain line consisting of an expansible bladder in conjunction with a reverse flow detector, means for inserting said device to a remote section in said drain line, a pressure source for expanding said bladder to a predetermined pressure and volume to block reverse flow upon signal from said reverse flow detector electrical and mechanical means for remote automatic operation of said device, said electrical and mechanical means containing elements for return of said device to normal standby position when the backup condition is rectified. In additions the device contains a self cleaning feature and means for …