THIS DRAWING SHOWS ONE VERSION OF THE ENVIROSAFE PUMP DRAIN INSERT INSTALLED IN A STRAIGHT PIPE RATHER THAN A TYPICAL HUB OR REDUCER.  THE TAPERED PORTION FORMS A HUB TO ALLOW FOR MORE VOLUME TO FLOW TO THE DRAIN.  THE PUMP DRAIN INSERT PROVIDES CONTINUOUS FLOW WHILE MAINTAINING A WATER SEAL THAT PREVENTS HYDROCARBONS FROM ESCAPING TO THE ATMOSPHERE, THEREBY COMPLYING WITH EPA AIR QUALITY REGULATIONS RESTRICTING EMISSIONS OF VOC'S SUCH AS BENZENE.   DRAIN LINES SHOULD BE PIPED INTO THE DRAIN SO AS TO ALLOW FOR REMOVAL OF THE CAP FOR FLUSHING TO REMOVE ANY HYDROCARBONS FLOATING ON THE WATER SEAL.  A MINIMUM WATER SEAL DEPTH OF 6" IS RECOMMENDED TO PREVENT BACK PRESSURE FROM FORCING ANY HYDROCARBON VAPORS THROUGH THE WATER SEAL ONCE THE SEWER SYSTEM HAS BEEN SEALED.  THE PUMP DRAIN INSERT CAN PREVENT SEWER EXPLOSIONS BY ELIMINATING CONTACT OF SEWER GASES WITH AN IGNITION SOURCE.

COVERED BY U.S. PATENT NO.'S    4,682,907;    4,776,722;     5,028,320;    5,062,735