Automatic sewer back-up valve

Claim 1

IN A VALVE APPARATUS FOR CONTROLLING BACK-UP FLOW IN A SEWER LINE, THE COMBINATION OF A PIPE LINE FOR DISCHARGING SEWAGE FROM AN INHABITED STRUCTURE TO A SEWER, AN INTERNAL FLOW SLEEVE HAVING A DISCHARGE END OF SMALLER DIAMETER THAN SAID PIPE LINE MOUNTED WITHIN A PORTION OF SAID PIPE LINE IN THE PATH OF LIQUID FLOW THEREIN AND PROVIDING AN ANNULAR CHAMBER BETWEEN SAID SLEEVE AND SAID PIPE LINE, A LIQUID-LEVEL SENSING DEVICE DISPOSED EXTERIORLY OF SAID PIPE LINE, THE WALL OF SAID PORTION OF SAID PIPE LINE BEING PROVIDED WITH OPENINGS BEING FLOW COMMUNICATION BETWEEN SAID ANNULAR CHAMBER AND SAID LIQUID-LEVEL SENSING DEVICE, SAID OPENINGS BEING SHIELDED BY SAID SLEEVE FROM EXPOSURE TO THE DISCHARGE FLOW OF LIQUID IN ITS NORMAL DIRECTION OF MOVEMENT IN SAID PIPE LINE, BUT BEING EXPOSED TO BACK-UP FLOW OF LIQUID INTO SAID ANNULAR CHAMBER, AND VALVE MEANS ACTUATED BY SAID LIQUID-LEVEL SENSING DEVICE IN RESPONSE TO A PREDETERMINED LEVEL OF BACK-UP FLOW INTO SAID CHAMBER AND THROUGH SAID OPENINGS FOR SEALING SAID DISCHARGE END OF SAID SLEEVE AGAINST SAID BACKUP FLOW.