A sewage ejector serving fixtures below the sewer must discharge upward and then into the gravity building drain. What fitting protects the pump from gravity backflow when it is off?

Explanation

The pump discharge must have a check valve to prevent effluent from draining back into the sump when the pump stops, and a gate (shutoff) valve downstream of the check so the check can be serviced. Without the check valve, each cycle would refill the sump and short-cycle the pump. This is standard for ejector and sump pump discharge piping.