The sewage ejector consists of a cast iron body, fitted with inlet and outlet pipes and valves. The sewage passes through the inlet valve into the ejector body and lifts a float. This float is connected to the automatic Movement Valve which opens, lets a supply of compressed air into the ejector body and this drives the sewage out of the ejector and up the delivery main. When the float drops the supply of compressed air is shut off and the air is exhausted from the ejector body. The ejector is fitted with specially designed self-cleaning Reflux Valves on the inlet and outlet sides.
The float and operating mechanism are a simple arrangement and as the Reflux Valves flaps and the float are the only moving parts in the sewage and minimum pipe work diameter is 4” (100mm), the Ejector is very good at raising unscreened sewage.
Image from Sewage Disposal Machinery - Adams Hydraulics Ltd