... during filtration process, as well as has greater backflow check valve function while backwash process.4.Split assembled filter cartridge ... from outside. While in backwashing, upper automatic air check valve will open automatically, air can come into the chamber, ... , 6 - 8 flange ;Drain (D): 3 flange Backwash valve (E): plastic material, 3 victaulic System controller (F): automatic dedicated ...