A specific mark on each plate allows identification even when they do not have the same function. Several identification codes are used.

· Coloured Cloth Pegs.
· Coloured Spigot tabs.
Coloured code used is as under
– Red for Washed plates
– Blue for Pressure plates.
– Black for End plates.
· Identification numbers with bar coding on each plate
· Permanent marks on the side face of the plates.

To differentiate Recessed chamber plates and a Membrane plates is easy due to presence of two membranes on both sides of the plate but again colored code make different pressure and washed plates.