Counter Pressure Casting (CPC) is a further development of conventional low-pressure casting. It was developed in Bulgaria for casting armour wheels in the 1960s. Counter pressure casting is similar to low pressure casting, but it is operating with two pressure chambers – one for the molten metal and the other for the casting mould. Both chambers are pressurized at the same time at equal working pressure, which can reach the value up to 0.4 MPa. The furnace pressure then increases again by approximately 100 kPa. This allows metal to rise in the filling tube into the casting cavity at a controlled rate. The metal is displaced under a pressure differential, which can be exactly controlled by a valve system regulating the separate gas pressures in the furnace and in the mould cavity. The mould is filled with a pressure difference which corresponds to low pressure casting. But the working pressure is three to four times higher than that in low pressure casting, which brings many benefits.