Electrolytic cell with differential gas pressure control device

A differential gas pressure control device for an electrolytic cell which cell comprises at least one anode compartment containing at least one anode at which in operation a gas is generated, at least one cathode compartment containing at least one cathode at which in operation a gas is generated, a separator positioned between each anode and adjacent cathode, a pipe leading from the anode compartment(s) of the cell through which in operation anode gas passes and a pipe leading from the cathode compartment(s) of the cell through which in operation cathode gas passes, in which the control device comprises a moveable flow controller positioned so as to control the flow of anode gas in said pipe and a moveable flow controller positioned to control the flow of cathode gas in said pipe, in which the flow controllers are operatively connected, and in which in operation the anode and cathode gases independently act upon the flow controllers which control the flow of cathode gas and of anode gas respectively.