Electrochemical system , having: o a fuel cell , having an inlet manifold (Ce) and an outlet manifold (Cs) that are designed to ensure a flow of a supply fluid through the fuel cell ; o a source of said supply fluid, connected to the inlet manifold (Ce) by a fluidic supply line (La); o a fluidic outlet , connected to the outlet manifold (Cs) by a fluidic discharge line (Le), and intended to be brought to a constant outlet pressure; o a regulator , disposed on the fluidic supply line (La), designed to regulate, as a function of a setpoint pressure P c , a downstream pressure P av of the supply fluid at the outlet of the regulator and therefore an inlet pressure of the supply fluid in the fuel cell , and having: • an internal duct situated on the fluidic supply line (La); • at least one valve having a mobile part designed to shut off or not shut off the internal duct depending on whether or not the downstream pressure P av is greater than the setpoint pressure P c ; • at least one membrane to which is fastened the mobile part , the membrane separating, on one side, a zone of the internal duct that is situated downstream of the valve, and on the other side an internal chamber ; o a purge valve , disposed on the fluidic discharge line (Le) between the outlet manifold (Cs) and the fluidic outlet ; o characterized in that the regulator has a pressurisation duct connecting the internal chamber to a zone of the fluidic discharge line (Le) that is situated downstream of the purge valve . o a fuel cell , having an inlet manifold (Ce) and an outlet manifold (Cs) that are designed to ensure a flow of a supply fluid through the fuel cell ; o a source of said supply fluid, connected to the inlet manifold (Ce) by a fluidic supply line (La); o a fluidic outlet , connected to the outlet manifold (Cs) by a fluidic discharge line (Le), and intended to be brought to a constant outlet pressure; o a regulator , disposed on the fluidic supply line (La), designed to regulate, as a function of a setpoint pressure P c , a downstream pressure P av of the supply fluid at the outlet of the regulator and therefore an inlet pressure of the supply fluid in the fuel cell , and having: • an internal duct situated on the fluidic supply line (La); • at least one valve having a mobile part designed to shut off or not shut off the internal duct depending on whether or not the downstream pressure P av is greater than the setpoint pressure P c ; • at least one membrane to which is fastened the mobile part , the membrane separating, on one side, a zone of the internal duct that is situated downstream of the valve, and on the other side an internal chamber ; • an internal duct situated on the fluidic supply line (La); • at least one valve having a mobile part designed to shut off or not shut off the internal duct depending on whether or not the downstream pressure P av is greater than the setpoint pressure P c ; • at least one membrane to which is fastened the mobile part , the membrane separating, on one side, a zone of the internal duct that is situated downstream of the valve, and on the other side an internal chamber ; o a purge valve , disposed on the fluidic discharge line (Le) between the outlet manifold (Cs) and the fluidic outlet ; o characterized in that the regulator has a pressurisation duct connecting the internal chamber to a zone of the fluidic discharge line (Le) that is situated downstream of the purge valve . <EOS>