Patent ID: 7758734

Claim:
An electrochemical sensor for measuring the amount of hydrogen sulphide or thiols in a fluid, the sensor comprising a housing having a flow path for the fluid therethrough, a substantially rigid gas permeable membrane disposed in the housing and having one side exposed to the flow path, and a chamber disposed in the housing, the chamber being exposed to the other side of the membrane and containing reagents which together with the hydrogen sulphide or thiols entering the chamber via the membrane create a redox reaction resulting in an electrical current dependent upon the amount of hydrogen sulphide or thiols in said fluid; wherein the housing is provided with one of a movable piston, partition or bellow for reducing a difference between the respective pressures on each side of the membrane and wherein the one of a movable piston, partition or bellow comprises a first pressure surface in pressure communication with the flow path and a second pressure surface in pressure communication with the chamber.