Abstract: This invention provides an assembly comprising a sensing electrode and a counter electrode in contact with a membrane body formed from a solid polymer electrolyte system comprising a fluorinated polymer matrix and a charge carrying component which is dispersed in the matrix the electrodes and membrane being housed in a housing having a gas diffusion barrier through which gas may flow. The charge carrying components are fluorinated organic proton conductors (such as heptadecafluorooctane sulphonic acid, bis-trifluoromethane sulphonamide, N-(2,6-diethylphenyl)-1,1,1-trifluoromethane sulphonamide, N-benzyltrifluoromethane sulphonamide and N, N-1,2-cyclohexanediylbis (1,1,1-trifluoromethane sulphonamide)). The polymer matrix is a homopolymer or copolymer of vinylidene fluoride preferably with fluorinated comonomers. The solid polymer electrolyte system preferably contains plasticising additive(s) and is cast as a coating onto one or more electrodes eg.

Abstract: A method and apparatus for gas detection uses a sensor such as an electrochemical (EC) cell and includes a feedback control loop to control a pump to establish a first predetermined gas flow rate to the EC cell. The concentration of the gas at the first predetermined flow rate is measured. If the detected concentration exceeds a predetermined Alert value at the first flow rate an Initial Warning without remedial action is generated, and, the system then changes the gas flow rate before an Alarm is indicated. An Alarm is signaled only if the system verifies the first measurement. Preferably the first flow rate is set to optimize the measurement accuracy of the EC cell being used, and the second flow rate is lower than the first. Verification of an Alarm at the first flow rate may be conducted quickly by a quick-reaction process. The controller may periodically cycle the flow rates between the first and second rates for better accuracy and faster verification times.

Abstract: A process is described for manufacturing gas diffusion electrodes, which process comprises: (a) treating an area of a pre-shrunk porous hydrophobic substrate so as to restrict the slurry deposited in step b) to the said area, preferably by forming a well in the area and/or treating the substrate in the area to render it less hydrophobic, e.g. by plasma treating the area; (b) dispensing a slurry of catalyst onto the said area, (c) removing liquid from the dispensed slurry, (d) treating the dried slurry to remove organic materials and e) cutting the catalyst and the underlying portion of substrate from the rest of the substrate.

Abstract: A method and apparatus for gas detection uses a sensor such as an electrochemical (EC) cell and includes a feedback control loop to control a pump to establish a first predetermined gas flow rate to the EC cell. The concentration of the gas at the first predetermined flow rate is measured. If the detected concentration exceeds a predetermined Alert value at the first flow rate an Initial Warning without remedial action is generated, and, the system then changes the gas flow rate before an Alarm is indicated. An Alarm is signaled only if the system verifies the first measurement. Preferably the first flow rate is set to optimize the measurement accuracy of the EC cell being used, and the second flow rate is lower than the first. Verification of an Alarm at the first flow rate may be conducted quickly by a quick-reaction process. The controller may periodically cycle the flow rates between the first and second rates for better accuracy and faster verification times.

Abstract: A monitor is disclosed for monitoring an atmosphere for the presence of a target gas, the monitor comprising:

Abstract: This invention provides an assembly comprising a sensing electrode and a counter electrode in contact with a membrane body formed from a solid polymer electrolyte system comprising a fluorinated polymer matrix and a charge carrying component which is dispersed in the matrix the electrodes and membrane being housed in a housing having a gas diffusion barrier through which gas may flow. The charge carrying components are fluorinated organic proton conductors (such as heptadecafluorooctane sulphonic acid, bis-trifluoromethane sulphonamide, N-(2,6-diethylphenyl)-1,1,1-trifluoromethane sulphonamide, N-benzyltrifluoromethane sulphonamide and N, N-1,2-cyclohexanediylbis (1,1,1-trifluoromethane sulphonamide)). The polymer matrix is a homopolymer or copolymer of vinylidene fluoride preferably with fluorinated comonomers. The solid polymer electrolyte system preferably contains plasticising additive(s) and is cast as a coating onto one or more electrodes eg.

Abstract: A gas sensor assembly comprises a housing (65) including a bore (61). A pin (50) extends through the bore (61) and an O-ring (100) is located in the bore. The O-ring (100) contacts the pin (50) and parts of the bore (61) so as to be restrained against movement in both lateral and axial directions. Two- and three-shot moulding processes are described for fabricating the assembly.

Abstract: An electrochemical gas sensor assembly comprises an electrochemical gas sensor; an electrolyte reservoir (3); and at least one capillary (9) defined by substantially rigid, non-porous walls for conveying electrolyte between the reservoir and the gas sensor.

Abstract: A half-cell reference electrode comprises an electrode member in electrochemical contact with at least one gelled electrolyte solution which itself is contactable with the liquid to be tested wherein the gelling agent comprises a polymer containing acrylamide units substituted with a group or groups which lower the polymer's tendency to hydrolyse compared to polyacrylamide while providing a polymer that can form a gelled solution in 2.6M sodium/potassium nitrate solution (2.21M potassium nitrate and 0.39M sodium nitrate) comprising at least 75% (w/w) sodium/potassium nitrate solution.

Abstract: An electrorheological fluid e.g. for selectively coupling clutch members consists of silicone oil containing 30 volume % of dispersed polyaniline. The polyaniline is acidically oxidised aniline subsequently treated with base.