Abstract: An electrochemical gas sensor has a working electrode having a gas porous membrane and a catalyst layer formed on one side of the membrane; a counter electrode, electrolyte in contact with the catalyst both of the working electrode and of the counter electrode; and a support that is in contact with, and presses against the side of the working electrode remote from the electrolyte and that compresses the electrodes and the electrolyte together. The support includes open areas enabling gas to contact the membrane. The support provides a faster response and provides greater efficiency of catalyst usage.

Abstract: There is disclosed a method of operating a colorimetric gas detector system that comprises a substrate (1) bearing a material (12) that can react with a target gas to produce a change in the wavelength of radiation absorbed or transmitted by the material (“color-change material”). The method involves: a) applying onto a region (15) of the substrate that includes color-change material a chemical of predetermined concentration that reacts directly or indirectly with the color-change material to produce a change in the wavelength of the radiation absorbed or transmitted by the material; b) detecting the radiation absorbed or transmitted in said region (15) at a wavelength absorbed or transmitted by the reaction product of the color change material with the chemical, and c) generating a signal in accordance with the amount of radiation detected at the second wavelength, said signal being dependent on the amount of color-change material on the substrate.

Abstract: The present invention provides a transmitter unit for an open path gas detector for detecting a target gas and comprises: a radiation transmitter, e.g. a tuneable laser diode, capable of emitting radiation at a wavelength absorbed by the target gas, and a radiation deflector, having a deflecting part and a non-deflecting part, e.g. a mirror having a non-reflective part. The deflecting part and the non-deflecting part are located in the path of the radiation emitted by the transmitter and the non-deflecting part does not deflect the said radiation emitted by the transmitter or does so to a different extent than the deflecting part. In this way, the beam has a core in shadow that can be used to align the beam with a receiver unit. The radiation deflector is preferably a mirror having a reflective surface for reflecting radiation emitted by the transmitter and a non-reflective part that does not reflect the said radiation emitted by the transmitter or does so to a lesser extent that the reflecting surface.

Abstract: A mineral acid detection tape includes a cellulose paper substrate saturated with a formula solution and provides an extended life detection tape of at least a three-month period of time when place in service.

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.