Abstract: An optical particle counter determines the velocity of particles passing through a particle detection zone, and thereby the velocity of gas flow, from both the measured time of flight of discrete particles and also the size of intensity peaks of scattered light. This is used to determine particle concentration and may be used to control an optional fan.

Abstract: The invention relates to an electrochemical gas sensing apparatus for sensing one or more analytes, such as NO2 and/or O3, in a sample gas and a method of using same. The apparatus uses Mn2O3 as a filter for ozone. The Mn2O3 may take the form of a powder which may be unmixed, mixed with various PTFE particles sizes, formed into a solid layer deposited onto a membrane and/or pretreated with NO2.

Abstract: Particle measurement apparatus comprises an inlet for receiving a gas sample for analysis, a photoionisation chamber, at least one light source arranged to illuminate an interior of the photoionisation chamber, first and second electrodes coupled to a power source and configured to provide a DC potential difference across at least a portion of the photoionisation chamber, and an outlet, together defining a gas flow path from the inlet, through the photoionisation chamber, and towards the outlet.

Abstract: A gas analyzer and a corresponding method is provided to measure the concentration of formaldehyde within enclosed environments such as within buildings comprising an ultraviolet light source, a sample chamber, a detector. The detector measures the intensity of light received by photosensors within a measurement range of wavelengths, and at least one reference range of wavelengths. Advantageously, the concentration of formaldehyde is determined taking into account fluctuations in the intensity of light emitted by the light source, and in the presence of any interferents such as nitrogen dioxide.

Abstract: A gas analyser is provided to measure the concentration of formaldehyde within enclosed environments such as within buildings comprising an ultraviolet light source, a sample chamber, a detector. The detector measures the intensity of light received by photosensors within a measurement range of wavelengths, and at least one reference range of wavelengths. Advantageously, the concentration of formaldehyde is determined taking into account fluctuations in the intensity of light emitted by the light source, and in the presence of any interferents such as nitrogen dioxide. A method of measuring the concentration of formaldehyde in enclosed environments is also presented.

Abstract: An optical absorption gas sensor comprising a body having an internal wall which defines a chamber, at least one aperture in the body through which a gas sample can enter the chamber, a light source, at least one reflector, a detector assembly which extends into the chamber and has a first side and an opposite second side, a detector which measures light which is incident at least a range of angles on at least a part of a first surface of the detector assembly on the first side of the detector assembly, wherein the light source is located within the chamber on the second side of the detector assembly, the whole being configured such that light from the light source passes through the gas sample and is reflected around the detector assembly, by the at least one reflector, onto the detector.

Abstract: A flue gas analyser for measuring the concentration of oxygen in flue gas, comprising an electrochemical oxygen sensor and water vapour removing means for reducing the relative humidity of received gas and/or nitrogen-containing-gas removing means for removing from received gas one or more gaseous species comprising nitrogen and oxygen which are either nitrogen dioxide, or formed from nitrogen dioxide in the presence of sufficient water vapour, which would otherwise lead to damage of the electrochemical oxygen sensor,

Abstract: A dual gas sensor is described, having first and second working electrodes separated by a gas impermeable portion. The electrodes are preferably located on a gas permeable polymer support, with the gas impermeable portion being formed by compression of the permeable support. The sensor may also include one or more filters for location adjacent the electrodes to filter certain gases from the air. The preferred sensor is able to detect carbon monoxide and hydrogen sulfide. The sensor housing is formed with four connection pins, allowing a standard sensor housing to be used for dual sensors as well as single sensors having a dummy pin.

Abstract: A fuel gas analyzer for measuring the concentration of oxygen in fuel gas, comprising an electrochemical oxygen sensor and water vapor removing means for reducing the relative humidity of received gas and/or nitrogen-containing-gas removing means for removing from received gas one or more gaseous species comprising nitrogen and oxygen which are either nitrogen dioxide, or formed from nitrogen dioxide in the presence of sufficient water vapor, which would otherwise lead to damage of the electrochemical oxygen sensor,

Abstract: An optical absorption gas sensor comprising a body having an internal wall which defines a chamber, at least one aperture in the body through which a gas sample can enter the chamber, a light source, at least one reflector, a detector assembly which extends into the chamber and has a first side and an opposite second side, a detector which measures light which is incident at at least a range of angles on at least a part of a first surface of the detector assembly on the first side of the detector assembly, wherein the light source is located within the chamber on the second side of the detector assembly, the whole being configured such that light from the light source passes through the gas sample and is reflected around the detector assembly, by the at least one reflector, onto the detector.

Abstract: Disclosed is an electrochemical sensor for measuring carbon monoxide in a gas sample, the sensor comprising a working electrode including a working electrode catalyst, and a diffusion restriction means for restricting the diffusion of the gas sample to the working electrode; wherein the working electrode catalyst comprises oxidised platinum having a hydrogen cross-sensitivity of less than 10% and being present in an amount such that the activity capacity is at least 5.

Abstract: Disclosed is a gas permeable electrode comprising an electrocatalyst which is permeable to a reactant or reaction product, the electrocatalyst comprising particulate boron-doped diamond. There is also disclosed a method of making an electrocatalyst which is permeable to a reactant or reaction product, the method comprising the step of forming an electrocatalyst comprising particulate boron-doped diamond.

Abstract: A dual gas sensor is described, having first and second working electrodes separated by a gas impermeable portion. The electrodes are preferably located on a gas permeable polymer support, with the gas impermeable portion being formed by compression of the permeable support. The sensor may also include one or more filters for location adjacent the electrodes to filter certain gases from the air. The preferred sensor is able to detect carbon monoxide and hydrogen sulfide. The sensor housing is formed with four connection pins, allowing a standard sensor housing to be used for dual sensors as well as single sensors having a dummy pin.

Abstract: An electrochemical gas sensor comprises: a working electrode for exposure to a gas to be sensed; a counter electrode having an outer periphery; a reservoir for electrolyte; wick means providing a path for electrolyte to pass from the reservoir, around a first part or parts of the outer periphery of the counter electrode to provide electrolytic continuity between the counter electrode and the working electrode; and a gas diffusion means providing a path for gas to diffuse to or from a second part or parts of the outer periphery of the counter electrode.

Abstract: Electrochemical sensor for determining analyte in the presence of interferent, particularly carbon monoxide in the presence of hydrogen. An electrochemical cell is designed so that current flow resulting from reference electrode potential shift caused by interferent cancels out the current flow caused by interferent at the working electrode. Another electrochemical cell corrects for interferent concentration using the potential difference between a reference electrode in contact with interferent and a referent electrode not affected by inteferent.

Abstract: A gas sensor comprising an electrolytic cell having detecting and reference electrodes connected by a solid electrolyte. In a first embodiment, both electrodes comprise Ag2CO3 and Ag4RbI5, and the electrolyte is Ag4RbI5, the reference electrode being in contact with a reference gas. In a second embodiment, the reference electrode is a silver electrode and no reference gas is needed. The sensor is operable at room temperature to measure CO2 concentrations, and is relatively unaffected by water vapor.