Abstract: An apparatus detects a target gas in ambient air. The apparatus has a GC column, a sensor downstream of the GC column, a pump, a gas storage chamber and a pneumatic circuit. The pneumatic circuit has two states. In a first state, the pump draws in ambient air and supplies it to the gas storage chamber to store ambient air under pressure within the chamber, while trapping a sample of ambient air within the pneumatic circuit. In the second state, the gas storage chamber is connected to the GC column to cause pressurised air drawn from the storage chamber to act as a carrier gas to advance the trapped sample through the GC column and sensor. A filter is filters out any target gas present in the air entering into, or the air drawn from, the storage chamber, to avoid the presence of any target gas in the carrier gas.

Abstract: An apparatus for detecting the presence of gaseous analytes in water includes a submersible housing enclosing a water proof sensing chamber having a first wall made of a material transparent to UV light and a second wall formed by a gas permeable membrane for admitting into the sensing chamber gas dissolved in water in which the housing is immersed during operation, a first and a second spaced sensing electrodes disposed within the sensing chamber, and a circuit connected to the sensing electrodes for measuring a current flowing through the sensing electrodes on account of ionization of a gas in the sensing chamber by UV light. A third electrode is positioned in the sensing chamber, and the circuit is operative to apply a voltage across the third electrode and the first sensing electrode, the voltage being of sufficient magnitude to reduce condensation within the sensing chamber by hydrolyzing any droplet of condensation in electrical contact with the first and third electrodes.

Abstract: A pneumatic manifold which can be constructed using standard PCB (Printed Circuit Board) construction techniques provides customised flow distribution around (and/or between) different members. By virtue of its PCB construction the manifold also may include conductive electrical tracks and fixing points common to other PCBs and possibly serving electrical pneumatic components.

Abstract: A hydrogen generator includes at least two electrolytic cells, each comprising a membrane electrode assembly incorporating a solid polymer electrolyte. The membrane electrode of a first cell is exposed to water and the hydrogen produced in this cell contacts the cathode surfaces of the successive electrolytic cells, wherein any water entrained in or carried over with the hydrogen produced in the first cell is the only significant feedstock for the successive electrolytic cells. In some embodiments, the first and second cells share a common chamber enclosing the respective electrodes. Hydrogen generated by the first cell diffuses into an expanded polytetrafluoroethylene tube adjacent to the cathode. The tube discharges into a space abutting the cathode of the second cell.

Abstract: A demountable pellet is disclosed for use as an electrode contact assembly. The pellet comprises a base 1 upon which is mounted a plurality of electrodes 18, 19, 20 arranged in respective spaced parallel planes and having respective contacts 23, 24, 25 protruding from them. A closure 2 for the base 1 has a member 11, 12, 13 engaging at least one of the electrode contacts. In an unassembled condition of the pellet, with the closure 2 separate from the base 1 and each closure member disengaged from its respective electrode contact, the contacts 23, 24, 25 lie in respective spaced parallel planes. In the assembled condition of the pellet with each closure member engaging its respective electrode contact, at least one of the contacts 23, 24, 25 lies in a plane other than that in which it lay in the unassembled condition of the pellet.

Abstract: A demountable pellet is disclosed for use as an electrode contact assembly. The pellet comprises a base 1 upon which is mounted a plurality of electrodes 18, 19, 20 arranged in respective spaced parallel planes and having respective contacts 23, 24, 25 protruding from them. A closure 2 for the base 1 has a member 11, 12, 13 engaging at least one of the electrode contacts. In an unassembled condition of the pellet, with the closure 2 separate from the base 1 and each closure member disengaged from its respective electrode contact, the contacts 23, 24, 25 lie in respective spaced parallel planes. In the assembled condition of the pellet with each closure member engaging its respective electrode contact, at least one of the contacts 23, 24, 25 lies in a plane other than that in which it lay in the unassembled condition of the pellet.

Abstract: An ionization detector includes a third (fence) electrode (55) between the counter electrode (53) and the sensing electrode (54). The fence electrode (53) is maintained at or near the potential of the sensing electrode (54) and traps charge movement (electrolytic current) along the detector walls associated with condensation and/or contamination within the detector. In a photoionisation detector, the fence electrode is also adapted to trap photo-induced current originating from the cathode (53). Current drawn from the fence electrode (53) provides a measure of the degree of contamination or condensation within the detector and of lamp efficiency.

Abstract: The present invention provides a hydrogen collector and detector system for detecting emanating hydrogen from the test surface of materials, a hydrogen collector for use in such a system and a method for using the hydrogen collector in such a system. The present collector comprises a flexible plate, which has constructed on its receptor face raised grooves or high spots. These are presented approximately parallel to an approximately flat test surface or approximately tangential to a curved test surface, and form guiding channels along which hydrogen emanating from the test surface can be drawn and sent to an associated detector system. For use on a magnetizable surface, the present collector plate may comprise magnets by which it can firmly yet removably be attached to the test surface.