Abstract: The invention relates to monitoring equipment for smoke and/or fine particle emissions from fossil fuel systems, of the type where a beam of visible light is passed across a flue from a light source to a detector, a difference in the light intensity received by the detector from the known intensity of the source indicating absorption of light by smoke and/or fine particles in the flue, and the degree of difference indicating the level of smoke and/or fine particles. The objective of the invention is to provide monitoring equipment of the above type, of simpler, lower cost, more robust nature than has hitherto been provided. The objective is met by a construction comprising two units (1, 2) for location of opposite sides of a flue or chimney each unit comprising a light source, (L.sub.1, L.sub.2) a lens (4) and a light detector (D.sub.1, D.sub.

Abstract: A method of monitoring a selected flame in a multi-burner furnace comprises positioning two arrays of photoelectric sensors, providing an optical path for the sensors of each array so that the line of sight of one sensor of one array will intersect the line of sight of one sensor of the other array, electronically scanning the two arrays to determine the sensors, one from each array, which give maximum correlation of output signals from the sensors to electronically optimize the signals generated from selected sensors, and electronically locking on to the selected sensors to monitor the selected flame.

Abstract: The invention relates to gas monitoring. Hitherto gas, such as flue gas has been analysed either by sampling and analysing the sample or by a spectrometer. However sampling is unreliable, and spectrography involves sensitive and expensive equipment needing extensive protection against vibration. In the invention, gas is monitored in situ by providing an infra red source and an infra red detector spaced across a gas flow, with a filter cell filled with the gas component to be monitored disposed between them. The detector detects radiation direct from the source and passing through the filter cell, and the outputs from the detector are fed to a differencing and dividing circuit to provide an output that is a function of the amount of monitored gas component in the gas flow.

Abstract: A dewpointmeter comprises a detecting element or probe, a thermocouple adapted to determine the temperature of the probe, means for directing a flow of cooling air at the probe, and an electrical circuit extending to the probe and adapted to be completed by condensate formed on the probe, there being a motor driven regulator adapted to control the rate of flow of cooling air directed at the probe, which motor is adapted to be driven in accordance with the current flowing through the circuit.