Honeywell Normalair-garrett (holdings) Limited

Peter Hedges

A method of controlling an apparatus for separating product gas and non product gas from an air supply, the concentration of the product gas produced by the apparatus being variable depending on a control signal from a controller and the efficiency of the apparatus in producing product gas depending upon an environmental parameter, the method including sensing the oxygen concentration in the product gas produced by the apparatus, determining an instantaneous demand for oxygen concentration in the product gas, providing to the controller a process variable signal indicative of the sensed concentration of the oxygen in the product gas, and providing to the controller a demand input signal indicative of the demand, sensing the environmental parameter and providing an environmental parameter input signal to the controller, comparing the process variable signal and the demand signal to generate an error signal indicative of a change in oxygen concentration in the product gas required to match the instantaneous demand, conditioning the error signal to derive a control signal to control the apparatus to satisfy the demand, characterised in that the conditioning of the error signal is compensated to derive the control signal, depending upon the environmental parameter input signal.

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Dorchester, United Kingdom

Peter Hedges