Abstract: An electrochemical gas sensor having a relatively small sensing electrode (12) formed from powdered metal pressed onto a relatively thick porous sheet (24) of polytetrafluoroethylene (PTFE), through which gas is diffused. The electrode (12) is located at one end of a housing (10) containing an electrolyte (22) and a counter electrode (14). The sensing electrode structure provides relative insensitivity to temperature changes, rapid response to pressure charges, and a desirably low operating current.

Abstract: A device for emitting a gas at a constant rate into a moving fluid medium to produce an accurately known concentration of the gas in the medium. The gas is held in a cylinder (10) in which there are two chambers (14 and 16), one for holding the substance in liquefied form and the other for holding it solely in gaseous form. The substance permeates through a permeable material (20) between the two chambers and then through another quantity of permeable material (12) positioned at an exit from the second chamber (16). The device combines low temperature sensitivity associated with gaseous phase devices, and high permeation rates and lone useful lives associated with liquid phase devices. It is also safer than prior devices of the same general type.