Abstract: A method and device for determining the end point for drying in a stream of flowing fluid which method utilizes a reduction in pressure to effect a bypass of fluid flow through a humidity sensor with return of the sample to the main fluid stream. The method is accomplished by placing a first conduit member with the orifice in a nonconfronting manner with respect to the flow and a second conduit member also in the main channel and spaced from the first conduit. A pressure differential is effected between the orifices so as to effect flow through the first orifice to the sensing device and out through the second orifice. In a preferred manner, a pressure differential is effected by utilizing a larger orifice for the second conduit and positioning both orifices opposite the stream flow. A preferred apparatus for effecting the method utilizes a tubular or pipe member for the first conduit which has a curved portion to present an orifice opposite the flow of fluid.