Abstract: A planar palladium structure makes use of the unique properties of palladium to provide a hydrogen permeable membrane suitable for use in providing, for example, selective control of a nominal gas pressure within a cavity. The contemplated planar palladium structure includes a planar substrate having upper and lower major surfaces and an array of microfine channels therebetween, wherein the channels allow gaseous communication between the upper and lower major surfaces, and an array of palladium deposits being distributed on the substrate and located with respect to the microfine channels so as to restrict the gaseous communication to diffusion of hydrogen gas.

Abstract: A method and apparatus for correcting flow and pressure sensor drift in a gas chromatograph. At a convenient time when the chromatograph is not being used for analysis, the input valves controlling the input into the chromatograph are shut, reducing internal flow to zero. The indicated rate of flow is then measured using the flow sensor. If the value measured by the flow sensor during this test is different than the originally calibrated offset by some predetermined amount, then the newly measured value replaces the stored offset value. In a chromatograph where some minimum internal gas or liquid flow is necessary to prevent contamination of the instrument, a three-way valve can direct liquid or gas flow away from the flow sensor during this calibration run without eliminating internal flow through the chromatograph. To calibrate the pressure sensor, the pressure sensor is vented to ambient air pressure and its reading at that pressure is then used as an offset during later sample analysis.

Abstract: In the preferred embodiment, the invention is embodied in the pneumatic manifold of a gas chromatograph to provide current operating temperature and pressure compensation of inlet fluid flow. The pneumatic manifold comprises a plurality of thermally coupled mass flow, pressure and temperature sensors which generate signals related to mass flow of the fluid, fluid pressure and sensor temperature prior to the introduction of the fluid into the column. A plurality of firmware models which characterize the effects of current operating temperature and pressure variations on the mass flow and pressure sensors are stored in computer memory.

Abstract: Methods and systems for determining the identity and flow rate of a fluid are provided. Linearized output signals are provided. To determine fluid flow, a test fluid is passed through a conduit. A heater associated with the conduit is maintained a temperature greater than the temperature of the conduit in the presence of the test fluid. A measuring voltage is generated, wherein the measuring voltage is indicative of the voltage required to maintain the heater at the specified temperature. A data set is provided to a computer, which compares the measuring voltage with a reference voltage and determines the identity of the test fluid. Further, a flow function is applied to the data set and the fluid flow rate is calculated.