Method and apparatus for correcting flow and pressure sensor drift in a gas chromatograph
US5542286A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 23, 1995 |
| Grant date | Aug 6, 1996 |
| Priority date | — |
| Expiry date | Jan 23, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N30/32
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.