Sensor for hand held gas chromatograph
US4787239A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 11, 1988 |
| Grant date | Nov 29, 1988 |
| Priority date | — |
| Expiry date | Jan 11, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N30/64
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A portable gas chromatographic detector includes two identical platinum coils mounted on identically aligned conducting posts. One coil is placed in an occluded chamber; the other coil is placed in an identical isolated chamber. Both coils have connection to legs of a bridge circuit and have substantially identical current flow passed along their length. Both chambers are preferably identically dimensioned and are large enough not to interfere with the field of the coils. The occluded chamber communicates through a short passageway with a passing classified gas stream from a chromatographic column. It has been found that the motion with respect to one coil is compensated with respect to the motion with the remaining coil so that the only differential in electrical resistance measured across the bridge circuit is that induced by the cooling property of helium on the heated coil in the occluded chamber. Cycling of the portable chromatograph includes a first short cycle. In the absence of detected helium, the instrument immediately returns to a standby state in readiness for a closely repeated cycle. Upon the detection of helium, a second and longer cycle results prolonged only by tha…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.