Combustible-gas measuring instrument
US6812708B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jun 4, 2003 |
| Grant date | Nov 2, 2004 |
| Priority date | — |
| Expiry date | Jun 4, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/16
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A gas detection sensor system including active and reference elements (Rsense, Rref) are arranged in a modified bridge circuit (12, 14, 22, 24) which allows power (Vbat) to be supplied seperately to the active and reference element (Rsense, Rref). A digal processor (30) monitors the resistances of the elements (Rsense, Rref) to control a pulse-width modulator supplying power to the elements, thereby maintaining nearly constant temperatures in the sensor elements (Rsense, Rref) and to translate the decrease in power needed to maintain constant temperature on the catalytic element into an output proportional to the concentration of combutible gas in air. The system periodically measures the resistance of the elements (Rref, Rsense) and enables dual operating modes of catalytic-bead detector. One active or reference element (Rsense, Rref) can alternately measure low concentrations of combustible gases up to the lower explosive limit (LEL) or measure high concentrations, up to 100% by volume.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.