Method and apparatus of conductivity measurement
US5504430A · kind A · utility
Inventor
Key dates
| Filing date | Jun 29, 1994 |
| Grant date | Apr 2, 1996 |
| Priority date | — |
| Expiry date | Jun 29, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2030/645
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention relates to a method for measuring conductivity, in particular for use in liquid chromatography systems, and to a device for performing such measurement. In one aspect it provides a method of measuring conductivity in liquids, comprising applying an AC voltage over a conductivity measurement cell. In response to a conductance value calculated from the output of the cell, an expected frequency of the AC voltage is generated. The AC voltage frequency is set to the calculated value. The above steps are repeated until two consecutive conductance determinations differ by only a predetermined absolute value. Then the value may be displayed and registered as the true conductance value of the sample. In another aspect it provides a device for measuring conductivity in liquids, comprising a conductivity measurement cell; AC voltage means for supplying a variable AC voltage across the cell; an operational amplifier having one input connected to the AC voltage means, and the other input to the cell; an AC/DC converter connected to the output of the operational amplifier; an A/D converter connected to the output of the AC/DC converter, the output of the A/D converter being…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.