Apparatus for controlling a pump to account for compressibility of liquids in obtaining steady flow
US4797207A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 1986 |
| Grant date | Jan 10, 1989 |
| Priority date | — |
| Expiry date | Sep 30, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2030/326
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
There is disclosed herein an apparatus and method for controlling a dual piston pump for a liquid chromatography system so as to pump a flow of solvent through the liquid chromatography column at a constant flow rate and with a solvent composition which is substantially equal to the desired solvent composition despite changing conditions of compressibility of the solvent. The control system uses a computer which measures the time it takes the pump shaft to move through an overlap region in the pump cycle when both pistons are simultaneously pumping as normalized to the time taken by the pump to move through a constant velocity portion of the piston travel defined by the user. This time is compared to the time stored in the computer for the particular flow rate used to measure the time defined above for the pump to move through the overlap region for an incompressible solvent at low pressure as normalized to the time taken by the input piston to move through the same user defined segment of the constant velocity portion of the travel of the input piston. The ratio of these two times is then used in an algorithm to derive a correction factor for compressibility. This correction facto…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.