Method for liquid chromatography
US4422942A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 9, 1981 |
| Grant date | Dec 27, 1983 |
| Priority date | — |
| Expiry date | Sep 9, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2030/326
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
To stabilize flow rate in a single-stroke, syringe-type high pressure pump to a constant value after turn-on, a control system increases the pump speed until equilibrium conditions are reached and then pumps at the preset rate. In one embodiment, the control system senses the maximum rate of change of pressure, detects a pressure when the rate of change is two-thirds of the maximum, increases the pump rate until the pressure is three times that at the value of the detected pressure and begins pumping at the preset constant flow rate. In other embodiments: (1) a pumping system is operated at a flow rate ten times the preset flow rate and, when the time derivative of the pressure has dropped to nine tenths of its maximum, the pump motor speed is reduced to the preset flow rate; (2) the outflow of the column is measured under no load conditions at the desired flow rate and when a column is connected, the pumping speed is increased until the same outflow results before reducing the pumping rate; and (3) the system is operated in a constant pressure mode to a point at which the pressure is estimated to provide the desired flow rate, the flow rate measured, and if the flow rate is not th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.