Measuring and testing – Instrument proving or calibrating – Gas or liquid analyzer
Patent
1998-12-07
2000-06-20
Raevis, Robert
Measuring and testing
Instrument proving or calibrating
Gas or liquid analyzer
G01N 100
Patent
active
060763906
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a method for calibration of an analysis system having a diaphragm, the outside of which is immersed into a medium to be analysed, and on the inside of which a carrier fluid for the admission of a species penetrating the diaphragm is flowing.
Further, the invention concerns an analysis system with a diaphragm, the outside of which is immersed into a medium to be analysed, by which a flow path is arranged on the inside of the diaphragm, the inlet side of which is connected to a reservoir of a carrier fluid and the outlet side of which is connected to a detector.
Such analysis systems are working with some sort of dialysis, i.e. the species to be analysed penetrates the diaphragm and thus reaches the carrier fluid. This penetration occurs for instance as diffusion. The species can for instance consist of ions or other low-molecular parts, which are contained in the fluid to be analysed, which is bearing against the outside of the diaphragm or flows past it.
It is known that such analysis systems must be calibrated at certain intervals. Such calibrations are at least always required, when a new diaphragm is used. Normally, the life of the diaphragms is limited. Though they are in principle the same, there are deviations from diaphragm to diaphragm, which can be taken into consideration by a calibration. Further, such diaphragms do in many cases turn out to have an ageing behaviour, meaning that their permeability to the species changes over the time. Also for this reason periodical calibrations are required, to determine a "transition factor" of the diaphragm. This transition factor permits a derivation of the actual quantity or concentration of the species in the medium to be analysed on the basis of the load of species in the carrier fluid.
Such calibrations can be carried through in the laboratory without problems, as the corresponding measurements can be made in a controlled environment. As, however, application on site of analysis systems is gaining importance, for instance swimming in settling tanks in sewage disposal plant or in outfall ditches, and the recovery for calibration purposes is too expensive, it has been endeavoured to find solutions for carrying through calibrations on site, i.e. in the installation in question.
In an analysis system known from DE 44 24 494 A1, calibration is thus made in that two different carrier fluids are led past the diaphragm, which carrier fluids differ from each other with respect to the concentration of the species to be detected. The starting concentration in both fluids is known. The concentration after passing the diaphragm can be measured. This gives sufficient information to determine the penetration behaviour or the transition factor, which can be called "efficiency". In subsequent measurements this efficiency can be used to conclude or calculate the concentration of the species in the medium to be analysed on the basis of the load of species in the carrier fluid.
However, with the known system it is necessary to have two different carrier fluids. Thus, space must be provided for the corresponding reservoirs and for the corresponding pump or any other sort of flow controlling device.
The task of the invention is to reduce the constructional expenses connected with the calibration.
With a method as mentioned in the introduction, this task is solved in that, in a calibration step, the carrier fluid is stopped on the inside of the diaphragm for a predetermined sojourn time, after which the load of the species in the carrier fluid is determined, in a further calibration step the carrier fluid is led past the diaphragm at a speed also used for measurements and the load of the species in the carrier fluid is determined, and the penetration behaviour of the diaphragm is determined on the basis of both load values.
When the carrier fluid remains inside the diaphragm for a long time, a balancing of the concentrations of species on both sides of the diaphragm will occur, meaning that the concentration of species in the carrier fluid has exactly t
REFERENCES:
patent: 4410211 (1983-10-01), Sugawara et al.
patent: 4942135 (1990-07-01), Zaromb
patent: 5448922 (1995-09-01), Kimbell et al.
Danfoss A/S
Raevis Robert
LandOfFree
Method for calibration of an analysis system and an analysis sys does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for calibration of an analysis system and an analysis sys, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for calibration of an analysis system and an analysis sys will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1842120