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Capacative Measuring Technology
Some items are not yet translated in English.Capacative Measuring Technology |
Every electrically charged material is surrounded by an electric field. Electric field lines from positive to negative are formed between materials with different charges. |
Two differently charged metal plates isolated from one another form a condenser. |
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Principles of the Condenser |
The principle of capacitive level measurement is based on the change in the capacity of a condenser caused by a change in the level. The capacity of a condenser is determined by means of 3 factors: |
Gap between electrode surfaces (d) |
Size of electrode surfaces (A) |
Dielectric between the electrodes (eI) |
Electric field constant |
8.854*10-12 C/(Vm) |
Dielectric constant (medium) |
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Dielectric Constants |
Dolomite Iron oxide Grain Broken glass Coffee Lime hydrate Lime powder Coal, raw Powdered coal Fodder concentrate Flour Nylon granulate Quartz powder Rice Sand, dry Washing powder |
Air = 1 |
Alcohol Petrol Chloroform Desmophen 5100 Desmodur 44 V Deuterium Liquid gases - Chlorine - Air -140°C - Butane - Propane Glycerine Heating oil Latex Petroleum Water |
Some items are not yet translated in English.
Electric Conductivity |
Non-conductive media |
(hydrocarbons, solvents, petrols, oils) |
Low-conductive media |
(hydrocarbons with a higher water content, demineralised water) |
The DK of the medium must not change through moisture, for example. Otherwise, the level can no longer be reliably measured. |
The measuring flow not only depends on the DK, but also on the conductivity of the medium. |
Conductive media |
(aqueous solutions of salts, acids, alkalis, electrolytes, food, beverages) |
A change in the DK and conductivity does not have any effect on capacity since the medium produces a short circuit with the container wall. |
Para más información: Endress+Hauser GmbH