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h2osensorgb [2026/04/06 20:56] – [How does it work?] administratorh2osensorgb [2026/04/07 01:43] (aktuell) – [How does it work?] administrator
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 </figure> </figure>
  
-Each one of this conductive traces acts as an electrode with alternating polarity next to each other. By applying an electrical voltage to the electrodes the phosphoric acid, or better the amount of water it contains, is broken down via electrolysis.+Each one of this conductive traces acts as an electrode with alternating polarity next to each other. By applying an electrical voltage to the electrodes the phosphoric acid, or better the amount of water it contains, is broken down via electrolysis into oxygen and hydrogen ({{ref>scheme}}).(([[https://www.dks-engineering.com/de/wissen/spurenfeuchtemessung-definition-und-messprinzipien|Coulometrischer Feuchtesensor / Spurenfeuchtemessung, 06.04.2026 (external link)]]))
  
 <figure center|scheme> <figure center|scheme>
 {{:wartung:wassersensor:elektrolyse.drawio.png |}} {{:wartung:wassersensor:elektrolyse.drawio.png |}}
-<caption>Schematic display of the working principle of a phosphoric acid-based moisture sensor.</caption>+<caption>Schematic display of the working principle of a phosphoric acid-based moisture sensor. U is a voltage source and A is an ampere meter connected in series.</caption>
 </figure> </figure>
  
 +The electric current flowing in this electrolysis can be measured by using an ampere meter (A). According to the Faraday law the current **//I//** is proportional to the amount of substance **//n//** converted at the electrodes ({{ref>equation}}). This enables the possibility to determine the moisture in a system down to the ppm level.
  
 +
 +<figure center|equation>
 +{{:wartung:wassersensor:1775088659.png?direct&400 |title}}
 +<caption>The Faraday law rearranged towards the amount of substance //n//.</caption>
 +</figure>
 +
 +The probe head needs a constant flow of gas to work correctly. A standing atmosphere over the probe head will inherently dry itself and therefore provide false data.
 +
 +Basic gases and fumes will form phosphates with the phosphoric acid (e. g. amines). This leads to the deterioration of the acid which is the reason why the sensor head needs to be cleaned and impregnated with fresh acid on a regular basis.