Water Content Analysis

Method Karl Fischer Coulometric Autotitrator
Standards ASTM D 6304

What is it used for?

To quantify the amount of water present in a given sample, typically more suited to low level analysis on samples such as transformer oils, compressor oils and fuels.


How does it work?

A known weight of an oil sample is placed in a reaction cell with a portion of solvent using an auto-pipette and an analytical balance.


The main compartment of the titration cell contains the an alcohol-based anode solution including iodine and a base, plus a small amount of the sample. As a current is applied, Iodine is generated which consumes any water present.


The quantity of reagent needed to counteract the water in the oil is then used against the weight of oil added to determine the quantity of water in the sample.


What do the results tell us?

How much water is present within a given sample, whether it’s free, dissolved or emulsified.


This is key, as water is possibly the single most destructive contaminant commonly found in used (or sometimes unused) oil.


There are many paths for water to get into oil, which may include:


Poor storage

Environment (product ingress, clean-downs, humidity, etc.)


Coolant contamination

Leaking seals and filler caps

Assuming that using sight glasses to drain off free water is sufficient, leaving emulsified and dissolved water behind.


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