Water Separability or Demusibility

Method Physical Method
Standards ASTM D 1401

What is it used for?

In a lot of applications, the ability of a lubricant to resist emulsification and separate itself from water ingress in a key feature, particularly when subject to turbulence.


Poor water separability can lead to lubricant degradation, corrosion, cavitation and eventual mechanical failure.


How does it work?

An amount of both water and the lubricant to be tested are mixed under controlled conditions at a fixed speed.


40 ml of distilled water is gradually added to 40mL of heated oilf a graduated cylinder and stirred at 1,500 rpm for 5 minutes at constant temperature.  The contents are then left to separate at time intervals.


What do the results tell us?

How well the lubricant interacts - and separates from - moisture.


The three measurements for oil/water/unseparated emulsion are presented in that order separated by forward slashes. Test time in minutes are shown in brackets.


For example, a result of 35/35/10 (60) denotes 35mL oil layer, 35mL water layer and 10mL emulsion layer, with a test time of sixty minutes.


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