Dean-Stark and Karl Fisher Lab

I know one company which supplies these apparatus , Both Karl-Fisher and Dean-Stark, as follows: Petroleum Instruments (India) Pvt Ltd,Email id pil-india@sify.com and Fax 91-33-26831041.
Anybody who answers my following queries will be most welcome by many who like me want to add to their knowledge
Water may be present in any hydraulic oil in 3 forms, dissolved water, emulsified water and Free water,what is the minimum ppm at which the emulsification starts and at what ppm the water starts separating out as Free water. Of course it must vary from oil to oil, but still there must be some average value.
What is the lowest ppm that can be determined by Karl- Fischer or Dean-Stark methods.

Some fluids (like Castrol Subsea products) can hold up to 2000-3000 ppm (or more) before moving over to free water while som insulating oils are saturated at 40ppm. Usually oils that will work in moist enviroments will hold more moisture (like thruster oils).

The fases are also tied up to the fluids temperature.

Hughes,
You have missed the emulsification phase, and have not mentioned anything about it. I knew that I would not get concrete reply to my qustion.Let us be more specific, Take the case of Hydraulic oil with a viscosity of 68 at 40 oC, now tell the minimum ppm where emulsification will start and the minimum ppm after which water will separate out as Free water, Now don't tell me that it will depend from m/c to m/c, let us assume that we have kept the oil in laboratory at a temperature of 40 oC

Prabhakar.

I dont think I know the answer. I have tried to test with a %Sat meter(Pall WS04) and KF Coloumeter on a thin ISO VG15 oil. The oil was also tested on a particle analysis instrument (that detects droplets of water, and recognizes them)

We got water content at 100-150ppm = approx. 40-50% Saturated
300+/- ppm = >99% Saturated

(% Sat At 20 deg C - %Sat will drop when temp increases. Instrument confirmed by testing with a Hydac instrument)

I would claim that the oil had emulsified water from 50%Sat-99%Sat(150-300ppm). At this stage the particle instrument detects water droplets up to 30-40µm.

We have analysed 80-90 samples of this type (Same oil type). I must also note that the oil is used for flushing hydraulic systems (all over Europe) and any water was usually from contamination in components.

Not sure if my "research" helps you. I would recommend doing some testing yourself if you have the possibilities.

Hughes,
Thanks, you have given some valuable information based on facts arrived at during your research.But I want some more information. You have limited your experiment for water in dissolved condition which starts getting emulsified at approximately 150ppm, now do you have any exprience of saturation in emulsification stage when free water starts separating out.
At one place,I encountered Hydraulic oil 68 which was milky white, the oil was allowed to settle down for considerably long period, but no water was found at the bottom of the barrel even after 72 hours.Room temperature being around 30 degree centigrade. What should be the maximum percentage or ppm of water in such oil, any idea? At that place I had no equipment to find out the percentage of water.They asked me to guess, i reluctantly said it should be about 4%, how much right I was, of course I should not have expressed the figure.

Prabhakar,
I can not talk about a formal research. However I work some with a case in one of our customers. As Mr. Hughes said before the saturation point of oils vary from one type to other. We found products capables to hold up to 2500 ppm of water in disolve stage, and other showing free water with only 185 ppm. To capture this data we use Hydac Aqua Sensor and the Vaisal Humidity Sensor. We also tried to find the saturation charts from oil manufacturers, but it look like there is no interest.
Emulsions are a diferet story. The reason: there is "heavy" chemistry involved. Chemistry from the bases, aditives and contaminants (in used oils).
I don´t know if someone else perform more detailed studies in this field. For sure there still are a lot of things to discover.