Can anyone offer information or experiences in working with water based hydraulic oil in a foundary application. What are the normal problems associated with keeping this lubricant in peak performance parameters. How does the water based oil perform once contaminated with dirt and additional water ?

What level of water would be considered high and "out of operating limits"

I would recommend reading theese bulletins from an Australian company (Oiltech):
http://www.oiltech.com.au

Hello Mr Hughes,

I appreciate the informative link

Thank you kindly

In water Glycol based hydraulic fluids ,excesive water content can lead to reduction of viscosity / film thickness and lead to wear of hydraulic components .Increase in water also drops the pH which might help microscopic organisms to thrive and thus leading to corroison problems.

The water content that tends to drop the viscosity by 10% should be the warning limit and by 15-20 % should be the rejection limit.

This based on our experience with water-glycol fluids. Your views on this are welcome.

Craig, I work in a steel mill where most all our hydraulic systems use water glycol. We sample the fluid monthly checking the particulates and water content. Our blend is 40% water and if we have a problem with the water it is usually where the water content has evaporated due to high temp. The only time I've ever had too high water content was with a faulty heat exchanger. All our pumps are derated to 1200RPM instead of the 1800 that is used with most mineral oil applications and most all the systems are 2200 PSI or less operating pressure. The reliability of the hydraulic systems is fairly good although the life of the componets is somewhat shortened.Tom wilson