Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Alternative to hydraulic oil in air over oil system

Alternative to hydraulic oil in air over oil system

Alternative to hydraulic oil in air over oil system

I'm reading a specification from an OEM that manufactures automotive lifts, and they say for air/oil systems NOT to use hydraulic oil as it can foam under air pressure. They then give some properties for a fluid that appear very similar to AW32 oil. Would anyone have any inclination about a possible alternative here?

RE: Alternative to hydraulic oil in air over oil system

a aw32 oil suggests a thin (32 mm2/s) oil that contains some form of antiwear additive, usually zinc based. that could also be considered to be a low viscous hydraulic oil...hydraulic oils are usually formulated in such a way that they have good air release properties - you do not want air bubbles entrained in a pressurized fluid, whereas a small amount of foam on top of the fluid in a nonpressurized reservoir does not pose a problem as long as the pump is fed from a region within the reservoir where no foam is available. foaming within hydraulic systems most times is caused by either dirt that kills the air release properties of the fluid or by design faults in the hydraulic system ("splashy" return line or to a too small volume of the reservoir, so no complete air release is possible. in theory the foaming tendency can be decreased by adding a small amount of antifoaming agent (a few ppm!) but usually that increases the air release time quite a bit and thus causing a bigger problem then the problem solved....

steam turbine oils are known for their excellent air release properties and very low foaming tendency. thus, a ISO VG 32 steam turbine oil might be a alternative, as long as no antiwear properties are expressly required.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close