×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Pressure in a Oil Damper

Pressure in a Oil Damper

Pressure in a Oil Damper

(OP)
If I have a double rod-end cylinder, fill it with oil, and connect both ends together via a needle valve, then start applying force to the rod in order to push/pull the pistion, is there any pressure difference acorss the valve when the needle valve is fully open? If so how can I calculate it? Is the pressure independent from the applied force?

Thanks

RE: Pressure in a Oil Damper

Even if the needle valve is fully open you most likely still have some pressure drop, depending on the flow. Even with the valve open you have to consider the fittings, hose/line, needle valve body, etc. The pressure will be a function of flow and restriction. ISZ

RE: Pressure in a Oil Damper

You need to know the valve pressure/flow characteristics for various valve openings.  Calculate pressure drop vs flow rate.
Relate flow rate to piston speed.
Relate piston force to pressure.
Then you will know the relation of piston force to piston speed for various valve openings.

Ted

RE: Pressure in a Oil Damper

(OP)
Thanks Ted and ISZ.
OK there is pressure drop due to the valve structure, fittings, hose/line.
The problem is I want to choose a right valve for my system, and I do not know about my valve yet.
Let me ask my question this way: in an ideal (unrealistic)situation If there is no head loss across the valve due to the friction etc, is there any pressure difference between two ends of the cylinder when I am moving the piston?
Please note that there is no pump in the circuit and the system is totally passive (driving force is applied to the rod)

RE: Pressure in a Oil Damper

In your unrealistic case, very little.  Flow does move from high pressure to low pessure and with no flow losses this difference would be very small.  An ideal, frictionless condition.  Therefore, essentially no damping.

Ted

RE: Pressure in a Oil Damper

There may be inertial forces that so far are being neglected.  Acceleration of the fluid; acceleration of the piston.

Ted

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! Already a Member? Login


Resources

eBook - Integrating the Engineering Ecosystem
Aras Innovator provides multiple options for integrating data between systems, depending on the scenario. Utilizing the right approach to meet specific business requirements is vital. These needs range from authoring tools, federating data from various and dissimilar databases, and triggering processes and workflows. Download Now
White Paper - Industry 4.0 and the Future of Engineering Education
With industries becoming more automated, more tech-driven and more complex, engineers need to keep their skills and knowledge up to date in order to stay on top of this wave—and to be prepared for the Industry 4.0 future. The University of Cincinnati offers two online Master of Engineering degree programs designed specifically for practicing engineers. Download Now
eBook - The Design Gridlock Manifesto
In this eBook, you’ll learn 6 ways old CAD technology slows your company down and hear how design teams have put those problems to rest. “The Design Gridlock Manifesto” shares first-hand modern CAD experiences from 15 companies around the world. Download Now
White Paper - Comparing Multi-Patterning at 5nm: SADP, SAQP, and SALELE
Self-aligned multi-patterning techniques such as SADP, SAQP, and SALELE are increasingly popular at advanced nodes, but each process has its pros and cons. IMEC and Mentor, a Siemens business collaborated to identify potentially less-obvious process and design limitations and trade-offs between the three SAMP techniques. Learn more in this paper. Download Now

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