×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

Air Pocket issue on pump suction

Air Pocket issue on pump suction

Air Pocket issue on pump suction

(OP)
Hi All

Rail car tankers are connected to pipework via 4" hose. This is to transfer fuel to the terminal fuel storage.
Unfortunately, inherent in the original design, after the NRV and valve, it step up to a 6" pipework.
A short pipework before the pump suction of the same 6".

There always seems a built up of air in the pipe suction.
Possibly carried over by the air bubble (?) through the system.
There is a vent just before the pump suction. The operator have to bleed the air several times throughout the pumping process to reduce air lock and increase transfer rate.
Is there a device or simple setup to remove the trap air on the SUCTION side.

(orifice is not an option in this case).



Thanks in advance

RE: Air Pocket issue on pump suction

You have a spring closed check valve on the suction inside of the pump. Your pump is likely struggling to prime against the check. Self-priming pumps will always struggle to prime against check valves and should have bypasses.

RE: Air Pocket issue on pump suction

What is the orientation of the reducer at the pump suction - can you post a phot of that?

Pump suctions should be top flat if you've got a reducer there.

The issue with any auto air vent is that often the pressure in the pie is less than atmospheric in operation as the pump draws down the pressure to get flow from the rail cars, or maybe starts off positive then goes negative. The only option then is to rig up a float system with a vacuum line on top to suck out the air / vapour.

Is that NRV a spring loaded NRV or not?

Off loading systems like this often suffer from vapour being released from the fluid - what is it?, what temperature and now close are you to the vapour pressure of the fluid. If this is gasoline you're basically cavitating the pump is my guess.

Your best bet long term is to either lower the pump or use a can pump.

But first either observe from the suction guage or calculate what the inlet pressure is right before the pump when the tankers are at high level AND low level. If you don't have a suction guage, fit one.

Then give us the FULL picture and we might be able to help some more.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Air Pocket issue on pump suction

Maybe butane, propane or LPG are especially problematic.

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

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. 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