×
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

Jobs

pump impeller

pump impeller

pump impeller

(OP)

I have two centrifugal pumps working with different direction of rotation (one pump is left hand direction and the other is right hand direction).
is it possible to interchange the impellers of these two pumps by taking the impeller of the right hand pump and install it in the left hand pump? is the design of the impellers and the method of fixing them to the shaft the same?
 

RE: pump impeller

Depending how the impellers are mounted onto the shafts, it may be possible to interchange BUT DON'T expect them to work.
It seems fairly logical if one impeller rotates in a different directon to the other there must be a difference between them.

RE: pump impeller

In the vast majority of centrifugal pumps, these impellers could not be interchanged.  The only common configuration where this might be possible would be a double suction, between bearings pump with a key driven impeller.  For any other types that come to mind, the impeller is not symmetrical front to back (as BigInch suggests).  And, even if you could interchange the impellers, it would not work in other configurations (as Artisi points out) because the volutes or diffuser vanes would not be correct for the new rotation.  If you are desperate need of a replacement impeller, you better look somewhere else.   

Johnny Pellin

RE: pump impeller

If they are both true radial bladed wheels, it might work, but even then, there may be some dimensional issues.

The main question that I have is WHY?  Perhaps by providing more information, the basis of your question would be more apparent, and the advice available would be more useful to you.

Valuable advice from a professor many years ago:  First, design for graceful failure.  Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs.  Only then can practicality and economics be properly considered.

RE: pump impeller

BigInch - pumps can run upside down in Australia.

I did come across a problem of a non performing pump which turned out to be wrong handed impeller - didn't pump much and took quite awhile with a lot of head scratching to sort out what the problem was.

 

RE: pump impeller

Yes.  That would be hydraulically similar as a pump with a reversed wired motor.  They usually arn't the first item on the troubleshooting checklist, but you should find them somewhere on it.

I thought so. Thanks for confirming that they will run upside down.  I suppose its true for helicopters, trains, etc.
Spacelaunch pads???

"I am sure it can be done. I've seen it on the internet."  BigInch's favorite client.

"Being GREEN isn't easy." Kermitfrog http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

RE: pump impeller

That's the rub of course - you check direction of rotation of the pump and it's correct but still doesn't perform - so more head scratching until someone says - heah! we have two styles of pump in this configuration 1 runs clockwise and the other anti-clockwise - then the penny drops - so open the pump and check the impeller configuration banghead.

Yep it's marvelous how it all works upside down - but why do we still have NPSHa problems if the water is on top.

RE: pump impeller

We have seen incorrect impeller orientation many times. It (almost) only happens with between bearings, double suction pumps where they just put the impeller back on backwards.  There was one other case that still worries me.  Someone bought a Sundyne pump which uses straight radial vanes.  I had always been told that all Sundyne pumps use counter-clockwise impeller rotation (viewed from the drive end).  And, this person bought a Coppus turbine specified for CCW rotation. I have also been told that everything on a steam turbine (including rotation) was judged looking from the governor end to toward the coupling end.  Apparently, this statement is true of all steam turbine manufacturers except for Coppus.  Coppus determines rotation viewed from the coupling looking toward the governor.  When they went to put it together, they found that they had a CW turbine and CCW pump.  It was cheaper, faster and easier to reverse the orientation of the pump than the turbine. Since the impeller had straight radial vanes, it did not need to be changed.  So, they bought a special, custom made CW diffuser for the pump.  Based on recent conversations with a Sundyne engineer, we may have the only clockwise Sundyne pump ever made.

I guess the lesson of this example could be "never assume."

Johnny Pellin

RE: pump impeller

If it's a double suction/between bearings pump, and the two pumps are the same size/model, you can do it.  It's quite common to have a set with one CW and one CCW rotation, side by side.  I do not know of any double suction / bb / split case pump where the impellers are different for CW vs CCW rotation.

On some of these pumps, the shafts and sleeves are different if they are threaded on, as the threads are different directions, but the impellers are the same.  On others, there is no difference between the shafts and sleeves.

Take care, however, as it is really easy to get the impeller on backwards.  Make sure your shop knows which way you want the rotation to be, and look carefully (and document with pictures) how the assembly goes back together.

 

RE: pump impeller

What about a pump with a closed impeller that is symmetrical about a plane cut through it normal to its axis of rotation?  Then all you should need to do is install the impeller upside down.

It sounds a bit easier than what would otherwise be proposed in Australia.

Star for BigInch, by the way.

Regards,

SNORGY.

RE: pump impeller

TenPenny, split case / bb/ single suction inpeller CW and ACW models, taught me a never to forget lesson.    

RE: pump impeller

You need to take care on higher energy double suction impellers as there may be biased wear rings to ensure thrust is always in one direction therefore it only fits oneway to fit the mating parts.

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!


Resources