pump impeller 1

[158728]

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?

 

[BigInch]

Wouldn't you have to reverse the facing direction; front face to back, back to front, so that's doubtful.

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

"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

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[Artisi]

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.

 

[JJPellin]

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

 

[BigInch]

Maybe you could do it in Australia.

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

"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

 

[ccfowler]

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.

 

[Artisi]

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.

 

[BigInch]

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." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

 

[Artisi]

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 .

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

 

[JJPellin]

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

 

[TenPenny]

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.

 

[SNORGY]

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.

 

[Artisi]

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

 

[daveboy]

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.