Pump Impeller Spin Test : How do we do it ? What is its purpose? 1

[Tilas]

Hi,

I am currently going to modify an existing pump to enhance its process capabilities (increased impeller diameter).
There is a requirement from Client for a "Spin Test" for the impeller.

Can anyone enlighten me on what does a spin test for an impeller is for and how do we normally do it.

I suppose that it is not the same as impeller balancing.

Thanks in advance

 

[LittleInch]

B it difficult without knowing all the details, but if this is for a pump which has been removed from its frame, then my guess is that it is a spin test to make sure the pump is going round the right way.

normally done by "flicking" the motor on then immediately off and watching the rotation of the shaft, so it might need the shaft guards or coupling guards to see clearly which direction it goes.

I might be wrong and its a pump thing, but if that fits in then give it a try.

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

 

[1gibson]

My guess, it is a "spin down" test. After the performance test you kill the motor and watch the shaft as the pump slows down to a stop. You want to see a smooth, consistent reduction in speed. If there is any shuddering or an abrupt stop, the pump has a rub that should be investigated. If the performance test is not witnessed by the client, you could always take a video of the shaft/coupling starting when the motor is turned off.

 

[bimr]

For shaft driven deep well pumps, a spin test is used to demonstrate satisfactory operation of bearing clearances, wear rings and sealing arrangements.

 

[Artisi]

A fairly useless specification, ask the client what they mean by spin-test.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

Tilas -

If artisi doesn't know then it's not a known thing in the pump world.

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

 

[Artisi]

You could take it literally and run the pump, do you do it wet or dry, for how long at what speed??????

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Tilas]

Hi Guys,

Thanks for the inputs.As additional info, i will only purchase a new impeller and install it on the old pump.I have given all the requirements for the impeller like balancing requirement,NDE requirement etc but spin test was requested by Client for the impeller alone.Would ask Client what he really mean about this test.Just want to get some inputs prior to talking to him.

From the web i've seen some explanation of spinning the impeller to 115% of its rated speed :

http://www.piller-tsc.com/index.php?id=11

I just dont know if i can really apply this to my impeller and if it really has its merit.

 

[JJPellin]

We have required a spin test following weld repairs of large impellers. It involved spinning the impeller to a speed above maximum operating speed to verify structural integrity. It is done in a test rig (dry). It is not common and not normally required for new impellers. Is this impeller extremely large or extremely high speed?

Johnny Pellin

 

[Tilas]

Thanks JJpellin,

The pump is small around 370 kW and the speed is only 1500 rpm.

So this means that "spin test" can also apply even if my pump is in a constant speed? Even if it not suppose to run at any other speed higher than that? Or it can only be applied for those impellers which runs on variable speed like compressors and turbines?

Thanks
Kristian

 

[Artisi]

Have you yet asked the client why or what they expect to achieve?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)