How to "Rebuild" a Pump Impellor

This past month I received a great question from the PNCWA Asset Management newsletter reader, which I am again going to post here.

Question: I have an old pump that has a very worn impellor including both holes through the blades and worn wear ring interfaces. The pump is scheduled for replacement on next year's Capital Plan, is there anything that can be done to "fix" the impellor for the short term? A new impellor would cost nearly as much as a replacement pump.

ANSWER: There is a way to temporarily or permanently fix both a casing and impellor of a pump. This is a great idea, and I have to give credit for this solution to Terry Nelson of inspiraworks.com. Two years ago Terry gave an entire presentation which he called Making Things Better. He presented a whole list of improvements that he has used over the years to repair and/or improve centrifugal pumps, including this tip.



Remove the impellor from the housing to gain full access to the surfaces. Using Chesterton ARC 858 epoxy putty smoothly coat and fill in all of the gaps and build up the edges as necessary. See product below:



http://www.chesterton.com/products/arc/product/?product=858

WARNING: make sure that you get the 858 shaped properly when it is wet. This product, while it appears to be a Bondo product gets extremely hard. During Terry's first experiment with the product, he wasn't too careful to smooth it when it was wet. He then spent two days and several grinder disks to get it shaped up.

Consider using this strategy even for a permanent repair to an old pump that an impellor would be difficult or impossible to purchase. It not only saves on the purchase of the pump itself, but all of the related construction/remodel work which might be necessary to replace an old pump with a newer design.

As an additional protection against wear, consider using the Chesterton 855 "paint" product (http://www.chesterton.com/products/arc/product/default.asp/product/855) as a surface coating, particularly for high abrasive applications. The "paint" comes in grey and black and if you applied two coats of one color over the other, you could easily remove an inspection port and observe with a flashlight how the impellor or casing is wearing.

Correctly applied, i.e. smooth, surfacing should increase the efficiency of your pump too, so you might even get a bit of a payback on your energy.

Let me know if you are interested in hearing about other ways to Make Things Better and I will see if I can get Terry to make the entire presentation available.