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options for sealing shafts against water entry
6

options for sealing shafts against water entry

options for sealing shafts against water entry

(OP)
I am looking at TEFC wound rotor induction motors from 5hp-100hp used in outdoor crane applications.  We have a high incidence of water entering the bearings and causing problems.  

Is there any field-retrofittable method to improve the degree of protection against moisture ingress?  (slinger ring? lip seal? forsheda ring etc).

What about shop-retrofittable options?  

Have you had good experience with simple flexible slinger rings?

RE: options for sealing shafts against water entry

If your getting lots of water in them - I think about a different motor supplier.
Next make sure you have heaters in all of them.  Wire the heaters through a "B" starter contact. If  you have motors positioned where water collect around the shaft turning off a hot motor will suck water right in.
If water is still a problem and you have air available pressurize each motor.  Use a good requlator and put something like a 1/2- 2" " of water pressure on the motor.  To much and you can push the existing seals and greas out.  
I have seen the air thing used in a washdown enviroment and it worked. The motor manufacture didn't want to know anything about it.
Hope that gives you a few ideals

RE: options for sealing shafts against water entry

Greetings electricpete, An Impro Seal is a good option to look at and works very well, The best seal for moisture prevention, (just my opinion) but a little costly. Also you might look at and consider going with sealed (2rs) bearings. I believe you can put rubber shielded bearings up to a 6310-2rs on a two pole motor and as large as they make on a four pole. Your 100hp will probably have 6315-zj bearings, with one steel shield removed.  

When our shop rewinds and rebuilds a wash down immersion duty motor. 1. We rewind with immersion class H winding
materials and a special winding process and use cc1118lv VPI. 2. Use sealed bearings (2rs) 3. Use Impro seals on load end and opp-load end. 4. Silicone all mating surfaces. 5. chico (cement) Junction box lead entrance on stator.

Kind Regards,
motorhead

RE: options for sealing shafts against water entry

Motorhead1 - the company name is Inpro, not Impro.  The type of seal Inpro makes is sometimes called a labyrinth seal.  JM Clipper makes them as well, I think they call theirs the ProTech.  I specify them anytime a motor will be subjected to hosedown and they seem to work pretty well, better than a slinger anyway.

http://www.inpro-seal.com/

RE: options for sealing shafts against water entry

electricpete:- nylos make a very good labyrinth seal and is easy to fit (minimal machining req) we use them along with nsk ddu c3 bearings and water resistant nlgi2 type grease.loctite gasket illiminator is used on all spigots and mateing faces.this type of protection is to ip56.however for a in situ quick fix try a rubber "v" ring but use loctite black max to hold in position and grease the two rubbing contacts. remember that being rubber it will wear and visual inspections will be required.
hope this will help
kind regds.

RE: options for sealing shafts against water entry

(OP)
Thanks everyone, that is some good info.  

I think the Inpro seal will be too expensive to retrofit. We've got several large cranes and I'm thinking around 50 motors involved.  

Some of the other flinger rings I have seen used on transformer fan motors didn't seem to work well although we don't inspect them like TECO recommends.

The two recent failures that I was involved in were bearing failures.  I've been told there were many previous failures but I wasn't involved.  

From all your comments I'm thinking a good approach would be to add a cheap seal and go to sealed bearings. Since this is a very intermittent duty motor it seems like a perfect candidate for sealed bearings (sealed grease should last a long time). I guess I'll have to look closely at the bearing bores and speeds to make sure that won't cause overheating problems.

What do you guys think? Any other comments?

RE: options for sealing shafts against water entry

Suggestion: It appears that the top mechanical bearing expertise may need to participate.

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