Bearing temperature rise due to attrition

[Technopriest]

Hi to you all. I'm new to this forum, so please forgive me if I say nonsenses.
I'm in need of determining the maximum surface temperature of a generic bearing. I'm looking for a formula or something like that that can allow me to have a fair guess of the maximum temperature rise of the bearing.
The bearing may vary in dimension, load and rpm (i need this formula to comply with European ATEX directive). The bearing will however be attached to an agitator (rpm may vary from 20 to 200+ rpm).
I looked for help on SKF site, but the formulas provided there use a 'refrigeration coefficient' that I do not know how to determine.
Any kind of tip or hint will be appreciated.
Thanks in advance.

 

[electricpete]

I don't have much specific, except philosophically there are two types of limits:

#1 - What represents a devition from normal?
#2 - What represents a condition that has the potential for becoming destructive?

For #2 I would say look at your lubrication temperature limit... often in the neighborhood of 220F the aging will greatly accelerate. If you are looking at a rolling element bearing housing external temperature, add approx 15F to estimate the bearing temperature.

For #1 - obviously best accomplished by trending sister units and historical performance. For cooling water pumps and open drip proof motors I often see bearing housings <110F. For totally enclosed fan cooled motors I often see inboard bearing housing in the rang 140F - 180F.

IEEE 841 lists a bearing housing temperature limit for severe duty tefc motors for petrochemical industry - 45C rise above ambient for 4-pole and slower motors, 50C rise above ambient for 2-pole motors.


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[Technopriest]

Thank you Electricpete. But I need a proof that my bearing do not get warmer than the temperature class I choose: for T4 this temperature is 130°C. That's why I'm looking for a formula to calculate surface temperature during normal exercise. It's not a design problem.. it's a problem of European Directives.
The bearing may vary in dimensions, load and rpm, so I would not be happy to TEST every single bearing to demonstrate they do not get too hot..
That's why I can't apply your answer to my problem..


Any other suggestion?


Che Dio ce la mandi buona, o almeno ce la mandi- Massimiliano Eusebi