Washdown and Sterilization 1

[Clyde38]

I’m looking for feedback on the following questions with regard to washdown (TENV, TEFC, etc.) and sterilization (autoclave, etc.) of motors (DC, AC, Step motor, etc.):
1. What kind of problems do washdown and sterilization cause to electrical or mechanical components or functions?
2. How do these anomalies form? (i.e. corroding material, lack of attraction in magnetic field, low power transferring thru motor, skipped steps...)
3. When do these problems form? (ie during cleaning, next day / after hours of continuous operation)
4. How are they addressed?
5. Are there regulations that apply when designing motion components that will be exposed to washdown/sterilization.
If there are washdown/sterilization points you wish to cover that aren't addressed by these questions, please include that info. The topic is open and these questions are meant to broaden my knowledge with your experience.

 

[ejc]

I can’t answer a lot of your questions, as I mostly deal with bearing protection, but I’ll let you know what I can.
Washdown of motors, or any bearings, can lead to premature failure of the components. The water (or solution) gets into the bearing and attacks the lubrication very quickly. Once the lubrication is compromised, the bearing fails rapidly.
For information on design of washdown, etc, I suggest the IEEE standard 841. This in turn will lead you to the NEMA specification MG1, which describes the tests that components have to pass with regards to water exclusion.
I’m sure others on the forum can help with other components and the sterilization areas of your question.

 

[itsmoked]

Part of the wash-down problem is that often you use "dairy" hose (white) with which to blast everything in site with 180F water which provides sterilization. Well once this heated water hits say a cold motor it quickly heats the motor up. Now you have a hot motor covered with water cooling. The cooling creates a vacuum in the motor housing that sucks in the external standing/dripping water... Water + motor windings = unhappiness.

 

[Barry1961]

The best washdown motor I have run into is Franklin Hydro Duty. Their main business is making submersible pumps. The submersible motors can be smaller in most cases due the water being a good coolant. The washdown motor they make is larger with no fins to catch trash but it runs hotter than a standard TEFC when dry. These have just been out 3 or so years and have had great success in very harsh and wet conditions. They have replaced motors that were lasting less than 60 days and have not failed in a couple of years. I have not heard of the higher operating temperature causing problems yet but jury is still out. If you have an application that is wet most of the time they are the best I have ever run into.

The best washdown gearbox I have run into is Stober. They are very popular in food and poultry. Some of the things to look for in a washdown box:

Output seal guarded from direct high pressure spray.
No breather vent.
No pockets to trap water or trash.
Tough paint/coating.

Stober is coming out with a new box just for food/poultry washdown that has a very smooth and rounded casting, totally sealed and shielded wobble free hollow quill, new tougher stainless paint and extra input seal. I have not seen these on equipment so they must still be in testing. From the pictures I have seen they will be very popular due to the casting shape being very easy to clean. It looks like you could pour a bucket of dry rice on it and it would shed every grain.

You should be able to go on their websites and see what they are bragging about. I think the new Stober is still a secret so don’t tell anyone.

http://www.stober.com/

http://www.franklin-electric.com/

Barry1961