I have a large, 1200 Ton chiller that was filled with water. We have partially dissasembled it, and we are now considering the best way to clean the rust, etc. from the interior. Has anyone tried dry ice blasting for this kind of thing? I am particularly interested in trying it on the motor, which I have removed the end bell from. If I could clean the thing in place, witout having to dismount it, I would be miles ahead. Has anyone ever dry ice blasted motor windings on a 4160 V motor?

Thanks in advance for any thoughts.

I guess you should post this equstion on the Motor Testing section to get the right crowd.

Some years ago a ship's propulsion motor got "gunged" up. I used dry-ice blasting to clean the windings. The motor was 6,600V. The size as I recall was around 6MW. The blasting worked a treat, dislodging the gunge without damaging the insulation itself. The windings involved were large formed coils.

If I only wanted to clean the parts of the windings that I can see and the cleaning needed to be done in-situ, then I would definitely consider using dry-ice blasting again.

One factor to remember if you do try this is to ensure good ventilation.

Dry ice blasting is fairly commonly used for motors. EPRI has studied it and found it to be effective for general cleaning, except that it does not remove oil particularly well. The big benefit of course is there is nothing to clean up (as opposed to walnut shells, corn-cob etc), and generally no drying required (as opposed to steam cleaning). The pellets simply evaporate.

We had one of our 13.2kv motors cleaned by dry ice and I was pretty impressed that it was quick and effective.

I suspect as in all things that the skill of the person doing the job matters. He needs the right size pellets and the right velocity and right distance of nozzle from cleaned surface. Personally, I would prefer to coordinate this through a motor repair shop (some offer this as a service) rather than going to a general cleaning company that doesn't specialize in motors. An example of an area that would be particularly vulnerable to damage from reckless/sloppy work is the stress control coatings on medium voltage motors.

Can you take before and after pictures? Which ever way you clean would be of interest.