I just bought the 8" version and it's pretty awesome, nicely built, very quiet, and two year replacement warranty.

However, it says right on the front of the instructions not to use in hazardous atmosphere, explosive gasses, significant dust, or near open flame. :eek:

Personally I'm not too worried for two reasons:
1) I don't think any brushless motor (EC, sealed, or otherwise) is capable of producing a spark, other than by static electricity on the housing or ducting, and
2) I don't think the concentrations will get anywhere near the explosive limit as stated by Jason

Watch for my obituary... :p

Ok, still not too worried, but after some asking and googling I do have more info on the matter.

Someone who works a lot with motors had the following to say:

"My thoughts on this: in terms of the electronic components, none of them should create sparks during their operation, but they still could, if they get damaged in some way. A brushless DC motor could still create a spark, when an electronic component has a fault. MOSFETs can literally explode. The windings could also create a spark, when the protection diodes were damaged. Other than electronic faults, a mechanical fault could have similar effects: Say the bearing wears out and steel rubs against steel! These are just ideas off the top of my head. I have not had to deal with ex-proof fans and I don't know how the difer in terms of their design."

Then after a quick search I found https://www.airsolutions.us/news/new...on-proof-fans/, which had this to say:

"Did you know that technically there is no such thing as an explosion proof fan? While there are enclosures and motors that are rated explosion proof, it is not possible to rate a fan as explosion proof. The reason: explosion proof design requires isolation from the potentially explosive air. By nature of the way a fan operates, a potentially explosive air stream will always be in contact with the interior of the fan housing and the fan impeller."

Apparently the appropriate fan standard is called spark-resistant, and makes no mention of brushed/brushless motor design. The standard, linked below, basically boils down to it's first footnote: "No bearings, drive components or electrical devices shall be placed in the air or gas stream unless they are constructed or enclosed in such a manner that failure of that component cannot ignite the surrounding gas stream."

So I guess people marketing explosion-proof/resistant fans are really selling spark-resistant fans with explosion-rated motors. A technicality perhaps, but interesting, at least to me. :)

http://www.reahvac.com/tools/amca-standard-99040186/