[QUOTE=Loves to ride;8243144]
Sigh. As DHCarrotFeeder (David) points out, these fans are not sealed motor, even though the description and the customer service person whom I talked to both said they are usable in barns.
I ordered 4 and they just arrived. I was so excited to see them! Opened a box and saw the copper wires of the motor. 
So is this fan safe for barn use? Or do I need to swear a lot and send them back. (Just kidding on the swearing!)
The description from FarmTek:
Powerful hanging fans keep you and the workplace cool and comfortable• Kits include ValuTek 3-speed fan with 6’ plu-in cord, 5’ chain and S-hooks.
• Perfect for greenhouses, shops, garages and barns. (bold is mine)
• Hang over the purlins in your greenhouse to circulate the air and protect your plants and flowers.
• 3-speed fan allows you to customize your ventilation needs.
• Commercial-grade motor is engineered to use less current.
• Can also be used as a floor fan (feet included).
• Completely sealed and permanently lubricated ball bearings with thermal overload protection and rotary switch.[/QUOTE]
I think as long as you inspect them periodically and keep the insides cleaned of dust. Dust that collects in there will cause them to overheat and become a primary ignition source.
David