My company has just been asked to supply our mixer for agitating sludge in a waste fuel rail car for offloading.  The tank may contain any combination of very volatile fuels including Benzene, Acetone, Toluene, diesel, and more generic fuels as well as waste from paint shops which could include Turpentine, Alcohol, Mineral Spirits, etc. The customer confirmed that the volatile fuels can go right to vapor and fill the air void in the top of the tank above the liquid.  There is no way to keep the more combustible fuels suspended or dissolved in the rest of the liquid in the tank.  They have grit, sand, pebbles, broom handles, rags, etc. in the mix and our mixer will help them pump out any and all solids.  

Our mixer consists of a 10hp motor driving a shaft and metal square pitched prop spinning at 1750rpm in a metal draft tube.  The shaft is supported top and bottom by bearings so there is potential for metal to metal contact and heat buildup.

The mixer is to be Class I Div 1 but this NEC code only applies to electical components.  Is there is code that would apply to mechanical equipment in an explosive environment?  Bill