Perchloric Acid in fume form is Explosive and all possible precaution should be taken to eliminate areas that could collect fumes and dry out to form some type of compound that could be explosive.
Construction Highlights:
Fans are constructed with machined Metal-to-Metal fits at the inlet and drive side plate to housing junctions. No paint or coating on the Air-Stream Wheel and shaft constructed out of Monel (Nickel-400) Air-Stream exterior painted RED
Housing Drain Plastic laminate tag affixed to fan stating "Because of the hazardous quality of gases through this fan, NO gaskets or gasket materials are to be used" All burrs and rough edges are ground off the housing interior and air-stream