We decided to powdercoat the housing itself in a high gloss powder and coat the fan blades in anti-graffiti coating. We worked with the customer to implement a P.M. program where they power wash it monthly. The anti-graffiti paint allows the build up to easily come off when washed.
We added stiffener rings to the outside housing to keep it from deforming when/ if the motor failed.
To eliminate the fins from cracking, we added a band to the outside of the housing and connected the tie bars on the back of the motor in a 45 degree direction to absorb radial torque from the motor.