Duty & Insulation: Insulation class F with constant duty (s1) Cooling tower motor design for Working S1Duty. For continues working. Motor relative humidity up to 90% Shaft and Bearing: Our cooling tower Motor relative humidity up to 90%. Cooling tower Motor Shaft is Mead by stainless steel material AISI-410. Nut and washer are made for stainless steel AISI-202. It can make protection against corrosion. Motor shaft extended so cooling fan fitted properly.