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<br />molded air inhibited inner corrosion barrier. All resins will be clear to allow detection of <br />subsurface imperfections. Use of pigments, gel coats, inhibitors and additives which <br />may disguise flaws in the laminate is prohibited. <br /> <br />I <br /> <br />1. <br /> <br />1. Housing: Fan housing will be designed so that air leakage <br />through joints and seals is negated. All bolted pieces will be EPDM gasketed <br />for air tightness. Fan housing will be made of FRP construction and electrically <br />grounded. <br />2. Fan Wheel: Type 316 Stainless Steel <br />1) 3. Fan Shaft Shaft will be of Type 316 stainless steel designed <br />to operate below first critical speed. Shaft and impeller will be statically and <br />dynamically balanced at normal operating speed listed in schedule below. <br />Provide teflon or equivalent seal between shaft and housing. Seal will <br />positively prevent liquid and gas leakage. <br />4. Fan Bearing Base: Provide stainless steel fan bearing base. <br />5. Fan Bearings: <br />a. Each fan shaft will be supported by approved, grease lubricated, self- <br />aligning ball or roller bearings made of vacuum degassed 52100 steel. <br />Ball or roller bearings will be made by PROPONENTs who are members <br />of the Anti-Friction Bearing PROPONENTs Association (AFBMA) and will <br />be selected for a minimum rating life (L-10) of 100,000 hours at the fans <br />maximum rated speed and based on Basic Dynamic Load Ratings <br />calculated from AFBMA formulas (AFBMA Standards, Section No.9, and <br />Section No. 11, Latest Revisions). Material factors used in formula <br />calculations will be based on values assuming a conventional good <br />quality, hardened bearing steel without benefit of vacuum degassing. <br />Specifically, for pound and inch units, factor "f' will be as given in the <br />tables of AFBMA Standards cited above. <br />b. The operating internal temperature of ball bearings with ambient <br />temperature of 800F will not exceed 200oF. Temperature measurements <br />will be made with a mercury thermometer. (Thermometers will have an <br />accuracy at 1300F of ::I:20F). Where thermometer wells are not provided <br />or required, the surface temperature of the bearing housing will be <br />measured by a thermometer pressed firmly against the surface and <br />sealed with a suitable plastic putty. Temperature readings during <br />inspection and start-up that exceed 1400F as measured by the <br />thermometer-surface method, will be deemed presumptive evidence that <br />the operating internal temperature of the bearings exceed 200oF, unless <br />PROPONENT can conclusively prove otherwise to the satisfaction ofthe <br />CITY or CITY'S representative. In the absence of such proof, it will be <br />incumbent to reduce the temperature at or below 1400F with no additional <br />cost to the CITY. <br />c. Bearing temperature will not exceed 22soF at the fan's maximum rated <br />speed. <br />d. Computations on bearing selection will be submitted for approval and will <br />show complete details of loading. A dynamic factor of 2.0 will be applied <br />to loading. Ball and roller bearings will be enclosed in oil-tight housings <br />equipped with approved shaft seal rings and will be suitably arranged for <br />high pressure grease lubrication. <br />e. The bearing supports for the shaft will be of rigid design and will be <br />securely fastened to the base to ensure the proper alignment of the main <br />shaft bearings. <br /> <br />I <br /> <br />I <br />