Daikin RDT-135c Installation And Maintenance Manual

Contents

Daikin RDT-135c Installation And Maintenance Manual Manual pdf 117 page image

IM 738-2 115Maintenance: SetscrewsFan Shaft BearingsRelubricate fan shaft bearings periodically. Relubricateaccording to the schedule shown in Table 26. If the bearingsare exposed to wet conditions, wide temperature variations, orother severe atmospheric conditions, relubricate morefrequently. Use one of the greases shown in Table 25.While the bearing is at normal operating temperatures, rotatethe fan by hand and add only enough grease to purge the seals.The seals bleed slightly when this occurs. Do not overlubricate.Propeller ExhaustFor more information, see page 96.Vibration LevelsEach unit as shipped is trim balanced to operate smoothly. Toprovide satisfactory operation after shipping and installation,use accepted industry guidelines for field balancing fans. SeeTable 27.Note: Excessive vibration from any cause contributes topremature fan and motor bearing failure. Monitoroverall vibration levels every six months of operation.An increase in levels is an indication of potentialtrouble.Vibration Causes1 Wheel imbalance.a Dirt or debris on wheel blades.b Loose setscrews in wheel hub or bearing-to-shaft.c Wheel distorted from overspeed.2 Bent shaft.3 Faulty drive.a Variable pitch sheaves—Axial and radial runout offlanges; uneven groove spacing; out of balance. Alsosimilar faults in driven sheave.b Bad V-belts; lumpy, or mismatched; belt tension tootight or too loose.4 Bad bearings, loose bearing hold-down bolts.5 Motor imbalance.6 Fan section not supported evenly on foundation.Periodic Service and Maintenance1 Check all moving parts for wear every six months.2 Check bearing collar, sheave, and wheel hub setscrews,sheave capscrews, and bearing hold-down bolts fortightness every six months.SetscrewsSetscrews are used to lock bearings, sheaves, locking collars,and fan wheels to their shafts. They must be checkedperiodically to see that they have not loosened. If this is notdone, severe equipment damage could occur.Using Table 28, check the tightness of all setscrews with atorque wrench. Note that if the return fan bearings setscrewsmust be retightened, a special procedure is required to equallyload both bearings (see “Return Fan Bearing Setscrews”below).Return Fan Bearing SetscrewsBecause the return fan is mounted on a vertical shaft, thefollowing procedure must be used to retighten any return fanbearing setscrews that have loosened. This procedure willprovide that both bearings are equally loaded. If one bearing iscarrying the entire weight of the fan, it could fail prematurely.1 Loosen the fan belts.2 Support the weight of the fan and the fan shaft with timbersor some other suitable means (see the fan shaft support inFigure 114). Important: To maintain proper drivealignment and fan-to-tunnel clearance, the fan and shaftmust not drop at all when the setscrews are loosened inStep 4.3 Verify that the upper shaft collar is securely fastened to theshaft. Check the setscrew torque.4 Loosen the upper and lower bearing setscrews. The entireweight of the fan and shaft is now supported by the fanshaft support.5 Retighten all bearings to the torque specification given inTable 28. Remove the fan shaft support and retension thebelts.Table 25: Recommended greasesManufacturer Product name Temp. range (°F)Texaco Lubricants Co. Premium RB -30 to 300Keystone Ind. Lubricants 84EP-2 -40 to 200Mobil Oil Corporation Mobilith AW2 -40 to 325Chevron U.S.A. Inc. SRI-2 -20 to 325Exxon Company. U.S.A. Ronex MP -40 to 300Shell Oil Company Alvania No. 2 -20 to 240Table 26: Recommended fan shaft bearing lubricationintervalsOperatingdutyBearing ambient temperatureTo 130°F To 150°F Over 150°FContinuous 6 months 4 months 2 months12 Hrs./Day 12 months 12 months 6 monthsTable 27: Vibration levelsFan speed (RPM) Vibration800 or less 5 mils maximum displacement801 or greater 0.20 in/sec maximum velocityTable 28: Setscrew minimum torque specificationsSetscrew diameter (in.) Minimum torque (ft.lb)1/4 5.55/16 10.53/8 19.07/16 29.01/2 42.05/8 92.0