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whether you may see a significant reduction in motor power needed depends on the quality of the present lubrication. if the oil used now is able to sustain a suitable film thickness under all operating conditions, you may not see any difference. if however the load on the gears is such that there is partly mixed lubrication a synthetic oil of the poly alkelene glycol variety may make some difference, because it's adherence to steel surfaces is better then with mineral oils. usually the effect seen in actual practice is a quite measurable lower operating temperature, and that may be also measured in terms of power consumption.

in this particular case were a ISO VG 100 oil is used it may perhaps not be worth the extra cost, because the low viscosity indicates that gear loading is rather low and/or gear speed high. the effect will be more visible with higher loaded slow running gears requiring oils within the ISO VG 220 - 460 region.

apart from possible better lubrication a synthetic gear oil may make it possible to extend drain intervals that can lead to lower oil costs, lower maintenance costs and lower disposal costs of used oil.
RM
sathappan, I suggest you go back and read the thread at http://maintenanceforums.com/e...451/m/6711069492/p/2. My comments there I think address the use of synthetic oil in the presence of moisture in a cooling tower, something I highly recommend. I note that at the end of that thread, which was started on 29 January 2007 and you added to it this past May, you posed the exact same question and there were no responses to your inquiry about power conservation using a synthetic, which I will attempt to address now.

In theory a synthetic lubricant can reduce the energy demand on the prime mover. However, in the typical cooling tower gear drive the reduction of losses is very small, and the payback period with the higher costs of a synthetic may be quite long. In my experience the typical cooling tower gear drive, a double reduction, will have an overall drive efficiency around 90% to 92%. I'll make some educated and experience based guesses and explain that number. The 1st reduction is likely a bevel gearset with a typical efficiency of about 95% to 97% and presents the area, at least considering the gearing, with the greatest amount of sliding and hence losses, and even that is minimal. The 2nd reduction, being a helical gearset, and operating at lower speeds, will have an efficiency of about 98%. There are rolling element bearing losses and with six bearings in total I would estimate something around 3% to 4% loss total. Looking at the individual areas the most potential gain for efficiency is in the bevel reduction and in the bearings, but I would estimate you could only gain 1% in the bevel gearset and perhaps 1% in total in the bearings. So in total you might bring the overall efficiency of the drive up from about 90% to about 92%. You don't state your motor size, but you could go in and look at that energy consumption savings and weigh that against the increased cost of the synthetic lubricant.

I must emphasize that the primary consideration that should drive one to selecting a synthetic lubricatant is moisture ingression into the lubricant. If this is occuring, and verified through regular oil analysis, then "yes" consider a move to a synthetic. It has been well documentated that moisture in lubricants can significantly reduce the life of rolling element bearings. Sythetics lubricants, through their chemical makeup, make this less of an issue. But to expect significant energy gains through the use of synthetics in a cooling tower is just not likely to happen.

Some other worthwhile comments relative to cooling tower operation can be found at the two threads below.

http://maintenanceforums.com/e...20526173#67720526173

http://maintenanceforums.com/e...20438963#88220438963
RM
Last edited by Registered Member

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