Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/490438
16 March - April 2015 | www.machinerylubrication.com The "Lube-Tips" secTion of Machinery Lubrication magazine feaTures innovaTive ideas submitted by our readers. additional tips can be found in our Lube-Tips email newsletter. if you have a tip to share, email it to us at editor@noria.com. To receive the Lube-Tips newsletter, subscribe now at www.machineryLubrication.com/page/subscriptions. Precautions for When Compressors Run Hot Most coolers today operate close to maximum capacity if the compressor is operating at full load. If the ambient temperature around the compressor increases and does not provide additional air flow to remove the excess heat, you will run into a situation where the compressor runs hotter. Most manufacturers design their coolers for 100-percent capacity at an ambient temperature of 100 degrees F (38 degrees C) and 70-percent relative humidity. If conditions around your compressor are more severe than this, special precautions may be necessary. For a rotary compressor, a temperature of 212 degrees F (100 degrees C) is not excessively high. Most compressors have a cutoff at 225 to 235 degrees F (107 to 113 degrees C). Keep in mind that at temperatures above 190 degrees F (88 degrees C), fully synthetic oil is necessary. Have a sample of the oil analyzed every 500 hours to verif y the oil condition. Also, inspect and clean the coolers regularly. Benefits of a Simple Tank Modification A diffuser fitted to the return line of a tank can reduce foaming and thus decrease oxidation and aeration as well as the risk of cavi- tation. It can also lessen the potential for varnishing, erratic fluid flow, spongy hydraulics and overheating. Advice for Checking Oil Levels When checking the oil level in a centrifugal pump, it is a good practice to have a sight glass on both sides of the pump. If the pump is not centered in the casing, the oil level will not read correctly in the sight glass. It may read low on one side and high on the other. An average of the two readings will give an esti- mated oil level. Procedures Can Improve Oil Analysis Data Consider creating specific written procedures for oil sampling. This helps standardize the sampling so that each oil sample is taken in a consistent manner. It will also help minimize the variability of your oil analysis data. In addition, procedures can be useful for training new team members. What to Check Before Switching greases When converting from one grease to another, double-check to make sure that your soap bases and oils are compatible. The simple way to do this is to have your supplier or an independent lab perform a worked penetration test on a mixture of the greases. Alternatives to Synthetics Severely hydroprocessed and hydrocracked base stocks may be a suitable alternative to polyalphaolefin (PAO) synthetic lubricants for many applications at a much lower cost. Some of these lubri- cants have very high viscosity indices and excellent resistance to oxidation and thermal failure. greases That Resist Oxidation Polyurea greases have very good oxidation resistance because they don't contain metal soaps such as calcium, lithium, etc., which are pro-oxidants to varying degrees. Therefore, they can be used in lubed-for-life bearings. Tip for Installing Breathers When installing fine-filtration (3- to 10-micron) reservoir breathers, make sure the breather has an internal differential pres- sure gauge to alert you when the filter is dirty. If your breathers do not have this built in, add pressure and vacuum gauges to the reser- voir headspace. Then add inspection of these gauges, while the machine is in normal operation, to your pre-PM checks.