Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1275515
38 | July - August 2020 | www . machinerylubrication.com heat. Using the back of your hand, you can lightly touch a surface to gauge how hot or cold it is. Remember, some machines may be incredibly hot so it is best to quickly touch something and if you are uncertain how hot something may be, use a non-con- tact thermometer to collect your temperature information instead. • Contaminants – if done correctly you can capture purged grease or sludge from a system in a plastic bag. You would then roll the bag between your fingers trying to determine if you feel any solid contami- nants and try to isolate them. To increase the power of this simple experiment you can use latex gloves and swirl the lubricant between your fingers. Your fingertips are incredibly sensitive to any grit or debris that may exist in the lubricant. Using a magnet in concert with this inspection can help determine is the solid is ferrous debris or not. • Lubricant – while wearing gloves, you can inspect both greases and oils to crudely determine if they are still fit for service or not. When feeling greases, you would want to ensure that the mixture is smooth and doesn't crack or bleed exces- sively when moving it through your fingers. Oils should be slick and not overly tacky. Comparing in service lubricants to new lubricants will provide useful insights to how the lubricant may have changed during service. • Vibration – most people equate vibration analysis with collecting data and then analyzing the waveform back in the office. You can also inspect for abnormal vibra- tion in the field using your hand or screwdriver. By placing your hand on the house of a machine you will feel the oper- ational vibration of the equipment, as you move your hand from the inboard side of the machine to the outboard side, try to feel for any change in this vibration. By using something like a screwdriver and placing the tip on the machine, this vibra- tion is transmitted to the handle which may make it more sensitive to determining if there is an issue. Olfactory Inspections Don't overlook your sense of smell during your inspection rounds. is is a powerful tool, especially when it comes to diagnosing issues with lubricants. Many different compounds can be generated and exist within lubricants, all with their unique odor that, with time, can be identified. Perhaps one of the most common expressions heard when dealing with failed equipment is, "something smells burned." is is an inspection type that does require some caution and it is always best to gently waft the smell towards your nose as opposed to bringing in a big breath. is is also an inspection that is best done from oil in a sample bottle as opposed to being in the field because of added vapors or fumes that may be present that could impact the sensitivity of your nose. • Contaminants – some volatile contami- nants are very easily detected by sniffing the oil sample. ings like fuels (diesel and gasoline), solvents and light hydrocar- bons are easily found during this type of inspection. e smell test can be further confirmed by looking at viscosity or flash- point which would both indicate the contamination by a drop in their values. • Microbials – in equipment that is commonly contaminated with water and/ or food materials, it is possible for the lubricant to promote the growth of bacteria or microbes. Left unchecked these contaminants can turn the lubricant incredibly acidic and begin to clog passageways restricting oil flow. During a smell test, you can identify these contam- inants by a very noticeable rotting smell or road-kill smell. • Oxidation – this is the primary failure mechanism for base oils and as such, there are many ways to inspect for it. Using your sense of smell you will be able to identify a distinct burned smell that is somewhat pungent. To confirm that oxidation is the issue, perform a quick visual inspection. If the oil sample is dark and has a pungent odor, oxidation is the most likely issue. • Thermal – similar to oxidation this process will involve a darkening of the oil. However, during a thermal failure there will be no distinguishable smell. In some thermal failures, the volatile components of the lubricant have all be evaporated so what is left will be devoid of an odor. If you have a dark oil sample and no odor, check for contaminants or a thermal failure as the cause. Modifications As discussed, many pieces of equipment come with the proper accessories to be prop- erly or even easily inspected while they are in services. ankfully there are many devices that can be retrofitted to most equipment to make these inspections a reality. While some may require more modification than others, there are many relatively simple modifications that can greatly enhance your inspection program. • Sightglasses with marks – anything used to determine the proper oil level should be marked with the normal running ("hot") oil level as well as the off ("cold") oil level. Simply putting a pencil or ink mark on the glass is not good enough and may cause confusion. • Breathers with vacuum/pressure gauges – breathers that don't have a change indi- cator built in should be equipped with an external vacuum or pressure gauge. is will indicate if the breather is plugged and not breathing correctly. Even desiccant breathers should be outfitted with one as they can become clogged before the desic- cant is saturated and a color change occurs. • Expanded metal – replacing sheet metal guards with expanded metal will allow for the visual inspections to occur without introducing a safety issue. For added ease, paint the expanded metal black to allow your eyes and camera lenses to see past the guards to the equipment more easily. • Leak absorbent materials – by placing oil absorbent matts or pads under oil-filled equipment, it will provide for a quick visual reference point if there are any leaks coming from the housing. Sometimes small leaks can blend in with the adjacent concrete. e absorbent material often IN THE TRENCHES