Expert Forum: Extend the life of equipment by 5 to 10 times
author: Leila
2024-10-16
"Wash your hands before and after meals" - this is a basic requirement for personal hygiene. For equipment lubrication management, "keeping the oil clean" is a basic requirement for maintaining the equipment well. Keeping lubricants and greases clean and avoiding contamination not only helps to extend the service life of oils, but also helps to extend the service life of equipment, reduce equipment failure rate, and reduce maintenance costs.
At the annual meeting of the American Society of Tribologists and Lubrication Engineers (STLE), Dan Holdmeyer gave a report on the theme of "Keeping Oil Clean". Dan Holdmeyer comes from Chevron, a world-renowned lubricant company. As a field technical specialist and lubrication engineer for Chevron, he has more than 30 years of experience. In his report, Dan Holdmeyer shared his experience, pointed out the various links of lubricant contamination, and the hazards of lubricant contamination, which can be called a master-level lecture. This article excerpts the key points of Dan Holdmeyer's report, advocating keeping oil clean, extending the service life of equipment, and maintaining healthy operation of equipment.
Two major hazards: impurities and water
Many equipment failures are caused by lubrication problems. Among them, impurities entering the oil is the number one cause of lubrication failure, followed by water. These two contaminants are problems that may be encountered in any application occasion. Therefore, impurities and water must be strictly prevented from entering the oil.
Holdmeyer emphasized: "The wisest way is to prevent water and impurities from entering the lubricating oil from the source, with prevention as the main focus. Preventing impurities from entering the oil certainly requires some investment, such as purchasing breathing caps and using high-efficiency seals, but once impurities enter the oil, it takes about 10 times the money to get them out. In other words, if "pollution prevention" costs 1 yuan, "pollution treatment" costs about 10 yuan."
Three major ways for lubricants to be contaminated:
To ensure the cleanliness of lubricants, which links should be started? Holdmeyer said that the storage, packaging and use of lubricants are the three basic links of pollution control.
l Lubricant storage: In actual operation, lubricant contamination is usually such a situation: the equipment manufacturer specifies the ISO cleanliness level that the lubricant needs to reach for the user, and the user purchases lubricants that meet the corresponding standards according to the specified level. After the oil products are transported, they are stored in the warehouse, but some users store them outdoors. Because the users do not pay attention to sealing the oil products, or water accumulates on the top of the oil barrel, the lubricating oil absorbs moisture or impurities during the storage process.
l Repackaging: The lubricating oil may also be contaminated during the repackaging process. The tools such as oil barrels, oil pots or funnels used by users are not clean, and there may even be old oil left inside the container, or different oil products share a container or tool, causing the new oil to be contaminated.
l Oil use: Lubricating oil may also be contaminated during the oil use process. For example, if the equipment vent is not equipped with a breathing cap (also known as a breathing cap or respirator), impurities, dust, and moisture in the atmosphere enter the lubrication system from the vent; if the oil tank is not covered well, impurities enter the oil tank; if the oil tank is rusty, rust residue falls off and enters the lubrication system; if the seal is not tight, moisture and impurities enter the oil, etc. Because lubricating oil is hygroscopic and absorbs moisture in the atmosphere, the equipment vent should be equipped with a breathing cap with a drying and dehydrating function.
To extend the service life of lubricants and equipment and reduce lubrication failures, it is necessary to prevent the lubricants from being contaminated during use. First of all, written operating specifications should be formulated for the storage, subpackaging and use of lubricants.
Holdmeyer gave several suggestions for the storage of lubricants. First of all, the lubricating tools used should be properly stored and used for specific purposes. Store various lubricating tools indoors and keep the room clean and tidy. If conditions permit, try to choose to store oil products indoors. Because the temperature difference outdoors is greater than that indoors, the sun is exposed during the day and the temperature drops at night. The repeated large temperature difference changes are not conducive to the stability of lubricant additives. Large temperature differences also make it easy for lubricants to absorb moisture in the air. Outdoors are also prone to sun and rain. If the oil barrel is placed vertically, water is easy to accumulate on the top, causing the lubricant to be contaminated by water. Therefore, when storing lubricants outdoors, they should be covered with waterproof cloth to prevent sun and rain. It is best to place the oil barrel horizontally or tilt it sideways to prevent water from accumulating on the top of the barrel.
During the subpackaging and filling of lubricants, it is necessary to use specific instruments for specific purposes, and the tools that are reused should be cleaned in time to ensure that they are clean and dry for the next use. It is best to arrange a room to store the large iron barrels, plastic barrels, oil dispensers, and related tools used for oil transportation. Holdmeyer also recommends that the refueling and dispensing tools used be distinguished by plastic labels of different colors. The rags used should be clean and not easy to shed, and the trash cans should be covered.
During the refueling process, it is recommended to use a small mobile filter refueling truck. This refueling truck has a fuel tank, a built-in filtration system and a refueling pipe, which can filter the oil before adding it to the equipment. The filtration accuracy of the refueling truck can be selected according to the required ISO cleanliness level. In order to avoid adding the wrong oil, in addition to labeling the equipment, oil barrels, and various refueling tools, different refueling port connectors can be used. Specific lubricants are installed with specific refueling port connectors to avoid misuse of oil.
The choice of oil packaging is particular:
Oil will slowly oxidize after contact with air, so the oil will oxidize and deteriorate after long-term use after opening. Oversized oil storage tanks may not be suitable. If the amount of oil used is small or the number of times it is used is small, there is no need to use large barrels of oil, because the remaining oil will be retained in large quantities. If stored for a long time, the lubricant will not be fresh enough when it is used. "If the amount of lubricant used and the use of the lubricant are more suitable for lubricants packaged in small barrels, then the ISO cleanliness of the lubricant shipped from the large barrel or oil tank must be ensured to meet the standard, and it must also be filtered when it is divided into small barrels. Large oil tanks should be equipped with dry breathing caps (vent caps) to prevent dust, impurities, water and moisture from invading. Holdmeyer said: "The oil tanks used to store lubricants should be sampled and tested at least once a year, and cleaned at least once a year to prevent moisture or impurities from contaminating the oil tanks. If there are no conditions to do these things, at least flush the oil drain port and visually inspect it. ”
We have emphasized before that it is important to take measures to prevent impurities in lubricating oil from entering the oil. To do this, we must first know where the contaminants in the oil come from. Are these impurities generated by the equipment, or are they brought in during storage? Or are they brought in when collecting oil samples? Are the oil products not sealed properly? We must fully consider various possible reasons to effectively cut off the source of pollution from the source.
"Although these are small details and not high-tech, there are many cases where these details are not done well, such as a simple oil tank not covered properly." Holdmeyer said, "Whether it is during daily maintenance of equipment operation or during the process of adding lubricating oil, contaminants may be introduced into the lubricating oil. At any time, the lubricating oil in the oil barrel should be filtered before adding it to the equipment. "
Hydraulic equipment is very sensitive:
"Although all equipment is very taboo about water or other impurities in the oil, hydraulic equipment is particularly sensitive to impurities, and the adverse consequences of impurities will occur quickly. "Holdmeyer said, "Because the gaps between hydraulic equipment parts are generally very small, for example, the gaps between servo valves are only 1 to 4 microns. What does such a small size mean? The particles of talcum powder are about 10 microns, and the size of bacteria is 2 to 3 microns." In order to prevent tiny impurities from getting stuck between parts, we must allow the impurities to pass through the gaps between parts smoothly. To do this, hydraulic equipment manufacturers specify the ISO cleanliness level of lubricating oil for users. The ISO cleanliness level specifies the size of impurity particles allowed by the equipment (4 microns, 6 microns, 14 microns) and the number of particles. If the particle count exceeds the specified ISO cleanliness level, the user must immediately take oil cleaning measures or replace the oil. The ISO cleanliness level requires the detection of the number of particles of three sizes: 4 microns, 6 microns, and 14 microns, but some hydraulic equipment manufacturers specify the detection of two of the particles, such as Caterpillar .
Holdmeyer reminds users that if impurities in the hydraulic oil are not removed in time, it will cause wear of the hydraulic valve, leading to a series of faults such as slow response, blockage and jamming of the hydraulic valve, metal corrosion on the valve core surface, burning of the solenoid valve, and failure of the safety system. Impurities can also cause wear of the hydraulic cylinder, especially for construction machinery. Because construction machinery is easily contaminated with dust and impurities, damage to the piston rod and seal is the main reason for the entry of impurities. Observe the piston rod when it comes out of the cylinder. If you find oil on it, then check it.
The first line of defense - filtration:
For most equipment, the lubricating oil filter is the first line of defense for oil. According to Pall Corp., Holdmeyer said that good filtration combined with proper oil maintenance can extend the service life of oil pumps and equipment by 4 to 10 times! Rolling bearings can even extend their service life by 50 times. Other benefits include extending the service life of oil products, and reducing the cost of purchasing new oil, changing oil, and disposing of waste oil.
Users will find that all filters or filtering equipment have filtration accuracy, but I would like to say that filtration accuracy can sometimes be misleading. "If the filter is marked with a nominal rating, then this accuracy does not mean anything, because the nominal rating is just a one-time arbitrary value given by the manufacturer and may not be reliable in use. If you see the nominal rating given by the filtering equipment, then the user should question its filtering effect." Holdmeyer affirmed, "Users should pay attention to the absolute rating of the filter. The absolute rating shows the maximum size of the filter hole and how large the particles can pass through the filter element."
Holdmeyer continued: "In addition to absolute accuracy, there is another important indicator of the filter, which is the filtration ratio, that is, the Beta Ratio (β value). The filtration ratio = the number of particles of a certain size before filtration / the number of particles of the same size after filtration. Let's give an example to illustrate. If the number of 6-micron particles in the oil upstream of the filter is 1 million, and after filtration, the number of 6-micron particles in the oil downstream of the filter is reduced to 500,000, then the β value is 2 and the filtration efficiency is 50%. If the 1 million particles are reduced to 1,000, then the β value is 1,000 and the filtration efficiency is 99.9%. [Note: The conversion formula between the filtration efficiency (%) of the filter element and the β value is: ((β value-1)/β value) x 100. ]
According to our experience, high-pressure equipment has higher requirements for oil cleanliness. High-pressure equipment has stricter control requirements for oil flow, and higher requirements for the speed and accuracy of the control valve, so the requirements for oil cleanliness are also stricter, because the equipment clearance is more precise, and impurities in the oil are more likely to cause equipment failure. Compared with low-speed sliding bearings, high-precision rolling bearings have more stringent requirements for the cleanliness level of lubricating oil.
Hazards of water:
Next, Holdmeyer talked about the hazards of water to lubricating oil. Water is the second culprit of lubrication failure. Only 400ppm of water in the oil can reduce the life of rolling bearings by up to 85%. Common sources of water are moisture in humid atmosphere, condensation caused by temperature drop, storage of lubricating oil in oil tanks, and some water dissolved in the oil in the oil tank. Water gun flushing and flushing are also common causes of water ingress, as well as cooling water leakage, oil seal damage or improper installation.
Visual inspection and laboratory instrument testing are both It can be found that water has entered the oil. The latter is more accurate and can also find less dissolved water. Another method is the heating method. The general practice is to heat the lubricating oil on an iron sheet. If a crackling or popping sound is heard, it means that there is water in the oil.
Holdmeyer said that during the on-site inspection, he found that in many cases, everyone thought it was a closed circulation lubrication system, but water actually entered. The reason lies in some very small details, such as cracked oil mirrors, leaking seals, etc. Sometimes it is not done correctly when adding or draining oil. New oil is added without filtering, and water or impurities in the oil are added. In some cases, the vents of the equipment are not equipped with effective air filters, or the old-fashioned covers are not sealed, resulting in impurities in the atmosphere and moisture in the air entering the equipment. It is recommended to use a breathing cap with a desiccant to effectively isolate impurities and moisture in the air.
Holdmeyer finally concluded: "To lubricate the equipment well, the lubricating oil must be kept clean and free of water. Users must ensure that the oil is clean before adding it to the equipment. Store lubricating oil and grease properly, keep the oil clean during use, and do not use dirty, linting rags to wipe grease fittings or oil filler ports.
At the annual meeting of the American Society of Tribologists and Lubrication Engineers (STLE), Dan Holdmeyer gave a report on the theme of "Keeping Oil Clean". Dan Holdmeyer comes from Chevron, a world-renowned lubricant company. As a field technical specialist and lubrication engineer for Chevron, he has more than 30 years of experience. In his report, Dan Holdmeyer shared his experience, pointed out the various links of lubricant contamination, and the hazards of lubricant contamination, which can be called a master-level lecture. This article excerpts the key points of Dan Holdmeyer's report, advocating keeping oil clean, extending the service life of equipment, and maintaining healthy operation of equipment.
Two major hazards: impurities and water
Many equipment failures are caused by lubrication problems. Among them, impurities entering the oil is the number one cause of lubrication failure, followed by water. These two contaminants are problems that may be encountered in any application occasion. Therefore, impurities and water must be strictly prevented from entering the oil.
Holdmeyer emphasized: "The wisest way is to prevent water and impurities from entering the lubricating oil from the source, with prevention as the main focus. Preventing impurities from entering the oil certainly requires some investment, such as purchasing breathing caps and using high-efficiency seals, but once impurities enter the oil, it takes about 10 times the money to get them out. In other words, if "pollution prevention" costs 1 yuan, "pollution treatment" costs about 10 yuan."
Three major ways for lubricants to be contaminated:
To ensure the cleanliness of lubricants, which links should be started? Holdmeyer said that the storage, packaging and use of lubricants are the three basic links of pollution control.
l Lubricant storage: In actual operation, lubricant contamination is usually such a situation: the equipment manufacturer specifies the ISO cleanliness level that the lubricant needs to reach for the user, and the user purchases lubricants that meet the corresponding standards according to the specified level. After the oil products are transported, they are stored in the warehouse, but some users store them outdoors. Because the users do not pay attention to sealing the oil products, or water accumulates on the top of the oil barrel, the lubricating oil absorbs moisture or impurities during the storage process.
l Repackaging: The lubricating oil may also be contaminated during the repackaging process. The tools such as oil barrels, oil pots or funnels used by users are not clean, and there may even be old oil left inside the container, or different oil products share a container or tool, causing the new oil to be contaminated.
l Oil use: Lubricating oil may also be contaminated during the oil use process. For example, if the equipment vent is not equipped with a breathing cap (also known as a breathing cap or respirator), impurities, dust, and moisture in the atmosphere enter the lubrication system from the vent; if the oil tank is not covered well, impurities enter the oil tank; if the oil tank is rusty, rust residue falls off and enters the lubrication system; if the seal is not tight, moisture and impurities enter the oil, etc. Because lubricating oil is hygroscopic and absorbs moisture in the atmosphere, the equipment vent should be equipped with a breathing cap with a drying and dehydrating function.
To extend the service life of lubricants and equipment and reduce lubrication failures, it is necessary to prevent the lubricants from being contaminated during use. First of all, written operating specifications should be formulated for the storage, subpackaging and use of lubricants.
Holdmeyer gave several suggestions for the storage of lubricants. First of all, the lubricating tools used should be properly stored and used for specific purposes. Store various lubricating tools indoors and keep the room clean and tidy. If conditions permit, try to choose to store oil products indoors. Because the temperature difference outdoors is greater than that indoors, the sun is exposed during the day and the temperature drops at night. The repeated large temperature difference changes are not conducive to the stability of lubricant additives. Large temperature differences also make it easy for lubricants to absorb moisture in the air. Outdoors are also prone to sun and rain. If the oil barrel is placed vertically, water is easy to accumulate on the top, causing the lubricant to be contaminated by water. Therefore, when storing lubricants outdoors, they should be covered with waterproof cloth to prevent sun and rain. It is best to place the oil barrel horizontally or tilt it sideways to prevent water from accumulating on the top of the barrel.
During the subpackaging and filling of lubricants, it is necessary to use specific instruments for specific purposes, and the tools that are reused should be cleaned in time to ensure that they are clean and dry for the next use. It is best to arrange a room to store the large iron barrels, plastic barrels, oil dispensers, and related tools used for oil transportation. Holdmeyer also recommends that the refueling and dispensing tools used be distinguished by plastic labels of different colors. The rags used should be clean and not easy to shed, and the trash cans should be covered.
During the refueling process, it is recommended to use a small mobile filter refueling truck. This refueling truck has a fuel tank, a built-in filtration system and a refueling pipe, which can filter the oil before adding it to the equipment. The filtration accuracy of the refueling truck can be selected according to the required ISO cleanliness level. In order to avoid adding the wrong oil, in addition to labeling the equipment, oil barrels, and various refueling tools, different refueling port connectors can be used. Specific lubricants are installed with specific refueling port connectors to avoid misuse of oil.
The choice of oil packaging is particular:
Oil will slowly oxidize after contact with air, so the oil will oxidize and deteriorate after long-term use after opening. Oversized oil storage tanks may not be suitable. If the amount of oil used is small or the number of times it is used is small, there is no need to use large barrels of oil, because the remaining oil will be retained in large quantities. If stored for a long time, the lubricant will not be fresh enough when it is used. "If the amount of lubricant used and the use of the lubricant are more suitable for lubricants packaged in small barrels, then the ISO cleanliness of the lubricant shipped from the large barrel or oil tank must be ensured to meet the standard, and it must also be filtered when it is divided into small barrels. Large oil tanks should be equipped with dry breathing caps (vent caps) to prevent dust, impurities, water and moisture from invading. Holdmeyer said: "The oil tanks used to store lubricants should be sampled and tested at least once a year, and cleaned at least once a year to prevent moisture or impurities from contaminating the oil tanks. If there are no conditions to do these things, at least flush the oil drain port and visually inspect it. ”
We have emphasized before that it is important to take measures to prevent impurities in lubricating oil from entering the oil. To do this, we must first know where the contaminants in the oil come from. Are these impurities generated by the equipment, or are they brought in during storage? Or are they brought in when collecting oil samples? Are the oil products not sealed properly? We must fully consider various possible reasons to effectively cut off the source of pollution from the source.
"Although these are small details and not high-tech, there are many cases where these details are not done well, such as a simple oil tank not covered properly." Holdmeyer said, "Whether it is during daily maintenance of equipment operation or during the process of adding lubricating oil, contaminants may be introduced into the lubricating oil. At any time, the lubricating oil in the oil barrel should be filtered before adding it to the equipment. "
Hydraulic equipment is very sensitive:
"Although all equipment is very taboo about water or other impurities in the oil, hydraulic equipment is particularly sensitive to impurities, and the adverse consequences of impurities will occur quickly. "Holdmeyer said, "Because the gaps between hydraulic equipment parts are generally very small, for example, the gaps between servo valves are only 1 to 4 microns. What does such a small size mean? The particles of talcum powder are about 10 microns, and the size of bacteria is 2 to 3 microns." In order to prevent tiny impurities from getting stuck between parts, we must allow the impurities to pass through the gaps between parts smoothly. To do this, hydraulic equipment manufacturers specify the ISO cleanliness level of lubricating oil for users. The ISO cleanliness level specifies the size of impurity particles allowed by the equipment (4 microns, 6 microns, 14 microns) and the number of particles. If the particle count exceeds the specified ISO cleanliness level, the user must immediately take oil cleaning measures or replace the oil. The ISO cleanliness level requires the detection of the number of particles of three sizes: 4 microns, 6 microns, and 14 microns, but some hydraulic equipment manufacturers specify the detection of two of the particles, such as Caterpillar .
Holdmeyer reminds users that if impurities in the hydraulic oil are not removed in time, it will cause wear of the hydraulic valve, leading to a series of faults such as slow response, blockage and jamming of the hydraulic valve, metal corrosion on the valve core surface, burning of the solenoid valve, and failure of the safety system. Impurities can also cause wear of the hydraulic cylinder, especially for construction machinery. Because construction machinery is easily contaminated with dust and impurities, damage to the piston rod and seal is the main reason for the entry of impurities. Observe the piston rod when it comes out of the cylinder. If you find oil on it, then check it.
The first line of defense - filtration:
For most equipment, the lubricating oil filter is the first line of defense for oil. According to Pall Corp., Holdmeyer said that good filtration combined with proper oil maintenance can extend the service life of oil pumps and equipment by 4 to 10 times! Rolling bearings can even extend their service life by 50 times. Other benefits include extending the service life of oil products, and reducing the cost of purchasing new oil, changing oil, and disposing of waste oil.
Users will find that all filters or filtering equipment have filtration accuracy, but I would like to say that filtration accuracy can sometimes be misleading. "If the filter is marked with a nominal rating, then this accuracy does not mean anything, because the nominal rating is just a one-time arbitrary value given by the manufacturer and may not be reliable in use. If you see the nominal rating given by the filtering equipment, then the user should question its filtering effect." Holdmeyer affirmed, "Users should pay attention to the absolute rating of the filter. The absolute rating shows the maximum size of the filter hole and how large the particles can pass through the filter element."
Holdmeyer continued: "In addition to absolute accuracy, there is another important indicator of the filter, which is the filtration ratio, that is, the Beta Ratio (β value). The filtration ratio = the number of particles of a certain size before filtration / the number of particles of the same size after filtration. Let's give an example to illustrate. If the number of 6-micron particles in the oil upstream of the filter is 1 million, and after filtration, the number of 6-micron particles in the oil downstream of the filter is reduced to 500,000, then the β value is 2 and the filtration efficiency is 50%. If the 1 million particles are reduced to 1,000, then the β value is 1,000 and the filtration efficiency is 99.9%. [Note: The conversion formula between the filtration efficiency (%) of the filter element and the β value is: ((β value-1)/β value) x 100. ]
According to our experience, high-pressure equipment has higher requirements for oil cleanliness. High-pressure equipment has stricter control requirements for oil flow, and higher requirements for the speed and accuracy of the control valve, so the requirements for oil cleanliness are also stricter, because the equipment clearance is more precise, and impurities in the oil are more likely to cause equipment failure. Compared with low-speed sliding bearings, high-precision rolling bearings have more stringent requirements for the cleanliness level of lubricating oil.
Hazards of water:
Next, Holdmeyer talked about the hazards of water to lubricating oil. Water is the second culprit of lubrication failure. Only 400ppm of water in the oil can reduce the life of rolling bearings by up to 85%. Common sources of water are moisture in humid atmosphere, condensation caused by temperature drop, storage of lubricating oil in oil tanks, and some water dissolved in the oil in the oil tank. Water gun flushing and flushing are also common causes of water ingress, as well as cooling water leakage, oil seal damage or improper installation.
Visual inspection and laboratory instrument testing are both It can be found that water has entered the oil. The latter is more accurate and can also find less dissolved water. Another method is the heating method. The general practice is to heat the lubricating oil on an iron sheet. If a crackling or popping sound is heard, it means that there is water in the oil.
Holdmeyer said that during the on-site inspection, he found that in many cases, everyone thought it was a closed circulation lubrication system, but water actually entered. The reason lies in some very small details, such as cracked oil mirrors, leaking seals, etc. Sometimes it is not done correctly when adding or draining oil. New oil is added without filtering, and water or impurities in the oil are added. In some cases, the vents of the equipment are not equipped with effective air filters, or the old-fashioned covers are not sealed, resulting in impurities in the atmosphere and moisture in the air entering the equipment. It is recommended to use a breathing cap with a desiccant to effectively isolate impurities and moisture in the air.
Holdmeyer finally concluded: "To lubricate the equipment well, the lubricating oil must be kept clean and free of water. Users must ensure that the oil is clean before adding it to the equipment. Store lubricating oil and grease properly, keep the oil clean during use, and do not use dirty, linting rags to wipe grease fittings or oil filler ports.
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