Several “common problems” common to air compressor maintenance personnel

1. Unable to correctly judge and analyze faults, it is common to blindly disassemble

Because some maintenance personnel are not clear about the structure and principle of the compressor, they do not carefully analyze the cause of the failure, and cannot accurately judge the location of the failure. New problems arose due to poor maintenance skills and workmanship. Therefore, when the machinery breaks down, it must be detected by testing equipment. If there is no testing equipment, traditional fault judgment methods and means such as “asking, looking, checking, and testing” can be used to determine the fault in combination with the structure and working principle of the compressor. The area most likely to fail.

When judging compressor faults, the “elimination method” and “comparison method” are generally used. Follow the order from simple to complex, first appearance, then interior, first assembly, and then parts. “.

The reason is that such people still lack the systematic learning and training of compressors and related electrical and mechanical knowledge systems, lack of understanding of compressor operation processes and correlations, and blindly take one step at a time.

2. The phenomenon of “replacement and repair” exists to varying degrees

It is relatively difficult to judge and eliminate compressor faults. Some maintenance personnel have always used the method of replacing parts for testing. Replace parts that should not be replaced at will, which increases the user’s expenses.

There are also some faulty parts that can be repaired to restore their technical performance, and can be repaired without complicated repair processes, but maintenance personnel require users to replace new parts, blindly adopting the method of “replacement and repair”, resulting in serious waste.

The above-mentioned practice of blindly changing parts and blindly replacing repairable parts still exists to varying degrees in some repair units. During maintenance, the cause and location of the failure should be carefully analyzed and judged according to the failure phenomenon, and repair methods should be adopted for repairable parts to restore performance, and the practice of blindly replacing parts should be avoided.

In addition, many of the replaced spare parts can be repaired and reused after new processes such as brush plating and spraying, but in actual work, maintenance workers are generally unwilling to perform maintenance. There are many reasons why maintenance personnel are unwilling to repair damaged equipment: one is the lack of necessary maintenance tools. It is necessary to be equipped with appropriate special disassembly tools and measuring instruments; electricians must be equipped with accurate digital multimeters, regulated power supplies, testers and other tools. Without these tools, maintenance workers can only do nothing. The second is the lack of corresponding incentive mechanism. The maintenance workers worked hard to restore a spare part with a higher price, but they did not receive any encouragement or reward. Over time, the maintenance workers gradually lost their enthusiasm for repairing and reusing waste parts. Therefore, incentive measures should be taken, depending on the price of spare parts, reuse value, reliability, etc., to reward the personnel who repair the spare parts with the percentage of the original spare part price, and link it with monthly and annual performance to encourage maintenance personnel The enthusiasm for the restoration and reuse of waste parts.

3. The quality of new parts is not checked, and failures after assembly are more common

Before replacing parts, some maintenance personnel do not conduct technical inspection on the new parts, and install them directly on the compressor after they are brought, which is unscientific. At present, the quality of spare parts sold in the market varies, and some fake and shoddy parts are misleading; some parts have changed performance due to long storage time, and if they are not tested, they often cause failures after assembly.

Before replacing new accessories, necessary inspection and testing must be carried out. The inspection includes appearance and performance tests to ensure that the new accessories are fault-free and prevent unnecessary troubles caused by them.

4. Replacement or misuse of accessories is more common, accommodating users, and overflowing with inferior products

When repairing compressors, replacement or misuse of parts is still common. Emergency replacement of some parts is feasible, but long-term use is harmful and will affect the safety and technical performance of the machine.

Some maintenance personnel do not know much about the mechanical structure and principle, and many spare parts do not match the models, but they think that as long as they can be installed, they do not consider whether the technical performance of the equipment can be exerted. Therefore, when repairing the compressor, you should try to use the original type of accessories, and you cannot use other types of accessories as substitutes, let alone misuse them.

In order to meet the low price requirements of customers and win orders, some people often use inferior products. Counterfeit and inferior products are indeed cheap, but the losses outweigh the gains for users. For example, air compressor lubricating oil, long-term use of inferior air compressor oil will cause early wear and tear on the surface of the rotor and various parts, and it will also increase fuel consumption and reduce the working efficiency and performance of the air compressor. Inferior air compressor oil can easily lead to oil filter and oil clogging because the quality does not meet the standards. If you want the low-quality oil separator to achieve the genuine filter effect, you must increase the filter area, but this will easily increase the energy consumption of the compressor, and the poor-quality oil separator is prone to explosion accidents due to poor conductivity. The oil filter with poor filtering effect cannot filter out the dust and impurities in the air. The dust will enter the rotor with the lubricating oil, causing bearing wear and reducing efficiency. Due to quality problems, the inferior oil filter may easily cause the filter to burst during work.

5. The maintenance method is irregular, and “fixing the symptoms but not the root cause” is still the usual method

When repairing compressors, some maintenance personnel do not take correct maintenance methods, thinking that emergency measures are omnipotent, replacing “maintenance” with “emergency”, and there are still many phenomena of “fixing the symptoms but not the root cause”.

The only way to deal with over-temperature shutdown is to clean the cooler and change the oil. This method is very effective for new machines. But for old machines more than two years old, it is a temporary solution, not a permanent cure. Often just after cleaning, the phenomenon of over-temperature shutdown occurs again. In this case, we always suspect that the cooler was not cleaned thoroughly enough. But is this the real reason? In fact, it is not the case that the incomplete cleaning of the cooler is only one reason. However, there is a huge hidden danger of overheating in the oil circuit system of the machine. Most of the current screw air compressors use mineral oil or semi-synthetic oil based on mineral oil, and the service life is generally between 2000-4000 hours. This kind of oil will usually coke after about two years of operation. This phenomenon will occur even in normal oil changes, because it is impossible to discharge 100% of the sink oil clean every time the oil is changed. The remaining sinking oil is deposited at the bottom of the gearbox and other low points in the oil circuit, and then participates in the oil cycle along with the new oil. Running for a certain period of time will cause oil quality to deteriorate and cause coking. Green or blue discharge liquid will be discharged from the sewage outlet of the air compressor. When the oil is changed, the oil viscosity will be very high, and asphalt-like lumps will be discharged. If it continues to run, it will be difficult for the machine to start cold, and the motor is often overloaded. In the worst case, the main engine may even fail to rotate, resulting in false locking.

The internal gas cooling of the air compressor is water-cooled. At the initial stage of use, the cooling water connected is tap water. After a period of operation, the gas cooling effect will decline. The main reason is that the wall of the cooling water system is scaled or blocked. Forward and reverse flushing with high-pressure water has a certain effect, but it is still not ideal. After repeated rinsing with descaler, it works well. However, the descaling agent has strong acidity, which will corrode the pipe wall of the cold water system. Frequent flushing will make the pipe wall thinner, which will affect the pressure resistance and service life of the pipe, thus treating the symptoms rather than the root cause. The most effective method is to deal with the causes of scaling and blockage. Since the tap water is easy to scale, the cooling water is changed to softened water that is not easy to scale, and a filter is installed at the inlet of the cooling water, and the filter is cleaned regularly. In this way, maintenance is simple and convenient, while reducing the failure rate of equipment and prolonging the service life of the system.

The “welding instead of repair” that is often encountered is also an example. Some parts can be repaired, but some maintenance personnel often use the method of “welding to death” in order to save trouble. When installing the piston pin, the piston pin is directly driven into the pin hole without heating the piston, resulting in an increase in the deformation of the piston and an increase in ellipticity; when the motor is repaired, the bearing bush is scraped excessively, and the friction-reducing alloy layer on the surface of the bearing bush is scraped off, resulting in Early wear occurs due to direct friction between the steel back of the bearing bush and the crankshaft; when disassembling the interference fit parts such as bearings and pulleys, do not use a tensioner, and hit hard, which may easily lead to deformation or damage of the parts; use new pistons, cylinder liners, and fuel injection nozzle components , plunger assembly and other parts, use fire to seal the oil or wax on the surface of the parts, so that the performance of the parts will change, which is not conducive to the use of the parts. When it is found that the pressure at the end of the pipeline or the pneumatic equipment is insufficient, the working pressure of the system is blindly increased without checking the cause of the failure, resulting in too high system pressure, which is easy to damage valves and pipelines; Artificially increase the fuel supply of the fuel injection pump and increase the fuel injection pressure of the fuel injector.

These irregular maintenance methods can only be used for emergency, but they cannot be used for a long time. The cause of the failure must be found out fundamentally, and formal maintenance methods should be adopted to eliminate the failure, which should attract the attention of maintenance personnel.

6. Don’t pay attention to the quality of “small parts”, because “small” loses “big”, resulting in increased failures

During maintenance work, some maintenance personnel often only pay attention to the maintenance of the machine head, three filters, and motors, but ignore the maintenance of “small parts” such as various valves, various instruments, and pipelines. They think that these “small parts” As long as it doesn’t affect the stable gas production, it doesn’t matter even if it is damaged, as long as the machine is active, it can make do with it. As everyone knows, it is these “little parts” that lack maintenance, which leads to early wear and tear of machinery and shortens its service life.

For example, the water temperature gauge, oil temperature gauge, oil pressure gauge, sensor, alarm, fan hood, bolts and nuts used by the compressor, these “small parts” are essential for the normal operation and maintenance of the compressor. It is very important to prolong the service life of the machine. If you do not pay attention to the maintenance during the maintenance work, you will often “make a small fortune” and cause the compressor to fail.

7. Maintenance taboos are forgotten, hidden faults occur frequently

When repairing the compressor, some maintenance personnel do not understand some problems that should be paid attention to during maintenance, which leads to frequent “habitual” mistakes in disassembly and assembly, which affects the quality of maintenance.

For example, disassembly and assembly of the hot car will lead to deformation and cracks of the equipment; when installing the piston pin, the piston pin is directly driven into the pin hole without heating the piston, resulting in increased deformation and ellipticity of the piston; copper is added to the back of the crankshaft main bush or connecting rod bush Pads or paper pads are easy to block the oil passage, leading to shaft burning accidents; excessive scraping of the bearing pads, the friction-reducing alloy layer on the surface of the bearing pads is scraped off, resulting in early wear and tear due to direct friction between the steel back of the bearing pads and the crankshaft; excessive removal of bearings, pulleys, etc. Do not use a tensioner when fitting parts, hard knocking will easily lead to deformation or damage of parts; when unpacking new parts, use fire to burn the oil or wax sealed on the surface of the parts, which will change the performance of the parts, which is not conducive to the use of parts .

8. There are a lot of compressor problems, if you don’t pay attention to the details, there will be hidden dangers in maintenance

The failure is also dealt with, and different final results will be brought about due to different personnel and technical capabilities, and the differences often come from some details:

The mixed use of lubricating oil of different grades leads to deterioration of the lubricating oil; before starting the air compressor, it is not confirmed whether the rotation direction of the motor is consistent with the specified direction, resulting in the reverse rotation of the air compressor, the pressure cannot be established in the pump head, and the rotor has no lubricating oil, so it cannot be used The heat generated by friction in the pump head is taken away by the circulation of lubricating oil, and the heat is accumulated in an instant to generate high temperature, which deforms the inner screw and the shell of the main engine, and the female and male screws bite and lock. The end face of the rotor and the end cover are stuck together due to high temperature, resulting in severe wear of the end face of the rotor, and even the defect of parts, resulting in damage to the gearbox and rotor. Make changes or add devices to the air compressor that affect safety and reliability at will; disassemble high-temperature components after the temperature is cooled to the ambient temperature; run the air compressor under the condition of exceeding the specified pressure and temperature; when doing debugging work , The air compressor suction port is blocked during operation; after maintenance and before starting up, it is not confirmed that all safety devices have been reinstalled, and the tools have been removed from the air compressor.

There are many Ma Daha-type maintenance personnel in the industry, and the details that are often forgotten are precisely the crucial links.

9. Incomplete decontamination and cleaning of parts, premature wear and corrosion often occur

When repairing the compressor, it is of great significance to correctly remove the oil and impurities on the surface of the parts to improve the repair quality and prolong the service life of the machine. Due to inadvertently strengthening the cleaning of parts, unreasonable selection of cleaning agents, and improper cleaning methods, etc., early wear and corrosive damage of parts have occurred in some repair units. During the overhaul of the compressor, the oil or impurities accumulated in the water-gas separator, intake valve, minimum pressure valve, unloading valve, oil return check valve, temperature control valve, lubricating oil passage, etc., will prevent maintenance work from occurring. Thoroughly, reduce the trouble-free running time of the compressor.

Precautions for maintenance personnel when cleaning parts:

(1) To choose the cleaning agent correctly

For the cleaning of various parts, different cleaning agents should be selected correctly according to their different requirements for cleanliness;

(2) To prevent corrosion and rust of parts

In order to ensure the quality of parts, corrosion and rust of parts should be prevented, especially for precision parts, any degree of corrosion or rust is not allowed. Therefore, when cleaning, do not use alkaline cleaning agents (especially strong alkaline cleaning agents) to clean aluminum alloy parts, and do not use strong acid cleaning agents to clean copper parts to minimize corrosion of parts;

(3) Different parts should be cleaned separately

Aluminum alloy parts and copper parts should not be cleaned together in alkaline or acidic cleaning agents. Rubber parts should not be cleaned together with other steel parts in gasoline, diesel, acid or alkaline cleaning agents.

For a long time, traditional cleaning methods such as mechanical methods (scraping, brushing), high-pressure water, chemical cleaning (pickling), etc. have caused many problems when cleaning air compressors: they cannot completely remove scale and other deposits, and cause corrosion to equipment. Residual acid causes secondary corrosion or under-scaling corrosion on materials, which eventually leads to replacement of equipment. In addition, cleaning waste liquid is toxic and requires a lot of money for wastewater treatment. It is recommended to choose a special air compressor cleaning agent.

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