Servicing Air Compressor: How To Do a Routine Cleaning?


During the operation of air compressor, the impurities in the air and the sludge, carbon deposits and other deposits inside the air compressor will seriously affect the working efficiency of the compressor, resulting in a decrease in the heat dissipation and energy efficiency of air compressor. In severe cases, it will cause compressor equipment failure and even cause accidents such as shutdown. Therefore, cleaning and maintenance of air compressors are essential for users.

Servicing Air Compressor How To Do a Routine Cleaning

There are two ways to clean dirt from air compressor: Physical cleaning and Chemical cleaning. When cleaning an air compressor, make sure the compressor is shut down and the inside pressure is released, and turn off the main power supply.

After cleaning, make sure that all components of the air compressor are installed properly and do not miss any part.

Clean the air filter

clean Clogged air filter

Importance of air filter

The air filter is very important for the normal operation of the air compressor. Once the air filter is clogged, it will cause:

  1. Compressed air pressure drops: The normal operation of the air compressor requires a certain air pressure. Once the air filter is clogged, it will limit the speed at which air passes through, making the pressure drop.
  2. Energy consumption increasing: If the air filter is clogged, will lead the air compressor to have a lower working efficiency. In order to maintain normal working pressure, the air compressor needs more energy supply. This will increase energy consumption and increase production costs.
  3. Air quality decreasing: The main function of air filters is to filter dust, particles and other impurities in the air to ensure air cleanliness. Once the filter is clogged, unfiltered air will enter the production environment, affecting the air quality of the production environment, and ultimately causing adverse effects on product quality and may even affect the health of employees.
  4. Equipment damage accelerating: A clogged air filter will cause the air sucked in by the air compressor to contain more impurities, such as dust, sand, etc. These impurities will enter the internal mechanical system of the air compressor, accelerating the wear and damage of the equipment.(Look at how and where to service air compressor)

How to clean air filter

The air filter is equipped with a differential pressure switch. When the differential pressure switch setting value is reached, the differential pressure switch is activated, or when the internal setting time is zero, the LCD screen will display that the air filter is blocked, indicating that the air filter must be cleaned or replaced. Maintenance should be performed after the air compressor is shut down and the corresponding safety measures are taken.

The specific methods are as follows:

Open the end cover, take out the filter element, loosen the air filter element fixing bolts, check the air filter element for blockage, use compressed air to blow from the inside to the outside to clean the accumulated dust, and note that the pressure of the compressed air should not exceed 0.3MPa.

If the air filter element is damaged, it should be replaced. To check whether the air filter is damaged, you can place a light inside the air filter element and observe whether there is light exposed from the outside; in addition, if the surface of the filter element is stained with oil, a new air filter element should be replaced; cover the end cover after cleaning or replacing the filter element.

Check that the differential pressure switch equipped with the air filter element is normal, and the pre-set value does not exceed 50kPa. It is best to clean the air filter once a week.

When reinstalling the air filter, the sealing ring at the front end should fit tightly against the inner end face of the air filter housing.

The maintenance of the diesel engine intake air filter of the diesel-powered screw machine should be carried out simultaneously with the air compressor air filter, and the maintenance method is the same.

The air filter is normally replaced every 1000-1500 hours. For places with particularly harsh environments, such as mines, ceramic factories, cotton mills, etc., it is recommended to replace the air filter every 500 hours.

When cleaning or replacing the air filter, the parts must be matched one by one to prevent foreign matter from falling into the intake valve. Usually, you must regularly check whether the intake telescopic tube is damaged or flattened, and whether the connection between the telescopic tube and the air filter intake valve is loose or leaking. If found, it must be repaired and replaced in time.

Clean the oil filter

The cleaning and maintenance of the oil filter should be carried out after the air compressor is shut down and the corresponding safety measures are taken, as follows:Clean Clogged oil filter

Use pliers to unscrew the old filter and clean the contact surface. Apply a thin layer of oil film on the surface of the new filter seal. Tighten the new filter by hand until the gasket is sealed; special attention should be paid to not using other tools except your hands when tightening the new filter to prevent it from being difficult to remove when replace at next time.

Check that the differential pressure switch equipped with the oil filter is installed normally, and the preset value is 150kPa. The oil filter should be replaced after the first 500 hours of operation of the new machine.

Use a special wrench to reverse the oil filter element to remove it. It is best to add screw oil before installing the new filter element. The filter element seal should be screwed back to the oil filter seat with both hands and tightened firmly.

It is recommended to replace the new filter element every 1500-2000 hours. It is best to replace the oil filter element at the same time when changing the engine oil. The replacement cycle should be shortened when used in harsh environments.

It is strictly forbidden to use the oil filter beyond the expiration date. Otherwise, due to serious blockage of the filter element, the pressure difference exceeds the tolerance limit of the bypass valve, the bypass valve automatically opens, and a large amount of dirt and particles will directly enter the screw host with the oil, which will cause serious consequences.

Clean the oilgas separator filter

Maintenance should be performed after the air compressor is shut down and appropriate safety measures are taken. Small air compressors mostly use rotary oil-gas separator filter elements, and their maintenance methods are the same as oil filters; the cleaning steps of the built-in type are as follows:Clean compressor oil-air separator

Loosen the pipeline on the oil and gas barrel, and remove the pipeline from the outlet of the pressure maintenance valve (minimum pressure valve) to the after-cooler, remember their position and order, and ensure that they can be correctly reinstalled later; loosen and remove the return oil pipe; loosen the fastening bolts of the oil and gas barrel cover; remove the oil cover; take out the oil and gas separator filter element, and replace the new oil and gas separator filter element and gasket.

Reinstall according to the opposite steps and tighten the bolts with a torque wrench. After the machine is turned on, re-tighten the bolts of the oil and gas barrel cover. Check that the differential pressure switch equipped with the oil and gas separator filter element on the oil and gas barrel is installed normally, and the preset value is 100kPa. The oil-gas separator is a component that separates the screw lubricating oil from the compressed air.

Under normal operation, the service life of the oil-gas separator is about 3,000 hours, but the quality of the lubricating oil and the filtration accuracy of the air have a huge impact on its life. It can be seen that the maintenance and replacement cycle of the air filter must be shortened in harsh use environments, and even the installation of a pre air filter could be considered.

The oil-gas separator must be replaced after it expires or the pressure difference between the front and rear exceeds 0.12Mpa. Otherwise, the motor will be overloaded, and the oil-gas separator will be damaged and leak oil.

Replacement method:

Remove the control pipe joints installed on the oil and gas barrel cover; remove the return oil pipe on the oil and gas barrel cover that extends into the oil and gas barrel, remove the fastening bolts of the oil and gas barrel cover; remove the oil and gas barrel cover and take out the oil fine separator. Remove the asbestos pad and dirt stuck on the upper cover; install a new oil fine separator, note that the upper and lower asbestos pads must be stapled, and the asbestos pads must be placed neatly when pressed, otherwise it will cause pad impact; finally, reinstall the upper cover, oil return pipe, and control pipes as they were, and check if there are air leaks.

Clean or replace the air compressor oil

Screw Air Compressor Filtration Flow Chart

The quality of air compressor oil has a decisive influence on the performance of the air compressor. Good oil has good antioxidant stability, rapid separation, good foam removal, high viscosity, and good anti-corrosion performance.

The first oil change is carried out after 500 hours of running-in period of the new machine, and new oil is replaced every 2000 hours of operation thereafter. It is best to replace the oil filter at the same time when changing the oil. Use in places with harsh environments to shorten the replacement cycle.

Replacement method:

Start the air compressor and run it for 5 minutes to raise the oil temperature to above 50℃C, and the oil viscosity decreases.

Turn off the air compressor. When the pressure in the oil and gas barrel drops to 0.1Mpa, open the drain valve at the bottom of the oil and gas barrel and connect the oil storage tank. The drain valve should be opened slowly to prevent the lubricating oil with a certain pressure and temperature from splashing. Wait until the lubricating oil is in the form of drops and then close the drain valve. Unscrew the oil filter, drain the lubricating oil in each pipeline at the same time, and replace the new oil filter; open the oil filler cap, inject new oil, make the oil level within the oil mark scale range, tighten the oil filler cap, and check for leakage.

Lubricating oil must be checked frequently during use. If the oil level line is too low, new oil should be added in time. Condensed water must also be discharged frequently during the use of lubricating oil. Generally, it should be discharged once a week, and once every 2-3 days in high temperature climates. If the machine is shut down for more than 4 hours, open the oil drain valve without pressure in the oil and gas barrel to drain the condensed water, and quickly close the valve when you see organic oil flowing out.

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Lubricating oil is strictly prohibited from mixing different brands, and lubricating oil should not be used beyond the expiration date, otherwise the quality of the lubricating oil will deteriorate, the lubricity will be poor, the flash point will be reduced, and it is very easy to cause high-temperature shutdown and cause the oil to spontaneously combust. Know more about or determine whether you’re using lubricating oil improperly, please refer to our previous article:(5 Misunderstandings About Industrial Oil Lubricants Used in Air Compressors

Are you looking for a reliable and efficient power source for your industry? Kotech dealers are experienced in finding the perfect air compressor for your needs.

Contact your local Kotech dealer today and discover how an air compressor can increase your productivity and safety.

Clean the cooler

Water-cooled air compressors are widely used in large projects because of their low dependence on the environment and stable heat dissipation. However, if the cooling water quality is poor and the hardness is high, the cooler will easily scale on the tubes after long-term operation, affecting the cooling effect.

The cooler used in the screw air compressor is a shell and tube type. After removing the parts of the air compressor inlet and outlet pipes, you can use a brushing tool to clean out the scale in the pipes. This method is only suitable for air compressors with less severe scale.

kotech teach you how to Clean the cooler

If the scale inside the air compressor cooler is serious, it needs to be cleaned with the help of chemical reaction. Using chemical cleaning will not affect the quality of the air compressor cooler, so you can use it with confidence.

Scale is an alkaline substance, and a special scale cleaning agent (acid cleaning) can be used to clean the dirt attached to the tubes. Then use dilute hydrochloric acid to dissolve the scale. However, the acid content cannot be too high, otherwise it will corrode the metal.

When cleaning in summer, attention should be paid to the temperature of the cleaning liquid, which should not exceed 60°C. The best cleaning temperature is 30~50°C; generally, cleaning takes about 6 hours.

If cleaning in winter, the solution can be heated to 70-80 degrees to speed up the cleaning speed and improve the cleaning effect. After cleaning with dilute hydrochloric acid solution, drain the liquid and rinse with clean water. In order to prevent acid corrosion, the cooler can be circulated and cleaned with 5% soda solution for 10 minutes, and finally rinsed again with clean water.

It is recommended to clean the air compressor at least twice a year, because in the air compressor operation test, the cooling effect of the cleaned air compressor will be greatly improved.

When cleaning the air-cooled cooler, open the air duct to clean the cover, or remove the cooling fan; use compressed air to blow the dirt off, and then take the dirt out of the air duct; if it is dirty, spray some degreasing agent and blow it again. When the screw air compressor cannot be cleaned with the above method, the cooler needs to be removed, soaked or sprayed with cleaning liquid and cleaned with a brush (wire brush is strictly prohibited).

Generally, the operating temperature of the air compressor will drop by about 10 degrees after cleaning the cooler.

The intake valve is clogged will cause the air compressor to start with load

Clean the intake valve

If the dirt on the intake valve is serious, a new cleaning agent should be used during cleaning. During the cleaning process, the cleaner parts should be cleaned first, and the parts with more dirt should be cleaned later. The cleaned parts should be rinsed again with clean water to avoid corrosion and shortening the service life of the parts. The parts washed with clean water should be placed in a clean place to dry to avoid rusting of iron-containing parts.

When cleaning the valve plate and the place where the valve body contacts the valve plate, attention should be paid to the flatness of the surface, and it should be cleaned and replaced if necessary, otherwise it will cause the air compressor to start with load (the large screw air compressor unit will fail to start when starting with load).

Clean the minimum pressure valve

Although the minimum pressure valve in air compressor looks small, do not underestimate it, it controls the entire machine. The structure of the minimum pressure valve is very simple. You can take out the components inside by unscrewing the nut between the valve core and the valve body. The minimum pressure valve core of the small unit is built into the valve body. You can take out all the internal components by disassembling the valve body cover. The cleaning method of the minimum pressure valve is the same as the cleaning method of the intake valve.

Clean oil return check valve

The function of the oil return check valve is to smoothly return the oil from the oil-gas separator to the main engine without letting the oil from the main engine flow back to the oil-gas separator. The oil return check valve has a connection on the valve body. Unscrew it from this point, take out the spring, steel ball, and steel ball seat. Some air compressors have a filter inside the check valve. After that, clean it with a cleaning agent and put it back into the air compressor.


Through the above maintenance and care measures, you can ensure the long-term stable operation of your air compressor, reduce the failure rate and improve production efficiency. At the same time, purchasing high-quality air compressor accessories, such as lubricating oil, filters, etc., is also the key to ensure the performance of the air compressor. Also, regularly invite professionals to inspect and maintain to ensure the safe operation of the air compressor is a good idea.

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