After a hydraulic system has operated for a period of time, contaminants will gradually accumulate in the filter, affecting the stability and service life of the system. To keep your hydraulic system running properly, you need to maintain the filter regularly. In this article, I’ll describe when hydraulic filters need to be cleaned, the proper way to clean hydraulic filters, and the possible risks involved in the cleaning process. In addition, I will tell you when hydraulic filters can be cleaned and when they should be replaced, and help you to make a more secure decision.
When Should You Clean a Hydraulic Filter?
In most cases, we do not clean hydraulic oil filters. Filters should only be cleaned if specific conditions are met.
The conditions under which cleaning can usually be considered include:
- You are using a reusable filter, not a disposable cartridge.
- The circuit that the filter is in does not affect the core function of the system.
- Cleaning is only to temporarily bring the equipment back into operation, not for long-term use.
- The filter is only lightly contaminated, and the system is currently operating normally.
Situations in which cleaning is not generally recommended include:
- The system requires a high degree of stability and cleanliness in operation.
- The equipment needs to run continuously, and the cost of downtime is high.
- It is impossible to confirm whether the filtration effect is still up to standard after cleaning.
- The filter element has been seriously clogged, deformed or damaged.
Which Types of Hydraulic Filters Can Be Cleaned — and Which Cannot
When judging whether the hydraulic filter can be cleaned, you should look at the structure and material of the filter element, not just to see whether the appearance is dirty or not.
Filter element that can be cleaned:
Metal mesh filter element: It has a sturdy structure and is not easily damaged by repeated cleaning.
Engineering plastic filter element: It is special for some industrial equipment and can be safely cleaned.
Filter element that is not recommended to be cleaned:
Paper filter element: It is easy to break, and the filtering effect will be reduced after cleaning.
Fibreglass or composite material cartridge: It is made of a fragile material and is easily damaged after cleaning.
Disposable cartridge: it is meant to be replaced; there is no need to clean it.
How to Clean a Reusable Hydraulic Filter Step by Step
The following steps only apply to reusable hydraulic cartridges. If your cartridge does not support cleaning, do not follow these steps.
Step 1: Shutdown and safety preparation
First, you should stop the equipment from running and make sure the hydraulic system has been completely depressurised to avoid oil spraying out during disassembly.
You should perform the cleaning in a clean working environment to prevent dust from entering the filter element.
At the same time, you should wear basic protective equipment, such as gloves and goggles.
Step 2: Low-risk cleaning method
You should remove the cartridge from the filter housing carefully, avoiding bumping or crushing.
Next, you should clean it with a clean cleaning fluid and rinse it at low pressure from the inside to the outside of the cartridge to allow the dirt to be washed out.
Do not use high-pressure water, hard brushes, sharp tools, or caustic cleaners during the cleaning process.
Step 3: Drying, inspection, and reinstallation checks
After cleaning, you should let the cartridge dry naturally or blow it dry with clean, low-pressure air.
Before installation, you should check if the cartridge is deformed, broken, or has dirt left on it.
You should also check the condition of the seals to see if they have deteriorated and deformed.
If you find any abnormality in the cartridge and seals, don’t continue the installation; you should just replace them.
If everything is in order, you can install the cartridge back into the filter and tighten it.
How Hydraulic Applications Affect Filter Cleaning Decisions
Different types of hydraulic systems have different needs when it comes to how clean the fluid is and how stable they are. If you decide to clean the filter, the way you do it and the risks you are prepared to take should be based on how you are going to use it.
Industrial Stationary Systems
Most industrial fixed systems are made up of hydraulic presses, bending machines or testing equipment. These devices usually work in fairly stable environments where there is not much contamination from outside. When cleaning, it is important to do it in a clean environment. After cleaning, check that the filtration performance hasn’t got much worse. This will help to stop the system from becoming less precise because of incomplete cleaning.
Mobile Hydraulic Equipment
Mobile hydraulic equipment is mainly made up of excavators, forklifts and agricultural machinery. This equipment works for a long time in places where there is a lot of dust and vibration. This means that the filter parts can get dirty with silt and sediment. When you clean it, make sure you get rid of all the deposits and stop any particles from getting back into the system. After cleaning, it is very important to closely monitor the system’s performance.
High-pressure or Precision Hydraulic Systems
High-pressure or precision hydraulic systems are mainly used in injection moulding machines, precision machine tools, or servo-controlled equipment. These systems need very clean fluid. When you clean it, make sure the place where it’s being cleaned is kept very clean. This will stop the filter from getting damaged. After reinstalling it, keep a close eye on how the system is working and changes in pressure. This will help to stop small problems from getting worse.
Auxiliary or Low-risk Circuits
Auxiliary circuits or low-risk circuits are made up of oil cooling circuits or low-pressure return oil circuits. These circuits don’t affect the main system’s functions. If you do clean it, make sure you meet the basic cleaning standards and avoid using the same cleaned filter element for a long time to reduce the risk of problems.
What Are the Risks of Cleaning a Hydraulic Filter?
Cleaning a hydraulic filter will not cause a problem straight away, but it will change the working condition of the filter while you are using it. These changes are not obvious at first, but will be gradually amplified in the long-term operation of the system, thus affecting the stability of the entire hydraulic system.
Reduced Filtration Accuracy
The filter structure of the cartridge may be worn during cleaning. Even if it does not appear to be damaged, the actual filtration accuracy may have deteriorated. This can lead to more contaminants entering the system, which can wear out valve parts and pumps more quickly.
Loss of Structural Integrity
Repeated cleaning can make the cartridge less sturdy than it should be. The cartridge is more likely to deform or break if there is a lot of pressure or high vibration. Once this happens, it is difficult for the filter to continue to protect the system.
Higher Risk of Secondary Contamination
When cleaning and reinstalling the cartridge, you will certainly open the protective cover. If the environment is not clean enough or the cartridge is not completely dry, new contaminants such as dust and moisture may enter the system.
System Reliability Impact
If there is less filtration and more secondary contamination, the system usually doesn’t fail straight away. But it can make some parts of the system wear out more quickly. In the long run, this can lead to the following problems: the machine may malfunction, you may have to do more maintenance, and you may have to stop the machine working when you don’t want to.
Common Hydraulic Filter Cleaning Mistakes to Avoid
In actual maintenance, many filter problems are not caused by cleaning itself, but by improper cleaning practices. The following things should be avoided to keep your filter in good condition and stop dirt from getting into the system.
Using High-pressure Water or Air
Cleaning with high-pressure water or high-pressure gas tends to wash out the filter structure of the cartridge. Even if the appearance of the problem can not be seen, the filtration effect has often deteriorated.
Using Abrasive or Sharp Cleaning Tools
Brushing the cartridge with a steel brush, hard brush, or sharp tool can easily scratch or prop apart the structure of the cartridge. This type of damage is usually permanent and will affect the filter’s ability to filter water.
Cleaning Disposable or Non-reusable Filters
Disposable cartridges are meant to be replaced and are not suitable for cleaning. Forced cleaning is ineffective and may also dislodge the filter media and contaminate the entire system.
Using Unapproved or Harsh Cleaning Chemicals
If you use a cleaner from an unknown source or one that is very corrosive, you may injure the cartridge or seals. You might not notice the problem at first, but the system will probably fail after some time.
Improper Drying or Inspection Before Reinstallation
If you put the cartridge back in without drying it or checking it first, you can easily bring moisture and other impurities into the system, which can cause secondary contamination.
Cleaning vs Replacement: Which Is Better for Hydraulic Filter Maintenance?
When Should Cleaning be Considered?
If the system uses reusable filter cartridges, operates on auxiliary or non-critical circuits, experiences only mild contamination, and cleaning is solely for temporary restoration of equipment operation, then cleaning may be considered, provided risks are manageable. In these cases, the system’s filtration precision requirements are not very strict, and short-term cleaning usually does not have a big impact on equipment, as long as filtration performance stays reliable after cleaning and no new contamination is introduced.
When Should Direct Replacement be Performed?
Replacing the filter element is generally a better idea if the system uses disposable parts, operates under high pressure, or is part of a precision control circuit. It is also a good idea to replace the filter element if the equipment needs to operate reliably over a long period of time, or if the filter element is severely clogged, deformed, or damaged. If you can’t be sure that the filter is working as well as it should after cleaning, you should replace it. For most industrial uses, replacing the filter part makes it more stable and easier to control.
FAQ
How often is it better to clean the washable cartridge?
There is no fixed time for cleaning the cartridge. This depends on how contaminated the system is and the operating conditions. You should only clean the cartridge when it is a little dirty, and the equipment is still working well. Don’t clean it often.
Will cleaning the cartridge affect the warranty of the equipment or system?
It might have an effect on it. Many equipment or cartridge manufacturers only recognise maintenance by replacing the cartridge. If the manufacturer doesn’t clearly say you can clean the cartridge, they might not honour the warranty if there’s a problem.
After cleaning, how can I tell if the filtering performance of the cartridge is still up to standard?
After cleaning the cartridge, there is no way to accurately detect the filtration effect like a new cartridge. You can only judge indirectly by observing the appearance, the change of differential pressure, and the operation status of the system, but none of these can completely determine whether the filtration performance has been restored to the original level.
How many times can I wash the same cartridge?
There isn’t a normal way to work out how many times you can clean a cartridge. Every time you wash the cartridge, the filtering effect of the cartridge will decrease a little. If you find that the cartridge is deformed or damaged, or the performance is no longer good enough to judge, don’t clean it again; just replace it.
What are the clear signals that the cartridge is no longer suitable for cleaning?
If the cartridge appears to be seriously clogged, shows structural deformation, broken filter material, unremovable pollutants, or abnormal operation of the equipment after cleaning, it means that the cartridge is not suitable for cleaning anymore, and should be replaced with a new one directly.
Is there a common standard or specification for cartridge cleaning in the industry?
At present, there is no set of uniform cleaning standards in the industry applicable to all hydraulic cartridges. When it comes to actual maintenance, it is best to follow the recommendations given by the cartridge or equipment manufacturer, instead of deciding how to clean it at your own discretion.
Final Thoughts
Not many people clean their hydraulic filters. You should decide if cleaning is right for you based on the type of filter, how important the system is, and the risk of using it. For most industrial equipment, it’s better and easier to just replace the filter elements directly.
Target Hydraulics has over 10 years of experience in hydraulic filtration and system applications. We can help you choose the right cartridge, give you advice on replacing it, and provide technical support. This will help you to reduce the risk of maintenance problems and make your equipment last longer. If you’re not sure whether to clean or replace it, contact us for advice.
