Tips to Reduce Hydraulic Fluid Contamination.

19/02/2020 9:13:50 AM


All hydraulic systems feature high precision components, which are vulnerable to very small amounts of contamination. Even microscopic metallic particles that make their way between close-fitting reciprocating surfaces can very quickly bring even the most powerful hydraulic systems to their knees.

Thus, hydraulic fluid contamination is a big concern for maintenance managers, which is why you should be looking for anything that will minimise the presence of impurities and particulates in your hydraulic fluid. With that in mind, here are some simple things you can do to reduce the levels of contamination within your hydraulic system.

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Tips to Reduce Hydraulic Fluid Contamination.

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Take regular fluid samples and keep a log of hydraulic fluid condition.

One way to reduce contamination is to be aware of the contamination levels within your system at all times. Doing so will alert you to a problem when anything out-of-the-ordinary occurs. If contamination levels rise suddenly, it’s an indication that there may be a problem somewhere in the system. For example, a component may be wearing out or a seal may be failing - causing an increase in foreign matter in the fluid.

So, it’s a good idea to sample your fluid and keep a daily, weekly or monthly log to keep an eye on contamination levels and gain an understanding of the fluid contamination patterns in your system.


Change hydraulic fluid according to the prescribed schedule.

Routine maintenance is by far the best way to ensure your hydraulic fluid stays clean and contamination-free. Hydraulic fluid is a wear item and requires regular replacement. This involves completely draining and flushing the hydraulic system and replacing the old, oxidised oil with fresh clean oil. Doing this on a regular basis, before contamination levels rise, will reduce the amount of debris buildup within the system and ensure the chemical composition of the oil is maintained and contamination levels stay lower over the long term.


Follow the correct procedure when draining hydraulic fluid.

Make sure you drain 100% of the old fluid and remove all of the impurities that may be present. To do so, make sure you start the system and bring it up to operating temperature before you drain the fluid. Doing this gets the fluid moving and causes settled deposits to free up and become suspended in the fluid - which ensures all those impurities leave the system when you drain the fluid. If you suspect the system may have accumulated deposits of oil or debris present, you may use a light viscosity oil to flush the system.


Filter new hydraulic fluid before replenishing the system.

Even new hydraulic fluid is sometimes not 100% free of contaminants. To make doubly sure of the cleanliness of your fluid, you may consider filtering the replacement hydraulic fluid through a very fine - 10 micron filter.


Use the correct hydraulic fluid for the application.

Different fluids offer different wear protection and chemical stability properties that make them more, or less suitable for different applications. There are several factors that may influence the choice of hydraulic fluid required - these include operating temperature, stroke speed, duty cycle and the chemical composition of the fluid. For example, hydrostatic transmissions and control mechanisms may require a different viscosity fluid than is required by hydrodynamic systems. Using the wrong specification fluid may lead to premature fluid breakdown and accelerated wear. Check the hydraulic fluid recommendations with your equipment manufacturer.


Change hydraulic fluid according to operating conditions.

Changing temperature conditions and environmental factors may necessitate a different choice of hydraulic fluid. For example, colder climates can see drastically lower temperatures in winter, which makes it necessary to utilise lower viscosity oil during the colder seasons. However, should conditions change and you continue to use the machine, it could lead to a situation in which the fluid becomes too hot, loses viscosity and breaks down, which may lead to accelerated wear and increased contamination. Check your equipment manufacturer’s maintenance manuals for guidance on the correct fluid to use in different operating conditions.


Replace hydraulic filters regularly.

Hydraulic filters are your best defence against contamination, but when they become clogged they lose the ability to effectively remove impurities from the fluid. So, it’s important to keep an eye on the health of your filters and change them according to the prescribed maintenance schedule. You can either keep an accurate log detailing which filters have been changed and when they’re due for replacement, or alternatively there are purpose-designed clogged filter indicators available that provide a visual signal that lets you know when it’s time to change.



A clean hydraulic system is a healthy hydraulic system. Hydraulic fluid is the lifeblood of your machine and just like you work better without impurities running through your veins, your hydraulic fluid needs to be kept clean and free of contaminants. These tips will help you to reduce contamination levels and keep your hydraulic fluid healthy.


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