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How can you protect your hydraulic systems?
How can you protect your hydraulic systems?
Tips and advice

How can you protect your hydraulic systems?

03.09.2024

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Contamination of hydraulic fluid

Hydraulic systems are essential in many sectors, where their reliability and efficiency play a crucial role. However, the performance of these systems can be seriously compromised by various contaminants in the hydraulic fluid. Contaminants such as solid particles, water and gases can cause costly breakdowns and significantly reduce component life. Understanding the sources and effects of these contaminants is essential to implementing effective preventive measures and keeping hydraulic systems running smoothly.

Solid particles

Particles are responsible for 80% of hydraulic failures. Their size, shape and hardness determine the extent of potential damage. In particular, they can cause premature wear on the functional surfaces of components, shorten the life of systems, and lead to blockages or a reduction in the precision of components. There are many reasons for this:
  • Integrated contamination: Residues from the manufacture of machinery or from new oil that has already been contaminated.
  • Contamination generated: Normal and abnormal wear and tear on systems during operation.
  • External contamination: Introduction of particles during fluid transfer, maintenance, or via cylinder rods and air intake vents.
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“💡 Standards for assessing particulate pollution include ISO 4406 (European), NAS 1638 (industrial), SAE and NAV AIR (marine hydraulic fluids). They set thresholds for measuring contamination by solid particles.“

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Water

Water is a frequent contaminant in hydraulic systems, responsible for one in five breakdowns. Once in the system, it causes oxidation of the fluid and attacks its additives. It also corrodes metal parts and reduces the fluid's lubricating capacity.
This contamination is generally due to condensation. When moist air enters through the intake vents, the large temperature variations and thermal shock caused by the return of the hot fluid into the reservoir transform this gas into a liquid, which then settles in the reservoir and contaminates it. Damaged vents, leaking seals or heat exchangers can also allow water to seep in.

How do you know if the oil is contaminated by water?

The water in the hydraulic fluid can take different forms.
  • In dissolved form, it is imperceptible, but can still affect the properties of the fluid.
  • Free water, on the other hand, accumulates in visible droplets at the bottom of the tank or components.
  • Emulsified water gives the fluid a milky appearance, increasing its viscosity and causing lubrication problems. To detect water contamination, test your fluid regularly.

Gas

One of the main causes of gas contamination is cavitation. This phenomenon occurs when the pump creates a vacuum by sucking in the fluid, causing air bubbles to form. Other factors such as leaks, poor circuit design, insufficient oil level or nitrogen leaks can also introduce gas into the system.
 
The presence of gas in hydraulic fluid can cause a number of problems, such as premature wear of components due to erosion caused by cavitation, foaming affecting lubrication, increased oxidation accelerating fluid degradation, elasticity reducing the responsiveness of components, and the generation of heat under high pressure which can damage seals and other sensitive parts of the system.
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The HIFI FILTER® range of filters for hydraulic fluids

Filters are crucial elements in hydraulic systems, blocking impurities, protecting components and extending the life of the system. The level of filtration depends on several factors:
  • Cleanliness requirements and component sensitivity
  • The level of contamination in the ambient environment
  • The machine's operating cycle
  • Easy maintenance of components and spare parts
  • System operating pressure

HIFI FILTER® offers a wide range of housings, filters and accessories, designed for different pressure levels and locations in the hydraulic circuit, from fluid intake to pressure zone, tank venting and return.

Aspiration

Suction filters are located in the tank (suction strainer) or before the pump (suction line filter). Their main function is to protect the pump.
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Pressure

Filters purify the fluid after the pump, protecting the directional control valve, servo valves, cylinders and other sensitive and expensive components. Whatever the operating pressure of your system, the HIFI FILTER® range includes filters for low, medium and high pressure lines.
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Return to

Located after the receiving components, these filters decontaminate the fluid before it is returned to the reservoir. There are two types: return line hydraulic filters, installed in series on the return line to eliminate contaminants, and tank return filters, installed at the tank inlet to ensure that only clean fluid enters the tank.
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Tank ventilation filters and air dryers

During the operation of a hydraulic system, ambient air is introduced into the reservoir to compensate for variations in oil volume.
  • Aeration filters: Installed on tanks, aeration filters contain a filter medium (foam, cellulose or fibre) to capture solid particles before they contaminate the tank and damage the system. Some of these filters are fitted to the tank vent, while others are integrated into the cap.
  • Air dryers: These combine particle filtration with the retention of moisture contained in the ambient air. Inside, silica gel beads, a desiccant material, capture moisture and a filter medium retains solid particles.

💡 When the silica gel beads change colour, this indicates that the filter is saturated with moisture and needs to be replaced.
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Tank accessories

You'll also find a whole range of accessories in our catalogue, including :
  • Diffusers: Installed in the tank, they prevent the formation of foam and limit the spread of contaminants in the tank, preventing them from entering the circuit.
  • Filler caps: Used as pre-filtration devices, they retain external contaminants during refuelling thanks to a filter screen.
  • Level indicators: These monitor the fluid level and alert the user. 💡 A level that is too low indicates normal or abnormal oil consumption. Conversely, if the level is too high this may be due to water ingress in particular.
  • Clogging indicators: These measure differential pressure to indicate when a filter is clogged and needs replacing.
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Filter groups

This range includes mobile transfer units and off-line fixed purification units. Both types of unit are designed to purify hydraulic fluid. Depending on the model, they remove water and/or particles, keeping the system clean and efficient.
To find out more about these maintenance solutions, read our dedicated article here.
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Maintenance tips

Regular maintenance is essential to keep hydraulic systems running smoothly. Here are some key tips to follow:
  • Follow the manufacturer's recommendations: Consult the maintenance manual to find out what type of fluid to use and how often to change it.
  • Do not mix fluids: Always use the same type of hydraulic fluid to avoid undesirable chemical reactions that could damage the system.
  • Check the fluid level: Make sure the level remains sufficient to avoid pressure problems, cavitation and premature wear.
  • Analyse the fluid regularly: Test for the presence of water, solid particles or other contaminants. This helps identify potential problems before they damage the system.
  • Check filters: Replace filters if they are contaminated or damaged. Clogged filters can cause breakdowns.
  • Plan regular maintenance: Include fluid replacement, tank cleaning and mechanical component checks in your maintenance programme. This will reduce the risk of failure and extend the life of the system.