Breather Filters for Clean Hydraulic Oil

The breather filter is a central component in large hydraulic systems. It is used wherever significant fluctuations in oil volume are expected in the reservoir.

Breather filters are essential for the operation of hydraulic systems. They protect the system from contamination and thus contribute to operational readiness.

Breather Filters, Because a Hydraulic System Breathes

During operation, a hydraulic system experiences numerous fluctuations in the oil tank. The oil is pumped into various applications as needed and then flows back into the tank.

These fluctuations must be pneumatically compensated; otherwise, there is a risk of damage to the hydraulic tank, potentially leading to the failure of the entire system.

When hydraulic oil is pumped into the system, the same volume of ambient air must flow back into the tank. Otherwise, a dangerous vacuum will form, which can lead to the implosion of the tank.

Avoid Unwanted Contaminants Thanks to Breather Filters

Unfortunately, ambient air is not particularly clean; quite the opposite. Working machinery with large hydraulic systems, such as excavators, handling equipment, cranes, or telehandlers, already generate a high concentration of fine particles in the immediate vicinity of their hydraulic tanks due to their diesel engines.

Similarly, the ambient air around working machinery is already heavily laden with suspended particles due to the nature of the work itself. Excavators stir up dust, handling equipment generates many particles when loading bulk materials, and large agricultural machines are exposed to significant amounts of dust.

To prevent these microparticles from entering the hydraulic fluid, the ambient air must be filtered. This is where breather filters come into play.

More Than Just a Particle Barrier

However, the breather filter must also cope with another challenge. Ambient air is always enriched with water vapor. Water should under no circumstances enter the hydraulic tank, as it has a doubly damaging effect on hydraulic oil.

• Water causes oil to age prematurely and promotes the growth of fungi and other microbes that degrade and transform the hydraulic oil.
• Water evaporates quickly under heat and pressure. This creates compressible gas bubbles in the hydraulic system. Water vapor can thus bring hydraulic applications to a standstill.

Depending on the breather filter, they may also have a water-separating function.

Position and Design of a Breather Filter

There are two types of breather filters.

Modules with an integrated air-drying unit sit on top of the tank. The incoming air is passed through a desiccant, which removes moisture from the air, preventing it from entering the hydraulic oil.

The second design extends into the tank. This solution is ideal for environments with limited space. This principle is therefore often found in construction machinery.

In particularly high-quality machines, the air entering the hydraulic tank is pre-cleaned and dried.

Both systems are designed for easy replacement and cleaning. Breather filters are generally very durable and reliable.

For compact systems, so-called multifunction filters have proven effective. These not only offer reliable filtration of incoming air but also fulfill a variety of additional tasks:

• Level monitoring
• Temperature control
• Pressure control in the hydraulic system
• Sensor-based remote monitoring

While these multifunction devices are somewhat more expensive, they can eliminate the need for many additional modules in the overall system.