Filler breathers

What is the function of filling and ventilation filters?

Filling and ventilation filters are needed to fill and ventilate hydraulic tanks. These filters ensure that the tank is permanently ventilated. Depending on the design, these filters have integrated slosh protection. They also protect against dirt and impurities that enter the tank opening during machine operation. As an option to support and ensure this protective function, ELSÄSSER also recommends installing an air filter element.

Vent filters are therefore essential for efficient air exchange, especially in hydraulic systems. They ensure that the air is sucked in, the dirt particles are kept out and the pressure fluctuations in the tank are thus equalized. The drying granulate absorbs the moisture from the ambient air, which prevents condensation from forming in the tank. The non-return valve ensures that the amount of dirt particles entering the tank is minimized. The suction process of the pump is supported by a tank preload, which is made possible by the application of pressure. These processes are particularly important because the oil level in a hydraulic tank can vary due to temperature fluctuations, operating conditions or the movement of working cylinders.

How are breather filters used?

The main function of breather filters is to protect hydraulic systems from contamination by outside air while ensuring the necessary air exchange for pressure compensation in the hydraulic tank. This results in the following applications, among others:

In general, this means that vacuum in the tank can be avoided, overpressure can be reduced and the hydraulic fluid is protected from quality losses. It is important to note that reduced ventilation cycles ensure a longer service life for the ventilator, shorter maintenance intervals and a longer fluid service life. Foaming and cavitation in the container are also reduced as a result.

Furthermore, breather filters are used in stationary and mobile hydraulics, for example, especially directly on the hydraulic unit. Ideally, the filters are placed directly on the hydraulic tank. The filtration grade of the breather filter should be finer than that of the finest filter in the hydraulic circuit.

What advantages do breather filters offer?

• Reduced air exchange: The double check valve minimizes the ingress of dirt.
• Sloshing protection: Prevents oil from leaking out of the tank.
• Easy oil level check: Integrated dipsticks make monitoring easier.
• Easy maintenance: An integrated clogging indicator signals the optimal time for filter maintenance.
• Cost savings: Maintenance is simplified by integration into tank-mounted return-line filters.

What types of contamination can occur in hydraulic systems?

• Solid particles: Dust, sand and metal abrasion.
• Liquids: Water can cause corrosion and degrade the hydraulic fluid.
• Chemical contamination: oxidation or decomposition of the hydraulic fluid impairs system performance.

These contaminants cause increased wear on pumps and valves, efficiency losses and potential system failures. Regular maintenance and effective filtration are therefore essential.

Notes on combining with other systems

When filling the reservoir, the new mineral oil should be filtered, as it often contains higher levels of contamination. Filler breathers consist of an air filter for the incoming air and a filler screen that retains coarse dirt during filling.

It makes sense to combine the filling filter with a flushing unit to speed up the filling process with cold oil.