EN 774 Breather Valve Caps Plastic, with or without Dipstick, with Double Valve

Breather caps EN 774 feature a double valve and are used for venting vessels, such as hydraulic tanks. The valve limits the overpressure inside the vessel by releasing air whenever the pressure value specified in the table is exceeded. Conversely, the valve allows air to enter into the vessel once an underpressure of -30 mbar is reached, preventing the formation of a vacuum. The respective flow rate depends on the pressure difference and can be read from the diagram.

The integrated air filter prevents dust and dirt from entering the vessel. With fluctuating liquid levels, the overpressure reduces the air exchange, resulting in reduced filter contamination, especially in dusty environments.

The pressurized air pocket above the liquid counteracts foam formation. The valve seal ensures that no liquid escapes, such as due to vigorous movements or during transport.

For the series with dipstick shown above, a shortening and / or the attachment of level markings can be ordered with the service GN 109.
The dipstick is shortened to the length l₁ and the marking notches are milled at l₂ or l₃, making them easily visible. The max. length l₁ is specified in the respective series. The length specifications l₁ to l₃ refer to the contact surface without seal, with a tolerance of ±1 mm to be taken into account. For critical applications, the seal must be taken into consideration with a thickness of up to 2 mm, depending on the series.
If required, more than 2 notches may be inserted on request, which are then specified by appropriate details on the position (l₄ ... l_x). Furthermore, texts such as MAX / MIN may be laser-engraved in addition to or instead of the notches by submitting the appropriate template.

The fluid level markings / special lengths GN 109 are to be ordered as a separate item in shopping cart step 1 under note.