GN 774 Breather Caps Plastic, with Filter, with Double Valve

Breather caps GN 774 with double valve are normally used if the oil container is under pressure and if outside air has to flow back in to compensate for the vacuum caused by falling oil level.

This is achieved by combining two valves (non-return / bypass valve). The inlet valve opens at a vacuum of 30 mbar or greater. The second valves opens at an overpressure > 350 / 700 mbar.

The air filter prevents the oil from being polluted from the outside (dust). The filter is made of PU foam with a filtration of 40 µm.

The overpressure inside the container ensures that the air volume flowing in or escaping owing to fluctuations of the oil level is kept to a minimum. This reduces filter fouling and substantially increases the useful filter life, especially in a dusty environment.

Also, a container under pressure has a positive effect on the function of the pump and prevents foaming.

The valve seal ensures that no oil can spill to the outside, neither by excessive agitation in the tank nor during transport.

Level markings and special lengths GN 109 for oil dipsticks are available for the standards shown above. The dipstick is shortened to the length l₁ and the marking notches are milled in at l₂ or l₃ with the effect that they are easily visible. The maximum length l₁ is given in the appropriate standard. 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 and depending on standard, the seal must be taken into consideration with a thickness of as much as 2 mm.
If required, more than 2 notches may be cut which are then specified by the appropriate details on the position
(l₄ ... l_x). Also, texts such as MAX / MIN may be laser-engraved in addition to or instead of the notches by submitting the
appropriate template.

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