An air breather is installed on a fluid reservoir to:

An air breather is a crucial component installed on a fluid reservoir primarily to vent the reservoir. It allows air to enter and exit the reservoir as the fluid levels change during operation, which helps to maintain atmospheric pressure inside the tank. This function is essential because without proper ventilation, a vacuum can form as fluid is drawn out, potentially leading to operational issues such as cavitation or deformation of the reservoir.

By allowing air to flow in and out, an air breather also helps prevent the formation of excessive pressure within the tank, which could lead to leaks or ruptures. Additionally, while air breathers can help minimize the entry of larger contaminants, their primary purpose is venting to maintain fluid dynamics and reservoir integrity. This does not correlate directly to increasing fluid pressure, improving fluid viscosity, or solely protecting against contaminants, which are functionalities associated with other components or systems in hydraulic mechanisms.