A typical airplane has hundreds of thousands or even millions of parts. While most people are familiar with major parts like the wings, tail and engines, smaller parts like breather vents often go unnoticed. Nonetheless, breather vents play an important role in protecting airplanes from pressure buildup, contamination and even mechanical stress.
The Basics of Breather Vents
Breather vents are ventilation passages that allow air to escape from a container or closed system. Also known as breather tubes, they are often used for pressure equalization. By allowing air to escape, breather vents prevent excess pressure from building up in containers and systems. Some breather vents also have screens or filters to remove dust and debris.
Why Airplanes Use Breather Vents
Modern airplanes feature many closed systems, such as oil and hydraulic systems. They are sealed to prevent their respective fluid from leaking out, and to prevent the intrusion of environmental contaminants. Pressure changes, however, can affect these systems.
Atmospheric pressure is heavily influenced by the altitude at which an airplane flies. When an airplane ascends to a higher altitude, it will be exposed to a lower atmospheric pressure. This is because the air is less dense at high altitudes, as the air molecules are spread farther apart.
When it descends to a lower altitude, the airplane will be exposed to a lower atmospheric pressure. Descending from 35,000 feet to sea level, for instance, will result in roughly a 75% pressure drop. These pressure changes can affect any air trapped inside closed systems.
How Pressure Changes Affect Closed Systems
When the atmospheric pressure changes, the pressure of trapped air inside closed systems will change with it. Assuming the system is fully sealed — meaning there’s no way for air to escape — this can lead to pressure buildup or negative pressure (vacuum).
During ascent, the air will expand, resulting in pressure buildup. During descent, the opposite occurs: the air will contract, resulting in negative pressure. Both scenarios can cause serious problems, such as leaks, blowouts and failed components. Breather vents offer a solution by allowing closed systems to breathe.
Breather vents work by allowing air to move in and out of containers and closed systems. They don’t stop changes in atmospheric pressure. Rather, they equalize the pressure of containers and closed systems with that of the surrounding atmospheric pressure. By doing so, problems associated with pressure buildup and negative pressure are less likely to occur.