Modern airplanes rely on pressurized air or gas for many purposes. Deicing boots, for instance, are designed to dislodge and remove ice from an airplane’s wings when inflated. Commercial airliners use pressurized air, known as bleed air, to regulate the cabin climate. Pneumatic systems such as these, however, often require specialized valve caps.
What Are Pneumatic Valve Caps?
Pneumatic valve caps are components that seal the end of a valve in a pneumatic system. They are designed to protect the pneumatic system from dirt, dust, moisture and other contaminants. At the same time, pneumatic valve caps help contain the pressurized air or gas so that it doesn’t escape the system through the valve end.
All pneumatic systems are pressurized. There are low-pressure pneumatic systems that operate between 1 and 10 PSI. There are also medium-pressure pneumatic systems that operate between 50 and 150 PSI. There are even high-pressure pneumatic systems that operate between 1,000 and 3,000 PSI.
Valve Cores vs Valve Caps
Valve caps and valve cores aren’t the same. While they are often used together, they have different purposes. A valve core is a component inside a valve that controls the passage or air or gas. It can allow air or gas to enter the valve, and thus the pneumatic system, or it can prevent air or gas from entering the valve.
A valve cap is simply a sealing component that fits over the top of the valve. It’s not a replacement for a valve core; pneumatic system valves still require a core to control the passage of air or gas. The cap simply seals the outside of the valve.
How Pneumatic Valve Caps Work
The mechanics of pneumatic valve caps are simple. They feature internal threads that connect to the external threads on the outside of a valve. To install them, you simply need to place the cap over the valve and turn it clockwise. Alternatively, you can loosen and remove a valve cap by turning it counterclockwise.
Turning a valve cap clockwise over a valve will tighten it. Eventually, the valve cap will reach the installed position, at which point the sealing element will make contact with the valve’s sealing surface. Once in this position, the valve cap will seal the valve to prevent leaks.
Many pneumatic valve caps also provide a secondary seal. Even if the main seal fails and begins to leak, this secondary seal serves as a backup to prevent pressurized air or gas from escaping.
