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An air chamber is a space filled with air, commonly to act as a cushion or shock absorber for a closed system. The chamber may be designed directly into the system or added at a later date to address a problem. A common example of a system including an air chamber is a hydraulic system like that used for hydraulic doors and in braking systems. In both cases, air chambers play an important role, although free-floating air in the system is not desirable.
A common use for an air chamber is to create a buffer in a closed system where fluids or gases are moving inside the system and the pressure changes as a result. If an air chamber was not present, the system could be noisy or might be at risk of rupture from the pressure. In a simple example, household plumbing can develop a phenomenon known as “water hammer” when pressure changes abruptly, as when people turn taps on and off. This creates a loud knocking sound that many people find unpleasant. An air chamber will allow for expansion and compression within the system without loud noises, making the plumbing quieter.
In a hydraulic system, air chambers allow for changes in pressure so the system can function. Too much pressure can create unreasonable resistance, making it hard for humans to use the system, as anyone who has driven in a car with very stiff hydraulic brakes can attest. Not enough pressure will make the system less functional; a hydraulic door, for instance, might not stay shut if there wasn't pressure inside the system to keep it closed. The air chamber creates room for pressure fluctuations.
Air chambers may have an emergency valve to vent air if pressure rises too high, allowing the system to bleed off pressure before it explodes. This can be an important safety feature, as systems with no pressure outlet may become dangerous, even under normal operating conditions. Air can be admitted back into the air chamber as needed through the same valve. The chamber also provides a method for bleeding air out of the system, allowing it to rise into the chamber where it can be released.
If an air chamber needs to be replaced or installed, the system will need to be shut off to allow people to work on it. Fittings must be carefully installed to make sure the system is still sealed. Once this is done, the system will be allowed to refill, and then it will be turned back on, and tested. If problems develop, they are addressed at the time of installation.