I am building a desoldering gun. While the pump I am using provides decent suction, I would like a quick powerful vacuum burst to prevent the solder from solidifying in the nozzle rather than in the chamber.
I figure there must be the equivalent of a capacitor where a vacuum is held in reserve and released when needed. Does such a device exist? If so what is it called. Finally, are they available in small sizes, say the size of a tennis ball?
The device is called a "receiver" in pneumatics - this is basically the tank you see on any garage compressor, or much larger and more elaborate setups in industrial settings. Its function can be modelled almost exactly like a capacitor. It stores energy by accumulating air inside of it (the integral of the incoming flow, just as charge is the integral of current), and will maintain a pressure (analogous to voltage) in proportion to its volumetric capacity after the external pressure source is removed. It even acts as a low-pass filter, essentially smoothing out the inconsistent input from the compressor, in fact this is the reason why garage compressors almost always have a tank attached.
In a lot of cases in the industrial world, receivers are seen at the point of usage as well, for example a valve that must close quickly, a pneumatic conveying line, or an air cannon. In those cases it's analogous to a capacitor used to store energy for a very high current but short discharge, such as a camera flash.
The equivalent of a capacitor in terms of pneumatics would be a chamber such as a metal sphere the size of a tennis ball. It would be necessary to have an external vacuum pump to evacuate the air prior to the quick release.
Auto tire houses use the reverse concept to seat a new tire on the rim. A cylindrical tank is loaded to substantial pressure by a compressor. The nozzle of the tank is shaped to fit the edge of the wheel rim and actuated by a ball valve, releasing a huge volume of air into the tire, assisting the seating process.
For your concept, you'd want to have a similar ability of opening the vacuum chamber, which may be more difficult than creating or finding a suitable chamber. For the application you describe, you can get away with a cylinder of some wall thickness but some experimentation may be required to determine the overall volume.
I'd expect that you'd have a permanently (in-use) attached vacuum pump at one end, the nozzle to apply to the solder to be removed at the other end and the release mechanism in the middle. After each use, the pump would have to remove the air, creating a bit of delay.
You may discover that a similar product using a vacuum pump exists:
It may have a chamber, or a pump with sufficient volume to accomplish the task.
