These machines are used for packaging items that need to have all of the oxygen or air removed from the interior space of the package prior to sealing. These are often times called double chamber machines because the vacuum chamber lid is mounted above the two sealing chambers on a set of see saw type pivot brackets.
To operate this machine the bagged or pouched products are loaded into the sealing chamber with their open tops lying along the edge of a heat seal bar. The chamber lid is the swung down over the loaded sealing chamber. A set of sealing bars that match the position of the ones below in the sealing chamber are mounted in the chamber lid. When the lid is closed the open edge of the bag of package is sandwiched between heat sealing bars above and below. The operator hits the start button and a huge vacuum pump turns on to suck all the air out of the sealing chamber. Once the desired amount of vacuum has been reached an electric pulse is fired to energize the heat seal bands and melt the ends of the bag or pouch together to create a seal. After a few seconds of cooling off an equalizer valve is opened and the pressure inside the chamber equalizes and the lid can be opened up.
While the one chamber was evacuating and sealing the operators are supposed to be loading the adjacent seal chamber up with packages ready to be sealed so as soon as the pressure equalizes on the chamber that made the seal the lid can be swung over onto the next chamber to start the cycle again while the first chamber is loaded so as to achieve a continuous production.
Only a handful of manufacturers make these machines. Most of them are made well because they are simple in nature. At my company we operate them at such a high frequency I have installed oversized electric components which can remain cool and last longer throughout prolonged operation. We have installed larger sized motor starters for the vacuum pumps, and very high current solid state relays for the heat seal bands to reduce the downtime on these machines. Other than that they work OK.
The ones we have all use vacuum pumps made the Busch Company, which I have to say are very high quality and long lasting pumps. It is better to pay a little more for a piece of equipment that you know will run and run rather than save a few dollars and buy something that just won't last. Busch pumps are worth the extra cost and I am not getting paid to say this.