A vacuum sealer is a device that typically both removes the air from, and seals, a special type of plastic bag. These products are most often used for preserving food, but they can be useful for other purposes as well. Basic private-use sealers have a suction motor and a heat sealer onboard, while some of the commercial-grade versions may use a outboard air compressor.
For the most part, a vacuum sealer is used with food items. Perishable food that has been vacuum sealed may retain its freshness for a longer period of time than if it is left open to the air. These products may also help items resist freezer burn as well.
A standard vacuum sealer typically has three options for sealing food. First, items may be placed inside a preformed plastic bag and the open end of the bag would be placed in the machine. The sealer should then vacuum out the air from the bag.
After the air is removed, the vacuum sealer usually seals the bag. This is generally accomplished with heat, so that the plastic melts and creates a solid closure. The bag can then only be opened by cutting it below the heat seal.
Second, many sealers allow users to create custom-sized bags from a roll of special plastic. The user typically measures out the plastic and cuts it to the desired length. Then he or she will usually heat seal one end of the plastic, put items inside the newly formed bag, and place the other, open end into the vacuum sealer. The device then vacuums out the air and heat seals the bag.
Third, some of these appliances have attachments that allow them to vacuum special canisters as well. Typically, a hose runs from the vacuum sealer to an attachment on the lid of the canister, where it removes the air. The canisters are usually closed until the lid is unscrewed, breaking the seal.
Some sealers offer several speeds of suction, allowing users to customize the amount of pressure placed on the food. Devices that have adjustable suction may offer special settings for different types of food items. This feature may allow users to stop a suction process early to avoid crushing soft foods.
There are other types of vacuum sealers than the standard private-use models. Some devices are simply handheld vacuums that attach to specially-designed bags, and often do not require heat sealing. Industrial sealers are typically large-scale, automated machines. Commercial sealers usually work in a similar manner to private ones, but they generally handle a larger capacity.