Lifting bag

A lift bag used to lift objects under water and the transport to the surface. In this case, this is filled with normal air and rises due to the lower density of the air to the water surface when the buoyant force exceeds the attached weight. Depending on the size and design of a separate air tank is used, which is carried exclusively for this purpose or the lift bag is filled using the octopus. The second method is used primarily for smaller lift bags in the range up to about 100 liters of buoyancy volume application.

The extent of under ambient pressure air in the lift bag during ascent caused by the declining ambient pressure a further boost increase until the maximum fill the lift bag is reached. The increased further by decreasing ambient pressure during further climbing volume of the inflation air escapes through the open bottom design freely into the water. A burst the lift bag is excluded. It is therefore appropriate to choose the lift bag of its dimensioning forth so that the load is increased until reaching the maximum filling. The buoyancy increase in expansion is otherwise a risk that the lift bag significantly gaining buoyancy, and uncontrollable by shoots up to the surface, rather than slow and controlled to rise. This may also have the consequence that the lift bag to the surface loses considerably in air and then together with the suspended load at high speed drops again and this is a danger to (eg, the present underneath divers). To prevent uncontrolled rises many lifting bags have a simple valve may be vented during the ascent to the excess air.

There are lift bags in various sizes in use, for example, a lift bag with a volume of 100 l lift an object weighing of 100 kg under water. Lift bags are primarily used by fire departments, the THW and water rescue organizations, but also from individuals.

In the field of technical diving find lift bags, there often referred to by the English term Liftbag, use as a replacement for the signal buoys otherwise often used. Since Liftbags have better stability at the surface and a higher load capacity, these are set when the Technical diving some of them already in great depth in order to use the leash, which is thereby unwound from a coil as a climbing reference and tether for decompression stops.