Emergency ascent
The emergency ascent is a value resulting from an emergency situation out, faster and more direct ascent to the surface. It may be the recommended ascent rate and decompression stops are disregarded. An emergency ascent from great depths is always the last chance to save their own and / or the life of Buddies. For divers, scuba divers or entire submarines and their crew there Notaufstiegs process. It can be distinguished between five different methods, which are considered in the following subsections.
Emergency swimming ascent
From a water depth of less than 12 meters a diver can relatively safely reach by direct Empor swimming, without lead - shedding and without inflating the BCD, to the water surface. In this ascent, the diver must exhale continuously throughout the climb up to the water surface. The air is in the lungs of the diver expands when a rise from 12 yards out in accordance with the law of Boyle -Mariotte by a factor of 2.2. Even after complete exhalation before the start of Notaufstiegs, the residual air may extend as far in the lung due to the decrease in ambient pressure that can cause a lung tear during the last meters before the water surface. This type of Notaufstiegs is often CESA (English: "Controlled Emergency Swimming Ascent ", German: "controlled emergency swimming ascent " ) called. In the Open Water Diver course, the PADI diving organization of CESA is practiced and tested.
Controlled emergency swimming ascent
By carefully inflating the BCD can a skilled divers are on a rise velocity of less than 10 m / min. The climb takes place without strokes with the flippers and keep constant the rate of ascent, every 2 to 3 m air must be vented from the BCD. With fading ambient pressure, the air expands and generates more lift. Also with this type of Notaufstiegs it is important that the diver can exhale constant during the whole ascent or at least a flat and strong exhales. Due to declining ambient pressure ranges from a rise of 60cm to cause a lung tear. At a depth of 3m must be stopped and, if the emergency permits, a decompression are performed by 3min. After a slow and secure appearance is possible. For deep dives is recommended to ascend as quickly as possible to 10 to 15 m to stop there and clean to tare. The rise can then max. 10 m / min to be continued up to 3m. The further rise after a decompression of 3min and slow emergence is usually considered safe. Nevertheless, this procedure can lead to varying degrees of decompression sickness. This can make a stay in a decompression chamber is required. In contrast to the rapid ascent but can be derived from the controlled emergency ascent often prevent permanent damage. Nevertheless, a medical check after each controlled emergency ascent is strongly recommended because symptoms can also only occur up to 48 hours later.
A diver whose buddy panics, injured, or if the equipment fails, you can save it with a controlled emergency ascent. To this end, he clasped his right hand to support the BCD of the Buddies and serves with his left hand in both his own and the equipment of the Buddies. The non- impaired diver passes the Notaufsteig. If the compressed air diving apparatus both Buddies work normally, then the emergency ascent made relatively easy. However, if one of the devices defective, the affected diver can with his buddy air from the second regulator line, the so-called octopus obtained. Alternatively, the two divers can also go to the alternate nostril breathing.
In advanced scuba diving training ( PADI Rescue Diver or CMAS ** ) of the controlled emergency ascent is practiced. But one rises from 20 to 30 meters and immediately starts with a controlled emergency ascent. Due to the virtually non-existent base time the risk of DCI is relatively low. This exercise is in diving circles often called pensioners lift, because the diver should go without physical effort safely to the water surface.
Uncontrolled emergency ascent
The uncontrolled emergency ascent should only be used when a controlled emergency ascent is impossible. Reasons for this may include an insufficient supply of air in the compressed air bottle, defects of redundant systems (eg compressed air diving apparatus both buddies are defective ) or an unconscious diver. Is initiated the uncontrolled emergency ascent through the lead- shedding or complete filling of the BCD. Occurs from a depth of 30m so within a maximum of 15sec a shot through the water surface. Since all the recommended ascent rate is exceeded and decompression stops are not met, the risk of a ruptured lung and a severe decompression sickness is very large, but this may already be the case in an uncontrolled emergency ascent from shallow depths. Depending on the depth and bottom time prior accident, there is a danger to life due to nitrogen bubbles to form in organs or the circuit. After an uncontrolled emergency ascent, is strongly recommended to seek immediate local emergency medicine and first aid. Often the victims are initially in fine shape, but this can change very quickly, which is why many accident victims die or at the dive site.
Emergency ascent with a rebreather
Is a submerged submarine to maneuver or has a large water intrusion occurs, so the crew can save with a rebreather on the water surface when other rescue means are unavailable or fail. Through a lock or after the production of pressure equilibrium with the surrounding water and the flooding of the pressure hull, the crew leaves the submarine. By inflating the diving savior of carrier then drives the water surface. Most inflation is done by a small compressed air cartridge. The breath is produced chemically, for a time of about 15 to 45 minutes from a Kalkpatrone. The emergency ascent with a rebreather corresponds to an uncontrolled emergency ascent while scuba diving. Therefore, there are basically the same diving medical risks. Since a U- boat crew - unlike divers - has been mostly enriched no nitrogen in the body, the risk for decompression sickness is much lower.
Emergency ascent of an entire submarine
Can a submarine no longer be tared or is used for blowing the ballast tanks, no more energy available, so many U- boats, a CESA be performed. By chemical gas generators, the need for the diving cells Notausblasen gas.