Escape trunk

Escape trunk

An escape trunk is a small compartment on a submarine which provides a means for crew to escape from a downed submarine; it operates on a principle similar to an airlock, in that it allows the transfer of persons or objects between two areas of different pressure.

Principle of operation

The water pressure on the outer hatch is always greater than the air pressure inside the submarine, which prevents opening the hatch. Only when the pressure inside the escape chamber is equal to the sea pressure can the hatch be opened. Thus the compartment must be sealed off from the interior of the submarine and the pressure inside the chamber must be raised to sea pressure in order to make it possible to open the escape hatch.

Operation

#The drain valve is opened to ensure any residual water is drained from the compartment and the pressure between the interior of the submarine and the escape trunk is equalized.
#The drain valve is closed, 6–8 persons climb up through the lower hatch into the escape chamber, and the lower hatch is shut. Before climbing into the chamber, the escapees don a Steinke hood or Submarine Escape Immersion Equipment, which will provide an air supply during the ascent to the surface.
#The seawater valve is opened to flood the chamber. This water comes from the sea and its pressure is equal to the ambient ocean. As the chamber floods, the air in the chamber is compressed until its pressure is equal to the sea pressure. When the pressure in the chamber is equalized with the sea pressure, the flooding of the chamber will stop. The water level must rise above the level of the escape tube (see diagram). Additional air is vented into the chamber from the high pressure air supply to raise the air pressure. A bubble of air at the top of the chamber remains for the persons inside to breathe while awaiting their turns to exit the chamber.
#The first escapee’s Steinke hood is filled with air from a hose attached to the high pressure air line before departing. Pressure in the hood must be equalized with ambient air/water pressure. The first escapee climbs up through the escape tube and pushes the hatch open. The hatch could not have been opened until the interior pressure of the chamber was equalized with sea pressure. Once outside the chamber, the buoyancy of the air inside the Steinke hood will quickly carry the escapee to the surface. As the person rises to the surface, the ambient water pressure decreases and thus the air in the person’s lungs and in hood expands. Thus escapees must continuously exhale all the way to the surface to release the expanding air from the lungs.
#One by one, each escapee’s Steinke hood is filled with air and the person climbs out the escape tube and rises to the surface. The last man out must push the outer hatch shut before departing.
#Inside the submarine, the drain valve is opened to drain the water from the chamber and equalize the pressure to that within the submarine. The pressure inside the chamber will quickly force all water from the chamber out the drain valve. Lowering the pressure inside the chamber will also force the outer hatch shut again because of greater sea pressure outside the submarine. Then the cycle begins again until everyone has left the submarine.

DSRV rescue

The escape trunk can also be used for the rescue of a crew inside a disabled submarine using a Deep Submergence Rescue Vehicle (DSRV). The crew of the DSRV will maneuver the vessel above the upper hatch of the escape trunk and then latch on to the submarine using the built-in eyes on the outer hull of the submarine. Most submarines do not have the built-in eyes and rely on the DRSV establishing a watertight seal on the area surrounding the hatch. Once the sub has settled on the correct location the skirt is pumped out and the hydrostatic pressure on the exterior of the skirt is enough to maintain the seal when the hatches are opened and the transfer undertaken. The crew can then quickly equalize the pressure in the small chamber between the DSRV and the submarine and open their own lower hatch.

On the outside of the upper hatch of the escape trunk is often a shaft connected to the wheel that operates the locking mechanism. The crew of the DSRV can attach a wheel to the shaft and turn the shaft to unlock the hatch, thus providing access to the interior of the submarine. This is a potentially risky operation, as when a submarine has been damaged enough to sink it is possible there was an ingress of water into the pressure hull raising the internal pressure above the normal 1 bar.

Notes

*A sequence using an escape trunk and a DSRV was shown in the 1990 film "The Hunt for Red October".


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • escape trunk — A vertical trunk fitted with a ladder to permit personnel to escape if trapped …   Dictionary of automotive terms

  • trunk — The storage compartment of a vehicle. In older cars, a large suitcase (or trunk) was strapped to the back of the vehicle. In rear engine vehicles, the trunk is located in the front of the vehicle (e.g., Volkswagen); but generally it is located at …   Dictionary of automotive terms

  • Trunk to Cairo — (1966) is an Israeli/West German film produced by American International.PlotMike Merrick (Audie Murphy) is an American agent who is sent to meet with Professor Schlieben (George Sanders) a German scientist. During the mission it is revealed that …   Wikipedia

  • Submarine Escape Immersion Equipment — (SEIE) MK 10, also known as Submarine Escape and Immersion Equipment is a British designed whole body suit and one man life raft that allows submariners to escape from a sunken submarine. The suit provides protection against hypothermia and is… …   Wikipedia

  • Ford Escape Hybrid — Infobox Automobile name=Ford Escape Hybrid manufacturer=Ford Motor Company production=2004 ndash;present class=Compact SUV body style=4 door SUV platform=Ford CD2 platform layout=Front engine, front wheel drive / four wheel drive assembly=Kansas… …   Wikipedia

  • BAP Pacocha (SS-48) — was a submarine of the Marina de Guerra Peruana (Peruvian Navy) named for the 1877 Battle of Pacocha, in which the Peruvian ironclad Huascar clashed with the Royal Navy. Formerly USS|Atule|SS 403, a Balao class submarine with a GUPPY IA upgrade,… …   Wikipedia

  • Momsen lung — A Momsen lung in use during training The Momsen lung was a primitive underwater rebreather used before and during World War II by American submariners as emergency escape gear. The Momsen lung was invented by Charles B. Momsen (nicknamed Swede… …   Wikipedia

  • Submarines in the United States Navy — There are two major types of submarines in the United States Navy: ballistic missile submarines and attack submarines. In the U.S. Navy, all combatant submarines are nuclear powered. Ballistic subs have a single, strategic mission: carrying… …   Wikipedia

  • USS Scorpion (SSN-589) — was a Skipjack class nuclear submarine of the United States Navy, and the sixth ship of the U.S. Navy to carry that name. Scorpion was declared lost on June 5, 1968,cite web |date=2007 |url = http://www.submarinehistory.com/Scorpion.html|title =… …   Wikipedia

  • USS Archer-Fish (SS-311) — For other ships of the same name, see USS Archerfish. Career …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”