D
- DAN
- see Divers Alert Network
- DCIEM
-
Defence and Civil Institute of Environmental Medicine (Toronto, Canada)
- DDC
- Deck decompression chamber: A twin-lock hyperbaric chamber suitable for surface decompression and emergency recompression. Large enough to hold at least two occupants, one of them lying down.
- dead man anchor
- A heavy weight used to control the rise of a lift bag after breakout, or to capsize it to prevent a runaway lift
- dead space or dead volume
- 1. The volume of a breathing apparatus which holds exhaled air, which is subsequently inhaled directly. without passing through a scrubber to remove carbon dioxide and without oxygen addition.
- 2. The volume of inhaled air, which does not take part in gas exchange either because it remains in the conducting airways or in alveoli that are poorly perfused.
- decant
- Transfer gas between cylinders by differential pressure. No energy is input, flow will stop when pressures equalised.
- decompression
-
Reduction in ambient pressure experienced by the diver during the ascent at the end of a dive or hyperbaric exposure, and the process of allowing dissolved inert gases to be eliminated from the body tissues during this reduction in pressure.
- decompression algorithm
-
Further information: Decompression (diving)#Decompression algorithms
Specified step-by step procedures used to calculate the decompression stops needed for a given dive profile. The algorithm can be used to generate decompression schedules for a particular dive profile, decompression tables for more general use, or be implemented in dive computer software.
- decompression buoy
- see DSMB
- decompression chamber
- Hyperbaric chamber used for decompressing divers and emergency therapeutic recompression.
- decompression illness
-
Illness caused by decompression. Includes decompression sickness and arterial gas embolism due to lung overexpansion barotrauma.
- decompression schedule
-
Further information: Decompression (diving)#Staged decompression and decompression stops
A specific ascent rate and series of increasingly shallower decompression stops that a diver uses to allow inert gases to be eliminated from the body tissues during ascent after a specific hyperbaric exposure, to reduce the risk of decompression sickness.
- decompression sickness
-
A condition arising from dissolved inert gases coming out of solution during decompression as bubbles in the tissues, organs and blood vessels of the body causing symptoms ranging from rashes to death.
- decompression stop
-
Further information: Decompression (diving)#Decompression stop
A pause during the ascent phase of a dive that a diver spends at a constant relatively shallow depth to allow safe release of inert gases from the body tissues to avoid decompression sickness.
- decompression tables
-
Further information: Decompression (diving)#Decompression tables
Printed cards or booklets that allow divers to determine a decompression schedule for a particular dive profile and breathing gas.
- decompression trapeze
-
also decompression bar
Further information: Decompression (diving)#Decompression trapeze
A horizontal bar or bars suspended at the depth of intended decompression stops by buoys used to make decompression stops more comfortable and more secure and provide the divers' surface cover with a visual reference for the divers' position.
- deep stops
-
Further information: Decompression (diving)#Thermodynamic model and deep stops
Decompression stops which are deeper than the deepest stops required by decompression algorithms using dissolved phase models.
- deep water blackout
-
Loss of consciousness caused by cerebral hypoxia on ascending from a deep breath-hold dive, when the swimmer does not necessarily experience an urgent need to breathe.
- dehydration
-
A condition where the water content of the body is reduced.
- demand helmet
- Diving helmet which provides gas supply flow only when the diver inhales.
- demand valve
-
Further information: Diving regulator#Demand valve
Mechanism for providing the user with breathing gas flow only when required.
- depth gauge
- A pressure gauge calibrated to measure depth as a function of ambient pressure.
- developed pressure
- The pressure of the compressed gas in a cylinder at a temperature other than the nominal temperature at which charging pressure is specified. Usually refers to pressure when fully charged at a variation in temperature.
- DGPS
- Differential Global Positioning System An enhancement to Global Positioning System that provides improved location accuracy. DGPS uses a network of fixed, ground-based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions.
- diffusion limited
-
Decompression hypothisis that the uptake and elimination of inert gas is limited by diffusion rates in the tissues
- diluent
-
also sometimes dil
Further information: Rebreather#Gas sources
Gas mixture used to dilute the oxygen in the loop of a closed circuit rebreather to a partial pressure suited to the depth.
- DIN fitting
-
also DIN valve, DIN thread
Usually refers to G5/8” x 14 tpi parallel thread fittings used to connect a cylinder valve to a filling connection or regulator first stage. Available in 200 bar and 300 bar versions which should only be inter-connectable in safe combinations.
- DIN plug
-
See also: Diving cylinder#Connection to the regulator
Screw in adaptor which can be used with many recent 200/240 bar DIN pillar valves to allow connection of Yoke regulators or filling whips.
- DIR
-
also Doing It Right
A holistic approach to scuba diving, which encompasses several essential elements, including fundamental diving skills, teamwork, physical fitness, and the use of streamlined and minimalistic equipment configurations.
- distance line
-
also penetration line or guideline
A line used by scuba divers as a means of returning to a safe starting point in conditions of low visibility, water currents or where pilotage is difficult.
- dive computer
-
also decompression computer
A device used by a scuba diver to measure the time and depth of a dive so that a safe ascent profile can be calculated and displayed so that the diver can avoid decompression sickness.
- dive flag
-
Flag used to indicate that there are divers in the water. There are two versions: the international code letter flag 'Alpha', and the red flag with white diagonal bar, .
- divemaster
-
A professional level recreational diver who leads a group of less experienced or visiting divers underwater.
- dive profile
-
The variation of depth with elapsed time during a dive, often depicted as a graph.
- dive tables
- see decompression tables
- dive time
- The total elapsed time spent underwater during a dive.
- dive timer
- An automatically operated electronic timer which records the elapsed time from the start of a dive.
- diver transfer chamber
- Hyperbaric chamber connecting other component chambers of a saturation life support system which may be at different pressures.
- Divers Alert Network
-
also DAN
A non-profit organization for assisting divers in need and medical research on recreational scuba diving safety.
- diver's attendant
-
also dive tender
Person who assists the working diver to prepare for a dive, get in and out of the water, and to undress from the diving equipment, and who tends the lifeline or umbilical while the diver is underwater.
- diving bell
-
A rigid chamber suspended from a cable and used to transport divers to depth and back to the surface.
- diving chamber
- 1. A simple form of submersible vessel to take divers underwater and to provide a temporary base and retrieval system in the depths (diving bell).
- 2. A land or ship-based hyperbaric chamber to artificially reproduce the hyperbaric conditions under the sea.
- diving contractor
- Legal persona responsible for commercial diving operations.
- diving regulator
- see regulator
- diving signals
-
Hand sign and light sign system used by scuba divers to communicate when underwater.
- diving superintendent
- Person with overall responsibility for commercial diving operations at a large installation.
- diving supervisor
-
Person in charge of, and responsible for safety of a commercial diving operation.
- diving stage
-
also known as the basket
Further information: Decompression (diving)#Diving stages and wet bells
A platform on which a diver stands which is hoisted into the water, lowered to the workplace ot the bottom, and then hoisted up again to return the diver to the surface and lift him out of the water.
- DMAC
- Diving Medical Advisory Committee: An independent body of diving medical specialists from Northern Europe which provides advice about medical and certain safety aspects of commercial diving..
- DMT
- Diving medical technician: A paramedic specialising in diving related conditions.
- dome port
- A domed window of optical quality glass or plastic which covers the front of an underwater camera or video housing.
- Doppler bubble detection
-
Further information: Decompression (diving)#Doppler ultsasonic bubble detection
Ultrasonic signals reflected from bubble surfaces to identify and quantify gas bubbles present in venous blood.
- down time
- Period when planned activities can not be done due to unforeseen or uncontrollable circumstances.
- DP alert
- Status of the dynamic positioning system regarding positional accuracy and reliability. Green indicates normal operation, yellow indicates degraded operation and red indicates emergency.
- DP footprint
- Dynamic positioning footprint: The area around the nominal position to which a dynamically positioned vessel is constrained by the DP system.
- D-ring
- A ring shaped like a capital D, usually of stainless steel, stitched or buckled to a diver's harness and used as an attachment point for lifeline, cylinders or other equipment.
- Dräger tube
- Draeger tube
- Indicator tube used for testing breathing gas quality.
- drift diving
-
Any dive where the diver is transported significantly by drifting with currents during the dive.
- drillship
- Ship built or converted for offshore well drilling, using dynamic positioning to maintain position in deep water.
- drowning
-
The process of experiencing respiratory impairment from submersion/immersion in liquid.
- dry bag
-
Bag which seals in a watertight manner. Used for keeping clothes and other equipment dry in a wet environment.
- dry bell
- see closed bell
- dry suit
-
A watertight suit worn to keep the diver dry and to provide protection from the environment. Thermal insulation may be provided by the suit or garments worn under the suit.
- DSV
- 1. Dive/Surface valve: Valve on the mouthpiece of a rebreather which can be switched between the loop and ambient air at the surface.
- 2. Diving support vessel
- DSMB
-
also delayed surface marker buoy
An inflatable marker buoy deployed from underwater to indicate the position of a diver and to control ascent rate. Can also be used to mark a position or signal an emergency.
- duckbill valve
-
A valve, manufactured from rubber or synthetic elastomer, and shaped somewhat like the beak of a duck. Used as exhaust valve in some twin-hose diving regulators
- dynamic positioning
- Method of keeping a diving support platform in position without anchoring, using thrusters and positional feedback.
- dysbarism
-
Medical conditions resulting from changes in ambient pressure.
Read more about this topic: Glossary Of SCUBA Diving