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The Dolphin is a simple, Semi-closed circuit rebreather, which recycles the breathing gas in a loop in which exhaled carbon dioxide is removed by a chemical absorbent, oxygen-enriched gas is added to the cleansed gas, and the fresh mixture is recirculated to the diver through a counterlung, or inhalation bag. By means of this simple method, which has been used by professional divers for a long time, a small cylinder of NITROX can be made to last many times the duration of standard open-circuit SCUBA.

Semi-closed Circuit - function
indolphin.jpg (26042 bytes)The diagram of the Dolphin shows the simple circuit the breathing gas takes from lungs to lungs. Exhaled gas is breathed out through the mouth piece which has non-return valves to stop it going into the inhalation side. From there it passes via the exhalation hose into the small exhalation bag (which is not shown in this diagram) which contains a simple water trap to catch minor leakage's and some of the moisture from the exhaled breath.

The exhaust valve allows excess pressure to be vented from the system when it builds up. The valve is being located in front of the soda lime canister so that only the exhaled gas with a higher level of nitrogen and carbon dioxide is exhausted, rather than the refreshed, oxygen-rich breathing gas. Surplus gas trickles out here on a relatively constant basis throughout the dive.

Upon leaving the exhalation bag, the gas passes through a scrubber canister, which contains sodium hydroxide (soda lime), an alkaline substance which reacts with the slightly acidic CO2 to give off heat, and which turns the soda lime to chalk. The heat warms the inhaled NITROX up, giving the diver the additional bonus of warm breathing gas.

Cleansed from CO2, the gas is refreshed with oxygen by the addition of NITROX from the gas cylinder, which enters the inhalation bag either through a calibrated flow valve, or through the lung demand bypass valve if the bag does not contain enough gas to supply a full breath. From the inhalation bag (or counterlung, as it is sometimes called) the fresh breath returns to the diver via the inhalation hose and back to the mouthpiece.

Dolphin principle
The Dolphin is a simple unit, which is easy to prepare, to dive and to maintain and based on the following principle:

• Semi-closed circuit
• Using NITROX breathing gas
• NITROX mixture between 32% and 60 % oxygen
depending on the diving depth
• Constant flow supplemented by a second stage
• CO2 absorption with scrubber canister
• Integrated Buoyancy Compensator

Dolphin duration
The dive duration of the Dolphin with a cylinder, 4 liters/200bar, depends on the diving depth and the mixture used:

• 0 to 17 msw 125 min with 60% O2 and 40% N2
• 0 to 22 msw 95 min with 50% O2 and 50% N2
• 0 to 30 msw 67 min with 40% O2 and 60% N2
• 0 to 40 msw 47 min with 32% O2 and 68% N2

Dolphin advantages
Summary of the Dolphin advantages compared to open circuit compressed air:

• reduced gas consumption up to 95 %
• reduction of inert gas in the breathing mix
• safer decompression
• longer no decompression time
• decreased narcosis in recreational diving range
• silent and bubble-reduced operation
• breathing with no change of buoyancy
• longer thermal balance
• caused by heat generated in scrubber canister
• smaller than traditional Scuba systems
• safe operation in recreational diving due to pre-mixed gases

Data and Facts:

Operating principle: Semi-closed rebreather for Nitrox with constant mass flow, fresh gas enrichment and additional demand bypass. Carbon dioxide absorption with sodalime cartridge.

Sodalime: Dräger DiveSorb, approx. 2.25 kg

Breathing bag: Total volume: approx. 10.5 liters, movable volume: approx.4.5 liters, max 7.1 liters

Positive pressure valve: Opening pressure between 18 and 25 mbar

Cylinder: 27 Cubic Foot, 3000 psi

Dimensions/weight: Length 520 mm, width 370 mm, depth 235 mm on land: approx. 17 kg/37.5 lb in water: approx. -1 kg/-2.2 lb

Equipment: Sodalime cartridge, breathing bag, breathing hoses with mouthpiece, demand bypass, pressure reducer, backplate (with buoyancy compensator for Dolphin T 51 401), O2-suitable pressure gauge, flowmeter

Compressed air bailout system, sodalime DiveSorb, dosage device for 32/68, 4 L and 5 L mixed gas cylinders, buoyancy bladder (for Dolphin T 52 200), Oxygauge

Safety note:
Prior to purchasing a Dräger Dolphin Rebreather you must complete an approved rebreather course.

oxygauge.jpg (13893 bytes)DRAGER OXYGAUGE









Calium Hydroxide, Sodium Hydroxide, Water

Hemisperical Pellet


Water Content
16% ±2%

Tyler Mesh: 5-9

Packaging Size
DiveSorb® - Canister, 4.5 kg, 67 37 199
DiveSorb® - Canister, 18 kg, 67 37 108

Ascend to Surface