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RB80 Pool Training (June 2004)
Latest update: July 17, 2004
The rebreather divers are setting up their gear. The room was quite crowded as such a lot of equipment needs a lot of space. What you can see is the 'long' side of the pool.
Safety through knowledge
As even the best rebreather requires frequent training and further education of its users, all thirteen EKPP rebreather divers met in Düsseldorf for a refresher session on June 5th. Such training events are frequently scheduled within the EKPP in accordance with one of the basic principles of DIR diving: continuous improvement of skills and knowledge is a must.
Could you imagine more than ten rebreather divers, each equipped with double 20s around the rebreather, simultaneously in a pool of five by seven meters and less than two meters deep? Well it is possible! Due to the special goals of this training session the pool was perfect. Thanks again to Brus for organising it.
At first all rebreather setups were assembled and then checked by the whole team for any faults. So, for example, the perfect position of the Argon bottle was a point of discussion. In accordance with DIR principles, the general position was clear: on the left tank of the Double 20s. However, moving the argon bottle far enough downwards to archive a perfectly streamlined setup without disturbing the wing needs some deeper experience.
The whole group inspects the frames for any faulty setups. Even at almost thirty degrees Celsius, Sandro pretended to be a dress man.
After this, the divers dressed up and went into the water. They all went in with a defective rebreather! First goal was to dive the rebreather with a faulty mushroom valve on the interior counter lung. To simulate such a failure, the valve was simply removed. If this valve malfunctions, no gas is vented with each breath from the rebreather and therefore also no fresh gas is added. The result is a drop of oxygen in the loop, which will lead to hypoxia. If a diver suffers hypoxia, he will get unconscious without any kind of warning, which means almost certain death. Hypoxia was not possible during the training as the divers were closely supervised and breathing only pure oxygen. However, a guaranteed hypoxia would have sealed the diver's fate if he had been in open water under the same circumstances and breathing a gas other then oxygen. So during this part of the training it was important to learn to notice the different feeling of breathing while on a rebreather with a defective mushroom valve. To minimize the risks of an accident caused by a defective valve during a real dive, checking the functioning of your buddy's rebreather and especially the venting of gas through the dump valve is a mandatory part of the EKPP´s series of checks right after submerging.
To demonstrate a failure of the mushroom valve in the interior counter lung, the valve was removed. The result is that no gas is vented on each breath. A good dive buddy will notice immediately that there are no bubbles coming from his/her buddy's rebreather.
After all divers got a feeling how it is breathing with a defective valve under the watchful eyes of their dive partners, the scrubber was removed from the units and the valve was reinstalled. The purpose of the next exercise was demonstrating Hypercapnia due to a massive accumulation of CO2 in the loop. This could happen in real life for several reasons. The Sofnolime could have gone bad due to a defective canister or due to it being over-used. Also, a diver could forget to fill Sofnolime or reuse already used lime. However, these two points are excluded when adhering to DIR principles. Buddy awareness also means that while one dive partner assembles his rebreather the other one closely watches him and vice versa. Reusing used Sofnolime is definitely something you could grade as 'doing it wrong'. The last cause of Hypercapnia would be all the lime being used up due to a very long dive. As the RB80 has a rather large scrubber, this is only possible if dives last for more than ten hours.
The so-called 'Rentnertische' are a must if you dive a rebreather, as you can assemble your RB 80 and dress very easily. Silvia and Victor drove almost a thousand kilometres to participate in the training; Tom is a gentleman and helps Silvia.
Back in the water without the scrubber, the divers had to swim heavily against the wall of the pool while breathing pure Oxygen again. Because of the missing Sofnolime, CO2 was accumulated in the loop. Exertion helped to speed up the process. The goal of this exercise was to get acquainted with the symptoms of hypercapnia so that the divers will recognise these symptoms if they encounter them during a real dive.
During the lunch break, details of future projects were discussed. Afterwards the team went back to the pool for a refresher session on rebreather theory followed by the usual written exam. The last session of the day was the Hypoxia test. While during all previous exercises each diver was supervised by his/her dive partner, this time around two watchdogs were assigned to each diver while he/she performed the hypoxia test. Trimix 17/55 was plugged into the rebreather and a Dräger Oxygauge was installed to monitor the oxygen level dropping in the loop.
Chaled is not trying to push a hole in the wall of the pool. He is straining himself to produce CO2 during the Hypercapnia simulation.
As rebreather diving is much more dangerous than open circuit diving, continuous training and further education is a must. As the success of EKPP in cave diving is based on the strict application of DIR principles, frequent refresher training meetings are organised to maintain the highest possible level of knowledge and safety. Besides the fact that all this is pure fun, wearing a dry suit in twenty-five degrees Celsius water is an 'interesting' experience.
During the refresher session on rebreather theory, Reinhard and Michael were sharing the experience from their long (eighteen hour) rebreather dives.
Premiere of the infrared camera and the infrared light. As the light of the torch is out of the visible spectrum you can head mount it without the risk of blinding your dive partner. The camera (the recorder is in the housing) works perfect with this light. Due to the position on the head of the diver it gives you the impression of looking trough the eyes of the diver. Breathtaking!