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The main difference between Open Circuit Scuba or Semi-Closed Circuit Rebreather diving and a Closed Circuit Rebreather, is that it maintains a constant P02 during the dive. This means that instead of planning a mix for a given depth, the rebreather constantly changes the mix to suit the depth you are at. This way the system is continually changing the 02 content to maximize 02 levels, and therefore minimize N2 levels. There is an increase of about 10% dive time over conventional OC (Open Circuit) or SCR (Semi-Closed Rebreather) Nitrox diving. Naturally the CCR (Closed Circuit Rebreather) is a more complicated piece of equipment and requires more involved training, but it isn't beyond the realms of most competent divers. If you hold an Advanced Nitrox Diver certification and have good buoyancy control and discipline, then CCR (Closed Circuit Rebreather) diving should not be too difficult. The Inspiration Closed Circuit Rebreather is the first CE approved closed circuit breathing system approved to 50 metres with Air as the diluent gas (40 metres recommended) and 100 metres with Heliox. The dual microprocessor oxygen-level controllers automatically maintain a constant partial pressure of oxygen giving outstanding gas duration and an optimum breathing mix at all depths. With No-stop times dramatically increased, the benefits of perfect buoyancy control, warmer, quieter diving and bubble free operation allowing really close wildlife encounters the Inspiration closed circuit rebreather is revolutionising diving today, offering a whole new experience to Sport and Commercial divers worldwide. What do you get with the Inspiration Classic ? The full spec Inspiration includes: 2 x 3 litre cylinders, one for oxygen, one for diluent (air or Trimix) with contents gauges for both. Two over-the-shoulder counterlung breathing bags - inhalation and exhalation. Mouthpiece and breathing loop hoses with hose-weights and built-in water-traps. A carbon dioxide Scrubber unit. A computerised Oxygen Controller system consisting of two micro-processor control units with digital displays and separate power supplies, three oxygen cell sensors and a solenoid oxygen injection valve. A specially designed harness and 16kg wings style Buoyancy Control Device with an Auto Air - emergency demand valve / jacket breathing valve / inflator - fitted. Manual diluent and oxygen feeds to the left and right counterlungs. There are two sizes of counterlungs, M or L and three sizes of harness, S, M, and L. How does the Inspiration Classic work ? The Inspiration is a closed circuit system which means that the breathing gas is continuously recycled in a closed loop. This is in contrast to conventional open circuit diving in which the bulk of the exhaled breath is wasted by venting it out into the surrounding water. With the Inspiration Closed Circuit exhaled air is directed into the right hand counterlung then over the shoulder into the bottom of the scrubber unit. It then passes through a Sofnolime filter which absorbs the carbon dioxide before entering a mixing chamber where 3 individual oxygen sensors measure the partial pressure of oxygen (ppO2). The electronic controller is a voting logic system which automatically instructs the solenoid to inject oxygen into the mix to replenish the oxygen the diver has metabolised and maintain the ppO2 at the chosen Setpoint. The replenished breathing mix passes into the inhalation counterlung to repeat the cycle. How does the Inspiration Classic compare with open-circuit scuba ? The Inspiration is about 75 times more gas efficient at 20m than open circuit, rising to at least 100 times more efficient at 40m. How long can I stay underwater with the Inspiration Classic ? Dive duration is limited by the CNS oxygen toxicity clock and the life of the CO2 Scrubber. The oxygen exposure limit varies according to which Setpoint ppO2 is selected. The Inspiration has two default Setpoints - 0.7bar and 1.3bar - and these can be altered in Menu Mode to setpoints ranging from 0.5bar to 1.5bar. Therefore you can tailor the setpoint to suit the mission. To give some examples:- working to the NOAA Exposure Limits - at a Setpoint of 1.3bar dive duration is limited to three hours (or three and a half hours per day). However, if you wanted to increase duration you could dive, for example, on a setpoint of 1bar and increase your ox-tox exposure limit to five hours. What is the duration of the CO2 Scrubber ? The duration of a Sofnolime fill depends upon factors such as the individual diver's CO2 production rate, water temperature, work rate and so on. In the recent independent testing for CE certification carried out at the Ministry of Defence Research Establishment, Alverstoke, the Inspiration's scrubber duration was 3 hours in cold water (4 degrees C). The tests simulated a breathing rate of 40 litres per minute (lpm) RMV, and a CO2 production rate of 1.6 lpm. How long will each fill of the Oxygen cylinder last ? By recirculating the exhaled gases, removing the CO2 waste product and replenishing the oxygen the Inspiration limits the gas removal from the oxygen cylinder to the same volume that we consume for metabolism. That is, between 0.5 and 3.5 litres per minute depending on the person and the work rate. Mr Average consumes approximately 1 litre of oxygen per minute and in general, women consume less. Filled to 200 bar the Inspiration's 3 litre Oxygen cylinder contains 600 litres of oxygen. Therefore, at the average consumption rate of 1 lpm, theoretically, each fill should last 600 minutes or 10 hours. In practice some gas is lost during mask clearing and extra O2 is added during ascents. Nevertheless, it is realistic to achieve at least 6 hours diving from one 3 litre cylinder of oxygen! What training is required to dive with the Inspiration Classic ? The Inspiration Closed Circuit is a specialist piece of diving kit. Units will only be sold to divers who have successfully carried out a suitable training course. At present, training is carried out under IANTD, TDI, IART, BSAC, ANDI or RAB guidelines. What happens if you drop the mouthpiece underwater ? The Inspiration mouthpiece is designed so that it can be closed - by rotation of the body section - and sealed water-tight before removing from the mouth whilst in the water. If the mouthpiece is removed without closing it first, water may enter the loop. The Inspiration is very tolerant of small quantities of water entry as there are a series of water-traps and barriers throughout the loop but allowing in excessive quantities should be avoided in the first instance by correct practice. The actions to take in case of water entry depends upon the circumstances leading up to the situation and how much water has entered. Any water entering via the mouthpiece is forced into the right hand counterlung by a trap at the top of the breathing hose. Depending on how much has been allowed in, it is perfectly reasonable to continue the dive leaving water in the bottom of this lung. Obviously, if you continue to dive head-down, or perform somersaults, you will risk some water finding its way past this first trap. Even if this happens, there is the combination of another water-trap and an hydrophobic membrane at the bottom of the scrubber unit to inhibit entry into the Sofnolime cartridge. In addition there are two further water-traps at the top of the scrubber unit and at the top of the inhalation counterlung. Therefore, all in all, the Inspiration is designed so as to make it extremely unlikely that a sufficient quantity of water could enter via the mouthpiece, completely circumnavigate the loop and return to the inhalation side to threaten any kind of 'caustic cocktail' situation. To get to such a situation would require both poor dive practice in the first place in allowing a large quantity into the mouthpiece and then continuing the dive with a complete disregard of the warning signs which become apparent if excess water has come into contact with Sofnolime - warnings which do allow plenty of time to take the appropriate actions. The golden rule is of course, if in doubt, bail-out and the Inspiration has an integrated emergency breathing system which allows for a simple bail-out to open circuit if necessary. (See bail-out options below) What happens if oxygen tolerances are exceeded ? All 3 oxygen sensor readings are displayed simultaneously in real time on both Master and Slave controller display units which allows you to see sensor movements and easily monitor their health. Sensor validation is also carried out by the controller software and an audible warning sounds if an individual sensor strays abnormally. Both high and low ppO2 levels activate the audible alarm - that is, at a high point of 1.6 bar and a low of 0.4 bar. These levels allow reasonable time to take appropriate action - such as, manually inject either oxygen or diluent or to bail-out to open-circuit. What happens in the event of an electrical breakdown ? There are two independent control systems: one Master and one Slave. Whichever one you turn on first is the Master. Both have their own power supply. In the event of the Master shutting down, the Slave instantly - within 0.06 seconds - becomes the Master and controls the ppO2 in the loop automatically. Normally the Slave is a simple secondary display using the same three oxygen sensors as the Master. However, it uses its own calibration factors and is completely independent of the Master and so can be used to validate the Master. Both displays can be used as a simple ppO2 monitor, allowing you to manually operate the oxygen or diluent valves if required. What emergency 'bail-out' options are there ? During a dive very little diluent gas should be used. Typically only about 30 or 40 bar from the 3 litre cylinder. The diluent cylinder provides gas for counterlung volume during the descent, for lung volume adjustments throughout the dive , for BC inflation and for dry-suit inflation. As gas consumption is so small a large proportion of the 3 litre cylinders remain for open circuit bail-out. To take advantage of the diluent reserve, an Auto Air - emergency demand valve / inflator - is fitted to the BC. The bail-out procedure to open-circuit diluent therefore is simply a question of swapping the Inspiration mouthpiece for the Auto Air to breathe directly from the diluent cylinder. [NB: The Inspiration mouthpiece is designed so that it can be sealed to prevent flooding of the unit when taken out of the mouth.] The Auto Air is also an emergency jacket breathing valve. [An alternative to the Auto Air would be to fit an Octopus 2nd stage - provided it is a down-stream type that will function as an over-pressure valve.] Another bail-out option is to fit an oxygen-clean 2nd Stage (with isolator valve) for emergency breathing of pure O2 from the oxygen cylinder at 6m and above. The volume of bail-out gas available is as much a limiting factor to your dive planning as the gas configuration selected. You must ensure you have sufficient volume of breathable open-circuit gas available at all stages of the dive. How do I know the sensors are working properly ? All 3 oxygen sensor readings are displayed simultaneously in real time on both controller display units which allows you to see sensor movements and easily monitor their health. Sensor validation is also carried out by the controller software and an audible warning sounds if an individual sensor strays abnormally. Whe was the Inspiration Classic officially tested and approved ? In the spring of 1997 the then named Buddy Inspiration underwent extreme and rigorous independent testing by the British Government's MOD Defence Research Agency (DRA) at Alverstoke and a further series of manned and unmanned equipment tests by the Societe Generale de Surveillance (SGS) UK Ltd - International Certification Services. Tests included among other things, breathing performance, oxygen setpoint control, CO2 scrubber duration, tensile strengths, flow rates, performances at different temperatures and open-water trials. The aim was to achieve the desired and obligatory CE approved certification and we are proud to report that the Inspiration sailed through all of this with flying colours. In fact observers report that the unit frequently performed so well that it caused the testing supervisors to check whether their equipment was actually working properly! The Inspiration actually set new standards for the industry in terms of both the accuracy of the oxygen controller and the duration of the CO2 scrubber. The Royal Navy had never before seen an oxygen controller that could maintain the partial pressure of O2 at the mouthpiece so close to the constant ppO2 setpoint...within +/- 0.02 Bar! Similarly, the Inspiration CO2 Scrubber was the most efficient system that they had come across to date. Tested in cold water (4 degrees C), they simulated a breathing rate of 40 RMV and CO2 production rate of 1.6 litres per minute - which is about twice the rate most people produce - and even in these conditions, the Scrubber achieved a duration of 3 hours. |
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