One of the problems inherent in any rebreather is the build up of moist as a result of the chemical process of removing carbon dioxide from the exhaled gas. The vapor does prevent dehydration and is very pleasant to breathe, but the problem is that oxygen sensors read lower than normal when they get damp. On the Pelagian DCCCR we placed the injection point of the diluent gas so that every time diluent is added it blows over the sensor faces. This accomplish two functions: The sensor faces are blown dry and you get an instant change in PO2 on your O2 displays giving you a chance to see if your sensors are reading correct or not. For example, if you have air in your diluent cylinder and you are in 20 msw, your display should read around PO2 0.63 ATA, (ambient pressure X 0,21). Verifying sensor readings can be done on any closed circuit rebreather, but typically only after purging the breathing loop three times. On the Pelagian it is sufficient to gently keep a low flow of diluent gas for a few seconds to displace the breathing gas surrounding the sensors to get your reading. This will save you a lot of diluent, especially on a deep dive.
Details
[ Working principle ] [ Sensor validation ]
[ Trim and balance ] [ Frame work ]
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