The scrubber system on a rebreather removes the carbon dioxide from the exhaled gas in the rebreather loop. Although the material used is referred to as an “absorbent”, CO2 is actually “scrubbed” by a chemical process. This process changes the CO2 from a gaseous state into several other chemicals that are not in a gaseous state.Absorbent effectiveness is dependant on several factors, a few of which are:
- specific chemical used
- size , shape or configuration of the granules or cartridge
- age or date of manufacture
- storage conditions
- dwell time, which is controlled by flow of gas around the loop
- temperature of the water dived in
- depth of the dive
- volume of O2 metabolized
- volume of CO2 produced, conversion rate can vary between .6 and .9
Manufacturers of rebreathers normally state a recommended maximum dive times on a specific unit, utilizing a type or grade of absorbent on dives to a specific depth.The typical range tends to be 3 hours and in some cases as much as 6 – 8 hours.Although a sensor is manufactured for analyzing CO2 in a scientific setting, none have been placed on a unit in the field.The only sensors to date that have been integrated into a rebreather system senses the heat wave only and NOT actual use or usable life left in the product. Vigilance and caution is mandatory as CO2 even slightly elevated at depth will effect:
- judgement
- perception
- breathing rate
- response time
- other significant physiological / chemical changes which effect the diver and produce additional change
During your ccr course you will be given specific limitations for your specific ccr and the scrubber material you and your instructor choose to
utilize in the assembly.
These factors will be addressed in detail by the experienced instructorcourse inquiry
See also: choosing a ccr which has additional information regarding scrubber requirements and claims.