|
Manual CCRs
The manual
CCRs are very simple machines. Some are totally manually flown, and some of
the most common – like the KISS on the picture – has a help valve that will
assist
replenishing
the loop with fresh oxygen at a preset level. This works more or less like
an active flow semi-closed rebreather, were you estimate your body
metabolism prior to diving (normally 0.6 – 1.0 litres/minute). The oxygen
flow is set by adjusting the interstage pressure on the oxygen 1st stage. If
you have to work harder or make a rapid ascent, this will affect
the PO2 level in the loop
and you will have to add oxygen manually. The unit can still be monitored
electronically with the “standard” set of three oxygen sensors, like the
KISS.
The idea for purchasing this kind of unit is off cause the economical point
of view, a KISS will cost you around 4.700 €, fully equipped with sensors,
wing, back plate, harness, etc. Another point of view could be to keep it as
simple as possible.
The main faults of these kinds
of units are the common lack of visual and acoustic alarms.
And there is not much price difference when you compare the real prices (including
all loose parts you need to be able to take it diving). |
