Quote: (Originally Posted by
jmurba)
my first kiss dives attempts were done on the same orifice then the first gordon smith orifice, the IP for 0.8 lt/minute was 7 bars !!!
I dived it down to 50m without a shadow of a problem,
of course due to the fact that the orifice was not sonic anymore I had to face a flow rate cut but ok It still worked fine.
like gordon was saying "for the time one spend in 60m even a dil flush would be enough to maintain the ppo2 level"
what I mean is that the dogma of the sonic flow is too limiting.
if you read the jacques vettier book about rebreathers you will find out tests and charts showing that getting a sonic flow is nice but that the flow rate drop is not so dramatic when you get a bit under the 2.00 ratio.
the sonic depth is not an absolute limit under wich you will not have o2 anymore, it is more subtile then that, it can be exceeded.
personly I use an hydrogom with 11 bars for 0.8 lt/mn and dive it down to 65-70 m and I have never noticed any need for injecting manualy more often.
last thing, swagelock website provides a flow rate simulator where one can tests all of that, orifices and needlevalve have different reactions
regards
jean mi
you are right jean
you do not need sonic flow if your are prepared to work a bit more,
i just wanted to raise awareness that when you plan to build a hyprid your intention is normally that you rely on the eCCR to add some O2 form time to time. As the IP /ambient pressure ratio for the solenoide reduces at the same time the eCCR might not be able to inject suffcient amount of O2 into the loop anymore, depending on its cycle time. This could be dangerous as he might get used to teh eCCR taking over at shallower depth, and not realizing the solenoide not doing its job anymore, particlar when acscending form 50 meters forgetting to pump up the pO2 on ascend.
I am quite often ending at 55 meters, this would leave me only 1 bar ip over ambient, pretty slim.