Rebreather Hints/advice

[up 4 it]

Hi All

Thought I'd start this thread so we can help educate each other by our learning and experience as to what pitfalls there are when diving a RB, and how we can overcome/avoid them.

Some might seem quite obvious, others not so obvious, but lets see if we can come up with a comprehensive guide of do's and dont's.

Steve

I'll start the ball rolling with a couple

1) If you get a low PPO2 warning on the RB don't attempt to surface or ascend whilst breathing the loop. The reason being he PPO2 will drop considerably as you ascend, and what was initially a PPO2 of 0.4, may drop in seconds to 0.16 or below causing hypoxia and then anoxia = Death

Initially try to inject O2 manually (the solenoid may have shut closed), see if that raises it, if it doesn't do a Dil flush, revert to SCR techniques or bail-out to OC and slowly ascend.

2) Consider fitting an off-board O2 cylinder connected to the manual O2 inject valve, and running the solenoid only off the in-board. that way if you get the solenoid stuck open you can manually shut down the in-board, flush the loop, and the still be able to inject O2 manually without the need to continually crack open/shut the in-board O2 cylinder. You the also have redundancy with a second cylinder in case the first one runs out for whatever reason during the dive.

[Phoenix]

Originally Posted by up 4 it

<snip>

2) Consider fitting an off-board O2 cylinder connected to the manual O2 inject valve, and running the solenoid only off the in-board. that way if you get the solenoid stuck open you can manually shut down the in-board, flush the loop, and the still be able to inject O2 manually without the need to continually crack open/shut the in-board O2 cylinder. You the also have redundancy with a second cylinder in case the first one runs out for whatever reason during the dive.</snip>

The danger with this kind of thread is that the information given can be unit specific, if you followed the procedure above on the boris then the O2 from the O/B cyl would still be fed to the solenoid, the solenoid isolation valve would have to be closed to achieve the aim. At this time the only non-trained boris user is the P.O.S who has my stolen unit in future it may be some decent person and I wouldn't want them to have an incident due to incorrect information picked up online.

Ian

[Alan]

1) If you get a low PPO2 warning on the RB don't attempt to surface or ascend whilst breathing the loop. The reason being he PPO2 will drop considerably as you ascend, and what was initially a PPO2 of 0.4, may drop in seconds to 0.16 or below causing hypoxia and then anoxia = Death

Initially try to inject O2 manually (the solenoid may have shut closed), see if that raises it, if it doesn't do a Dil flush, revert to SCR techniques or bail-out to OC and slowly ascend.

2) Consider fitting an off-board O2 cylinder connected to the manual O2 inject valve, and running the solenoid only off the in-board. that way if you get the solenoid stuck open you can manually shut down the in-board, flush the loop, and the still be able to inject O2 manually without the need to continually crack open/shut the in-board O2 cylinder. You the also have redundancy with a second cylinder in case the first one runs out for whatever reason during the dive.

3) Have a list of your equipment checks laminated and with you when you put it together, tick each one off. This will help eliminate any problems which might arise from being rushed or tired.

4) If you ever feel like you are swmming through treacle, to the drop off, DO NOT DESCEND-CO2 is upon you. Flush the loop if you can and get out of the water ASAP.

[gibbon]

Is this list going to be designated for Inspirations?

If not then point 2 is meaningless for Megalodons as well as Oroborus(es).

That is not to say that the list is not an excellent idea, just perhaps if a point is unit specific it should be clearly identified as such.

1) If you get a low PPO2 warning on the RB don't attempt to surface or ascend whilst breathing the loop. The reason being he PPO2 will drop considerably as you ascend, and what was initially a PPO2 of 0.4, may drop in seconds to 0.16 or below causing hypoxia and then anoxia = Death

Initially try to inject O2 manually (the solenoid may have shut closed), see if that raises it, if it doesn't do a Dil flush, revert to SCR techniques or bail-out to OC and slowly ascend.

2) Consider fitting an off-board O2 cylinder connected to the manual O2 inject valve, and running the solenoid only off the in-board. that way if you get the solenoid stuck open you can manually shut down the in-board, flush the loop, and the still be able to inject O2 manually without the need to continually crack open/shut the in-board O2 cylinder. You the also have redundancy with a second cylinder in case the first one runs out for whatever reason during the dive.

3) Have a list of your equipment checks laminated and with you when you put it together, tick each one off. This will help eliminate any problems which might arise from being rushed or tired.

4) If you ever feel like you are swmming through treacle, to the drop off, DO NOT DESCEND-CO2 is upon you. Flush the loop if you can and get out of the water ASAP.

5) Keep a record of your scrubber utilisation and be sure not to exceed what you know to be safe.

[up 4 it]

Sorry guys, point taken, should have specified that the off-board O2 was aimed at Inspo as that's what I dive.

Steve

[NotDeadYet]

Isn't this stuff that should either be covered in training or that a RB diver should already know? It's a little worrying to think that there are rebreather divers out there having a religious experience at the revelation that you shouldn't ascend with a low pO2 or should bin the dive if the scrubber doesn't feel right.

[The_Ferret]

Originally Posted by Phoenix

The danger with this kind of thread is that the information given can be unit specific, if you followed the procedure above on the boris then the O2 from the O/B cyl would still be fed to the solenoid, the solenoid isolation valve would have to be closed to achieve the aim. At this time the only non-trained boris user is the P.O.S who has my stolen unit in future it may be some decent person and I wouldn't want them to have an incident due to incorrect information picked up online.

Ian

I quiet agree ... and steve,you havent had your rebreather 12mths yet

probably less than 6mths, so giving out advice.. seems very dangerous considering your lack of experience !!!!

john..........

[up 4 it]

John

6 mths, or 6 years it doesn't make any difference if the advice is good.

If you don't have anything of relevence to say then don't bother. As an instructor trainer and diver with over 19yrs experience I feel that I'm in a position to offer some advice/refresher info on various matters.

I've started this thread for people to offer their advice for the benefit of all. When you learn to dive properly maybe you could do the same. Anyway you don't dive rebreathers so you have nothing really to add.

[up 4 it]

Originally Posted by NotDeadYet

Isn't this stuff that should either be covered in training or that a RB diver should already know? It's a little worrying to think that there are rebreather divers out there having a religious experience at the revelation that you shouldn't ascend with a low pO2 or should bin the dive if the scrubber doesn't feel right.

Don't be such a nob,

The reason I brought up the low PPO2 ascent was that a diver who died recently may have done so because of this very fact. He didn't have a bailout cylinder and continued to breathe from the loop at the surface with a very low PPO2 and passed out.

None of us know everything and therefore we should try and learn from each other, because once you've completed your courses you're out there on your own. Perhaps a little more education may help to prevent a few deaths.

[Janos]

I'm not sure of the value of this thread either. This stuff is duplicated elsewhere on the internet, and unless this thread is meant to be a comprehensive guide to rebreather diving (in which case it would be massive) then I don't see the point.

If there is something new to be learnt from an incident then fair enough, but I can't see the point in a thread that tells me to check my ppO2.

Janos