Hook up of bailout gas to BOV
- Thread starter Sharkjaw
- Start date
zirk
New Member
Thanks for the pics Tim. I can see you put a lot of time, thought and $$$ into your plumbing project. Good job! My only comment ( not criticism ) is that it looks complicated. In an emergency situation in stress would you push, pull , turn the correct turn offs/turn ons and knobs?
I'm like you I love to tinker with my gear. I find it relaxing.
Z.
I'm like you I love to tinker with my gear. I find it relaxing.
Z.
Tim1
Member
Hi Zirk,
Sure, operation is a degree of complexity on from just ditching the loop and grabbing a bail-out regulator. However look at it from the perspective of solo underwater photography and being able to bail, via BOV, to a usable supply of breathable gas at any depth (2 x 7 litre on-boards and 2 x 7 or 11 litre off-boards). Lets look at some scenarios:
Bailing off the loop at the deep end of the dive.
1. Switch BOV to OC - now breathing off seven litres of dil. Commence ascent.
2. Monitor dil pressure and shut down dil when a useful reserve pressure remains. Check valve operates and gas supply to BOV switches to left side deep off-board BO
3. At MOD of right side shallow off-board (EAN 50). Flick gas block lever to 'up' - now breathing off shallow BO. Here its a good idea to also shut down the on-board O2 so that you know absolutely the only gas you can be breathing is the shallow off-board BO and you are not relying on the check valve.
4. At 6 metres, open the on-board O2 and shut down the shallow off-board BO - now breathing off seven litres of O2.
Bail-out to SCC
Just the same as above with the exception that I can 'sniff' gas from the TX100 and inject it into the loop through the FFM mouthpiece. Access to all four gasses allows me to remain on SCC all the way to the surface as I retain control of the PO2. Outside of any emergency procedures, the ability to adjust loop volume by inhaling or exhaling dil through the TX100 is a boon. As a photographer I tend to be making many depth changes throughout the dive, looking for angles and composition. I find it expedient to make micro buoyancy compensations using the loop.
02 boom or solenoid failed open or closed
1. Shut down O2 and dil flush if required
2. Isolate primary O2 supply to MAV with slider
3. Turn on redundant O2 and fly manually
4. Continue with dive?
LoC and a buddy rescue.
The only gas management procedure that is required is to flick the switch block lever to 'up' at the MOD of the shallow off-board BO. All other gas switches (dil to deep off-board and shallow off-board to O2) operate automatically via check valves on primary gas shut down or depletion.
Hope this helps, Tim
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zirk
New Member
How does the desent work? Also do you have pressure relief valves on your first stages for IP creep as it sounds like deep and shallow on board and off board gasses might be connected and open to each other at certian times? I like the concept of the gas switching block, but at the samne times it worries me.
I can only have one off board gas connected to my BOV at a time. I do have the option of running my off board through my rebreather by plumbing it through the dill first stage (Can also send it through my MAV). So in case of a dill boom, I can shut off my dill and turn on the off board and it goes through the rebreather via the firsr stage. My set up was derived from Dave Sutton's (can I mention his name?) Video on bail out plumbing.
Z.
Z
I can only have one off board gas connected to my BOV at a time. I do have the option of running my off board through my rebreather by plumbing it through the dill first stage (Can also send it through my MAV). So in case of a dill boom, I can shut off my dill and turn on the off board and it goes through the rebreather via the firsr stage. My set up was derived from Dave Sutton's (can I mention his name?) Video on bail out plumbing.
Z.
Z
Tim1
Member
With all four gasses plumbed all I need to do on descent is to flick the gas switch block lever to 'down' before I exceed the MOD of my shallow off-board BO. In doing so, I have deselected my shallow off-board and selected on-board dil as BO gas feeding the BOV. No gasses are open to each other at any time as check valves ensure that; 1. Deep off-board BO can only flow once the on-board dil is either shut down or depleted and 2. O2 can only flow once the shallow off-board BO is either shut down or depleted. Take a close look again at the photos. I hope you can make out that on the upstream port on the O2 side y-block a check valve prevents O2 flowing into the y-block whilst there is pressure present from the shallow off-board BO which is plumbed into the other port and, both off-board hoses have check valves fitted downstream of the male CEJNs. On the dil side, this prevents deep off-board gas flowing whilst on-board dil pressure is present. Otherwise, the check valves prevent water ingress or gas loss I should ever dive without off-board BO or should I disconnect U/W for any reason.
With your off-board plumbed into your dil side first stage, you can certainly shut down your dil cylinder but surely you will continue to expose your off-board gas to the same circumstances which created the boom, i.e. burst HP hose or malfunctioned OPV unless you can disconnect. My system is similarly exposed and I'm going to look into installing an additional check / non-return valve on the dil side y-block to preserve deep off-board BO gas in the case of a boom. Many thanks for this dialogue as its sometimes only when you explain in detail that you realise that deficiencies exist. Peter Wilson / Miflex UK has one in the post for me as I type...
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