Drager Panorama/Golem BOV bailout scenarios

Drmike

As I have experienced an inability (or signficant difficulty) in connecting QCs at time (for the reasons given)

my only advice to you is to go through your switching scenario and assume you cant hold your breath long enough to connect your QC.


By using a BOV your adding more failure points (the bov each QC and its hose), more complexity and more risk but the upside is your likely to have higher wob...no wait thats not a pro...whats the pro again??

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Drmike

I use same one so I know for a fact it can roll shut/open

now try finding it when carrying 4 stage tanks a video camera and a HID light head clipped off - with the deafening sound of a 2 regs freeflowing (cos you have them off same supply) due to hp seat leak and knowledge your losing all your bail gas fast!.....still fast and easy?

well I did about 20 dives with it there and found a) it got rolled a lot, and b) it was much much harder and slower to find than having it under my ear

wow how does that work?! of course it does you are measuring the static pressure. Pressure loss is a function of flow and gas density. You have to consider the pressure drop at the kind of RMV and depth your likley to see

Pool depths wont tell you squat. You need dense gas and high RMV

I find it funny that you find adding one QC more dangerous than relying on many qcs to breathe! IMHO your method is very dangerous indeed. 10 secs can feel like a lifetime when you cant breathe. feels easy sat at a desk or in a pool but at depth with stress - uhuh. Fumble that connection for whatever reason and you could be on a way to a panic CF


what if you cant plug it in?

thats my point.

well lets put it this way. I used to have my FFM rigged just like yours (which is why i can tell you this) I almost drowned because I was unable to connect the QC in time. I learnt the hard way what works. Maybe you will have more luck.

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mempilot

If I can hold my breath long enough to deploy a second stage during a non-BOV bailout, I can hold my breath long enough to work with a QC.

There is only one QC coupling. A single failure point, and signicantly safer than messing with the p-ports for multiple gas switches for each dive IMO.

Higher WOB??? Please explain this. There is no increase in WOB. Pressure is pressure Mike. If I were drawing 120 at the 2nd with 140 at the 1st, I'd agree. That is just not the case. The QC bore is the same as the hose bore. There is no restriction. Maybe there was with gear you have choose to use in the past, but I've actually checked this with my gear selection.

A BOV has pluses and minuses. You see the negative outweighing the benefit of the positive. I see the opposite. While the nasal reg is acceptable during non-stress events for me, it is not during stressfull events. I have a deviated septum. I breathe much better through my mouth than my nose. That being said, the nasal is good for a breath here and there, but I wouldn't want to do it for very long. Irritate your sinuses on a long dive, and your nasal BO isn't going to work. Now, you have to unport and report. I do nothing different. We could go at this all day.

I like the nasal reg for a breath here and there, positive pressure in the mask, and immediate short-term bail out. I like the BOV for long term bail out. I could do without the nasal, but not the BOV in my case. Adding the nasal BO was an easy and cheap addition that gives additional options.

I respect your descisions to stay away from the BOV. My considerations are different from yours.

There's really not any more to hash out.

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Drmike

doesnt that depend entirely on how long it takes to connect the QC? or if at all?

not true. You do not have single point failure you have a QC on every bail tank so thats X no, of QCs and Hoses any of those could fail. Single point is on the bov qc and thats what makes it dangerous. If you cant connect in time you will have to come off ffm,
is your QC valved? if so then its going to have a pressure loss. If not then your bov gonna breathe like a dog cos its gonna get full of water every time you disconnect. See previous post on pressure drop V flow and gas density. Every elbow, swivel, y manifold, shut off etc will add a pressure drop (restrict flow). In addition I havent found a BOV that has as good a wob as normal 2nd stage yet, maybe Ive been unlucky with the few Ive used.


ADDED: perhaps I should explain terminology. When I say pressure loss - each component has a pressure loss, even the hoses. That pressure loss is only felt when theres flow (dynamic) so you will only see it when breathing. You can end up maintaining pressure (pressure is the same) but the flow rate is reduced (due to the restrictions/pressure losses) its all inter-related


So dont use the side reg for bail - I dont. I use it to breathe in the (real) 10 seconds that it takes me to plug in my p-ported 2nd stage.

If you see the p-port no different to your lips then its simple. Oc divers dont generally use switchblock or QC to change regs....why should we? Its really no different at all

Bottom line is seperately both me and Matt have experienced difficulties in fast connection of QCs so just suggest that you consider this when determining your bail out methodology

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mempilot

First, it doesn't roll on and off, it slides. There is a big difference between rolling and sliding off. I wouldn't use a shutoff that can roll off. As for sliding off. BS. Otherwise, you need to replace yours. It's worn out.

Good reason for you to ignore my thread. A typical dive for us down here doesn't require 4 stages. 1 or 2 works all our depths. I configuring for my dives, not yours.

Why would 2 regs free flow? Aren't I breathing off one? I have a single shut off to deal with this unlikely event. BTW, you could have 2 free flows too, but yours would bleed down two gas sources by your claims above.

I've been diving with a shut off on my ADV and all stage 2nd stages for more than your 20 dives and never had one turn off. That is either silliness or you have one really f'd up shutoff. You may want to consider replacing it with a new one.

Dynamic pressure comes from breathing through the reg. That is a function of the 2nd. The first is supplying expected static pressure all the way through what you are calling restrictions. They aren't restrictions, and therefore dynamic pressure should be as expected without the QC or shutoff. ISC uses this same shutoff on the ADV, and it gives one hell of a lot of gas off a LP hose. There is no difference on the LP reg hose I'm talking about.

OK. Checking that tomorrow. But, since static pressure wasn't affected at 1 ATA, I doubt it will be affected other than expected through the 2nd at depth. Again, there is no restriction.

??? Not understanding you here. Explain the bolded statement. I don't find breathing through one QC to be dangerous at all. Mike, if you can't deal with 10 seconds without gas, you shouldn't be technical diving. Go back to deco procedures 101 and practice you skills. Actually, go back to Open Water and practice a lost reg skill. Please don't sensationalize this to try and make your point. It sounds rediculous. If I'm that stressed during a deco gas change, I'll wait until I'm stable before making the switch, or I'll stay on the current gas to shallower depths and let the VR3 recalc deco until I can make a switch to a higher PO2.

Switch to standard OC. ??? What if you can't plug in your p-ported reg? What if your p-port o-ring dislodges during plug in? What happens if it tears? What happens if it isn't on there to begin with because you missed it during predive? What happens if it gets damaged in a wreck or cave? Come on. There are always what if's. You actually have more than I do.

There are very few times where it is neccessary to complete a dive on OC bailout. A complete flood or caustic cocktail being the two big ones. Most other events can be remedied the loop can be returned to if just for a few breaths. In the event of a caustic, I'm getting off the FFM anyway. Chances are, the DSV/BOV are contaminated and I don't want it anywhere near my oral/nasal. All other events, the loop can be flushed and unit either returned to CCR or SCR. On my dives, the only gas changes are going to happen relatively shallow. I carry a deep BO mix equal to my DIL. My intermediate deco gas is usually ean50 with O2 being the finishing gas. I'm in no hurry to get on either of these gasses, because offgassing is happening even on my deep bailout. The only exception to this is when diving the few wrecks we have past 200fsw.

I don't see why bailing to a stand 2nd stage that I carry as backup is all of a sudden a death defying event, making a troublesome QC such a hazzard?? There is still one breath left in the line while the QC is disconnected. The mask comes off pretty quick. The reg comes out pretty quick as well.

In my opinion, this is still simpler and safer than adding p-port adapter to all regs and using a mouthbite condom setup.

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Drmike

of course it slides i used the term rolls beause in diving we talk about 'rolling off' tank valves when they rub against things. In the same way a sliding shut off valve is easy to slide shut/open by rubbing (in my case rubbing against my stage tank) Do I detect your starting to be rude? Just sharing my experiences and trying to help make sure you have a safe bail out method. you did invite crituque by putting details up no?


ah, I was right, turning rude, 'silliness' now is it? OK Ignoring the tone, so you havent experienced sliding of shut off valve so it cant happen and me and matt have experienced difficulty on qc reconnection so...that also cant happen - got it. all of 20 dives huh? wow. Ive been using the shut off valve since my 1st Rebreather dive- so what? still doesnt change that it CAN slide shut.

This isnt about personal experience - (or at least it shouldnt be) its about what COULD happen.

Do you believe a QC can never be difficult to connect? (then you must beliebe I and Matt are a) insane, or b) liars

Do you believe a shut off valve could never be slid shut by rubbing? (then you must believe that I am a) insane or b) a liar.

Look before you turn what was a ok thread into something silly and snipping;

My position is you should consider all possibilities and experiences, you should (if your going to put pics of your rig on the net and invite crituque, be open to that critique) - seams to me your only considering YOUR experiences and not availing yourself of others. Well thats ok its your choice - just dont get all upity and rude cos itll just piss me off. Ive just tried to share and help



No thats not the way it works. The 1st stage outlet pressure (and therefore flow) is regulated yes - but the flow at the 2nd stage depends on the losses between the 1st stage outlet and the 2nd stage. Total flow depends all all losses incl 1st stage valve. Any change in dia, every bend every step and fitting is a pressure loss (which will relate a flow restriction for constant pressure). Im sorry thats physics. Please dont get mad at me.


ADDED: By way of an example, try breathing out naturaly through a small straw (high loss) then compare to breathing out naturally through a bigger straw (low loss) which straw will take the longest to breathe out of? ie which has the biggest flow restriction (losses) ?
The average pressure in both straws are the same yet the flow rates are different



if theres no restriction then its a valve less QC.....which I doubt as you would be flooding your stages everytime.... The available flow rate into your lungs is whats critical. That flow rate is a function of the losses in the system and the pressure set at 1st stage. Increase losses (through fittings, gas density etc) and you will see less flow for const P. So depth, gas choice and fittings will all effect. We all have regs that seam to beathe great at surface but dogs at depth with high rmv and gas density. You will see that CE ratings for regs specify wob at 40m, this is because the deeper you go (increased gas density) the higher the losses and the higher the wob will be - so yes depth is important (which is why i said a pool test wont tell you much)
I think your starting to sound a bit childish here and frankly starting to get on my tits. Ive ONLY made the point (as has others) that QCs can stick and can be hard/impossible to reconnect. I have made the point that when stressed and unable to breathe 10 secs can feel like a lifetime underwater and I have shared with you my experience that I had a mare when I had my kit configured just as yours is and my QC failed in just the way Im describing.

But you dont want to hear that and start calling me a sensationalist well fine - just trying to offer you some advice seeing as Id tried it your way and it sucked. If you dont want to hear peoples critique and experiences dont put pics and discriptions of your set up up on the net and invite them!!

I guess Im an asshole now because I didnt say how lovely your set up was and how cool you are and clever at making it. Guess Im the assholle now for simply trying to warn you about my experiences with the exact same set up!

Nice

ok silly time over. Im an ass - got it. i wont be posting anymore in this thread so feel free to confrm im an ass then you can move on.

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Lancer4545

Hey Eric,

Good to see you have been thinking through different scenarios and working out your system to deal with them.

Looking at your gas routing I have to say I agree with Mike that having both supplies to your "Sanity Breathing Regs" coming from a single gas source and isolated with a single flow stop on the the supply is not a good choice. If you loose gas or have a free flow to one you loose it to both.....Not an ideal situation.

I think it's a wiser decission to have a flow stop on each second stage (Nasal and BOV) that way when you jump in and the BOV free flows, as it usually does, you can now have it isolated and still have the ability to add loop volume with the nasal reg and not have your gas venting and loosing IP (if youre at depth) If you decide to isolate the gas to them then you are also isolating the nasal reg and loosing the pressure to the mask facial cavity....so now it might as well not be there. I isolate my ADV all the time and really only use it when I am doing a cell check or loop flush. Adding loop volume is done by breathing in through the nose and out through the mouth into the loop. When you get used to it, it's great and no where near as hard as getting the ADV to fire.

Another consideration is, when gas changing whilst bailed out, you only have 1 gas source....disconnect the QD you now have none. With the manifold you still have gas from your dil tank. So you can fumble around a bit and it isn't going to drown you.........

The BOV and Nasal second stage being supplied from the stage tank is going to drive you nuts when you find you will have to fill both tanks instead of just your Dil tank. With a manifold it runs the dil tank down before accessing your stage tank ( I have my IP's set so the Dil tank is slightly higher than the stage) I have the stage tank on all the time and if I were to run out of dil it will automatically access the stage tank but not until the Dil tank is empty. If I want it to acess the stage tank and not the Dil all I need to is turn the Dil tank off.......Nothing could be easier!!

Both hoses running from the right will also drive you nuts....I tried both mine on the left and it sucked big time!!! I changed it back as soon as I returned home and put it down to experience!!

My thinking behind the BOV is that in the event I have to bail to OC I have a really nice Apeks second stage built into the BOV and there is nothing easier than twisting the knob on the front. Having to remove and replace P'Ports is a real nuisence.........and is not an easy task when you're stressed and cold and not thinking as clearly as you'd like.

If it all turns bad and you have to remove the FFM for whatever reason and bailout, the stage tank second stages are there ready with a nice bite mouthpiece. A stretched mouthpiece over a P'Port might do for a little while but it's not a good option and will drive you nuts.

If you have to isolate the manifold ......... disconnect the QD.

If you loose the onboard dil and the manifold system. Disconnect the QD and fit the DIN hose to the MGB or wing........

The manifold with access to off board gas has many more options available and is safe and simple.........

Have fun diving tomorrow and don't forget to keep your hair out of the mask seal

Regards,

Lance

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jkaterenchuk

Mike, Eric, Lance and Matt

I learned alot during this discussion. Thanks all for sharing. Hearing different opinions and reasons is great. One of the most informative threads in a while on a topic that I have no knowledge and experience.

Even if the exchange go a little heated recently if still worked for me.

John

mempilot

Mike,

Not trying to be rude. Sorry if it came across that way. Debate is good. It is how we test our theory and convictions. I'm actually considering parts of your argument, like having the BOV and nasal reg run from seperate sources. I will; however, keep the BOV and nasal reg as I see benefit in both.

Again, I like good debate, just as you do. It makes me think a little harder when trying to prove I'm right. The term 'silly' may have different meaning, so probably not the best word to use. Sorry for that.

Lance,

My buddies with Golem BOV's told me right up front about the free flow issue when jumping in. When I test dived it the other day, it was shutoff prior to splashing and turned on when I hit the bottom. I was trying to keep to that procedure with both bailout sources now, but I can see Mike's and your point about same source. I'll dive it this way today, and work on modifying it tomorrow. As far as the manifold, it may come to that. I was trying to keep it as simple as possible, but I see your path to ending up there. .

Mouthbites stretched over p-ports is not for me, and I wouldn't do it to my buddy. I find it very uncomfortable, easy to pop off, and therefore not a good solution for me. I will respect others whom decide to do so, but there has to be a better way.


-----


Guys,

I really do thank you for your input. Sometimes we have to work it all through ourselves and end up in the same place in the end. I truly believe that this is how you become intimate with your decisions versus just copying and not understanding. In the end, if you heed advice and really think things through, you become a better and more knowledgeable diver.

Again, I'm sorry if I offended you Mike. You know I always enjoy a good debate with you, even though you are always right!

Time to go out to the dive locker and start the final assembly.

Dive safe!

Eric

__________________
MEM "Da Pilot"

Black holes are where God divided by zero.

"If at first you don't succeed, don't dive silent."

"Would you mind not shooting at the thermo-nuclear weapons." ~ Vic Deakins

"Donkey's kill more people annually than plane crashes."

Drmike

you know it would save so much time if people just accepted that fact


No worries

cheers
m

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