SPGs on CCRs

[doctormike]

Several people report that feel safe with no pressure guage on their rig at all. If you don't have a pressure guage attached to your rig All_The_Time, then you are not going to check it before every dive.

I have found my O2 bottle bone dry more than one time when setting up for a dive. I didn't turn if off after the previous dive (constant flow MCCR) or it got jostled, or something just went wrong. You may not be aware of what your pressure was at the end of the day's diving (10 hours after all, good for a few days!) and misjudge your starting pressure the next morning.

I don't check my guages in the water most of the time, as I check it before the dive. But if I am on the third dive of the day and starting with under 1000 PSI in the tank you bet I check it half way though the dive.

It should be obvious that you are putting yourself and everyone around you at risk with such complacency. Is there a single CCR manufacturer that suggests running without guages?

I can't speak for everybody, and I do have SPGs that I check during my dive. Maybe I misinterpreted what you were saying. But I'm assuming that if you dive a rig with no pressure gauge on it, that obligates you to check pressure before you dive somehow. Perhaps @JohnnyC or @Superlyte27 can chime in here on this point, since I have no experience with that configuration.

 

[doctormike]

I don't think that was his real point. It seems to me that his point boils down to this: If you check your cylinder pressure, mount your cylinders on your CCR immediately, then go through all your checklists and, essentially, get in the water more or less right away, you could be okay with no pressure gauge.

You are reading past the data...

 

[JohnnyC]

The idea that without an SPG that pressure wouldn’t get checked every dive is absolutely inaccurate. I’m sure there is someone, somewhere that doesn’t, but the plural of anecdote isn’t data.

I check my bottles for pressure when filled and analyzed, when analyzed during the build, and when doing another pre-dive pos and neg at the dive site. It’s part of the checklist I follow EVERY.SINGLE.DIVE. I absolutely know my pressure before getting in the water, which is really all I need to know.

 

[rddvet]

All I can say is that you need to be aware of other points of view than your instructors. What you relayed is the sort of arrogant macho BS that gives tecdivers a bad name.

Seriously, this is just bad logic. Just because you have O2 flowing now and your PO2 is good now, does not mean you have more than 100 PSI in the tank. If you jump off the boat without complete awareness of your gas supply then you may end up with "a bigger problem."

Call it arrogant and macho if you want but it’s my perspective. You’re assuming my instructor didn’t discuss the pros and cons and that’s not correct. You can see it as bad logic as you like, but I disagree. There’s nothing wrong with being overly cautious by having spgs. I was once in that camp. Now I’m not.

 

[rddvet]

Several people report that feel safe with no pressure guage on their rig at all. If you don't have a pressure guage attached to your rig All_The_Time, then you are not going to check it before every dive.

I have found my O2 bottle bone dry more than one time when setting up for a dive. I didn't turn if off after the previous dive (constant flow MCCR) or it got jostled, or something just went wrong. You may not be aware of what your pressure was at the end of the day's diving (10 hours after all, good for a few days!) and misjudge your starting pressure the next morning.

I don't check my guages in the water most of the time, as I check it before the dive. But if I am on the third dive of the day and starting with under 1000 PSI in the tank you bet I check it half way though the dive.

It should be obvious that you are putting yourself and everyone around you at risk with such complacency. Is there a single CCR manufacturer that suggests running without guages?

Missed this earlier. You’re assuming that between dives people don’t check their pressures. That’s you assuming. Because I don’t have spgs I check before every dive even if it’s just two short dives.

And yes, the manufacturer of my unit sells them without spgs.

 

[Superlyte27]

Several people report that feel safe with no pressure guage on their rig at all. If you don't have a pressure guage attached to your rig All_The_Time, then you are not going to check it before every dive.

I have found my O2 bottle bone dry more than one time when setting up for a dive. I didn't turn if off after the previous dive (constant flow MCCR) or it got jostled, or something just went wrong. You may not be aware of what your pressure was at the end of the day's diving (10 hours after all, good for a few days!) and misjudge your starting pressure the next morning.

I don't check my guages in the water most of the time, as I check it before the dive. But if I am on the third dive of the day and starting with under 1000 PSI in the tank you bet I check it half way though the dive.

It should be obvious that you are putting yourself and everyone around you at risk with such complacency. Is there a single CCR manufacturer that suggests running without guages?

I'd be willing to bet that I have more hours on CCR than you do (I'm certified on 5 units and I have nearly 1000 hours just on my latest unit). I have NEVER, not once, ran out of oxygen on a dive. I keep a pressure gauge right next to build kit. But, let's say I did run out of oxygen, the least amount of bailout I carry is 144cu' of gas. I can run SCR for quite a while that way.

When teaching, I wear gauges to meet standards, but after the first 100 hours on CCR, I quickly realized it was a waste of space.

 

[davehicks]

The idea that without an SPG that pressure wouldn’t get checked every dive is absolutely inaccurate. I’m sure there is someone, somewhere that doesn’t, but the plural of anecdote isn’t data.

I check my bottles for pressure when filled and analyzed, when analyzed during the build, and when doing another pre-dive pos and neg at the dive site. It’s part of the checklist I follow EVERY.SINGLE.DIVE. I absolutely know my pressure before getting in the water, which is really all I need to know.

So you take off the bottle before every dive, add an SPG so you can measure between dives, remove the SPG again, and reconnect the bottle to your unit. Every dive.

Yeah this sound a lot more convenient and sustainable than simply mounting an SPG on your unit.

Sorry, I don't see the benefit and would not believe that this excessive complexity would be followed 100% of the time.

 

[JohnnyC]

So you take off the bottle before every dive, add an SPG so you can measure between dives, remove the SPG again, and reconnect the bottle to your unit. Every dive.

Yeah this sound a lot more convenient and sustainable than simply mounting an SPG on your unit.

Sorry, I don't see the benefit and would not believe that this excessive complexity would be followed 100% of the time.

No, it’s a pressure checker that takes all of 10 seconds to use.

I don’t care if you believe it or not. Just because you’re complacent doesn’t mean the rest of us are. I’m not the one that forgets to turn off his O2 on his mCCR on what sounds like a fairly regular basis. Maybe you should be reevaluating your rebreather habits, since you’re the one that seems to have issues with complacency.

 

[Superlyte27]

I dove mccr for 4 years. I never turned the gas off from the start of my day to the end of my day. I didn't want to forget to turn it on pre-jump.

If I have 3l filled to 200 bar and my needle valve leaks at .8l/min, how long til that bottle is empty? A long friggin time. Oh, and I don't pay for oxygen. That tank will last all day.

 

[rddvet]

So you take off the bottle before every dive, add an SPG so you can measure between dives, remove the SPG again, and reconnect the bottle to your unit. Every dive.

Yeah this sound a lot more convenient and sustainable than simply mounting an SPG on your unit.

Sorry, I don't see the benefit and would not believe that this excessive complexity would be followed 100% of the time.

I don't know how other people do it, but it's a simple 30 seconds. My valves are up line in backmounted doubles. I simply pop off the reg, throw on the pressure checker, then throw the reg back on. 30 seconds and easy as pie. Sure an spg would be faster, but the most common failure I've had is of HP spools. Why do I want to add 2 failure points when I personally feel no need for an spg.

Not sure why you've gotten so spicy about the whole thing. Nobody has said you're wrong for having spgs. Sure it's potentially safer. Those of us in the no spg camp are simply explaining we don't feel it's necessary.