Mini pressure guages ?

[Tracy]

Huh?

He was mocking the guage, it is a typo. No such thing as a guage.

 

[Mike1967]

He was mocking the guage, it is a typo. No such thing as a guage.

Ahhh I didn't even notice lol

 

[Bigceff]

Yeah, potato potato tomato tomato guage gauge whatever...

 

[Wibble]

Suit inflation bottle only. Never for breathing gas where accuracy is required especially in extremis.

 

[stuartv]

He was mocking the guage, it is a typo. No such thing as a guage.

Thank you! I am normally totally OCD for spelling accuracy. But, I didn't catch that. I was also totally in the dark about what was really going on there. LOL

 

[stuartv]

Suit inflation bottle only. Never for breathing gas where accuracy is required especially in extremis.

Can you give of an example of a specific scenario where you are "in extremis" and the accuracy of your SPG changes what your actions would be?

E.g. you're deep into a wreck penetration, diving on BM doubles. Just at the furthest point, right as you hit your turn pressure, the HP seat in one of your 1st stage regs goes. By the time you get that post shut down, you've lost enough gas that you are well below your turn pressure. The mini SPG on your deco gas says 3000, but the pressure in that cylinder is really 2700. It says 3000. Would you do something differently at that point if it actually said 2700?

 

[Wibble]

Can you give of an example of a specific scenario where you are "in extremis" and the accuracy of your SPG changes what your actions would be?

E.g. you're deep into a wreck penetration, diving on BM doubles. Just at the furthest point, right as you hit your turn pressure, the HP seat in one of your 1st stage regs goes. By the time you get that post shut down, you've lost enough gas that you are well below your turn pressure. The mini SPG on your deco gas says 3000, but the pressure in that cylinder is really 2700. It says 3000. Would you do something differently at that point if it actually said 2700?

Something goes wrong and you need to work out your options. Using your example, if you knew it's 2700 you could make a change to the plan: get the heck out of dodge without passing Go and picking up your jump lines. Or if your deco gas is low (freeflow?) then you may decide to take your chances by reducing your deep stops (e.g. changing your GF-low on the fly) -- i.e. you plan in advance for running "out" of a gas, but mitigate before it's an emergency.

Personally I see the button gauges as a simple gas / no-gas, such as you need to know with your drysuit inflate. For all breathing gasses, a decent gauge is far more preferable than interpreting a very cheap & nasty tiny pointer.

 

[stuartv]

Something goes wrong and you need to work out your options. Using your example, if you knew it's 2700 you could make a change to the plan: get the heck out of dodge without passing Go and picking up your jump lines. Or if your deco gas is low (freeflow?) then you may decide to take your chances by reducing your deep stops (e.g. changing your GF-low on the fly) -- i.e. you plan in advance for running "out" of a gas, but mitigate before it's an emergency.

Personally I see the button gauges as a simple gas / no-gas, such as you need to know with your drysuit inflate. For all breathing gasses, a decent gauge is far more preferable than interpreting a very cheap & nasty tiny pointer.

You're saying you can imagine a specific scenario where, if it was 3000, then you WOULD stop to pick up your jump lines, but you wouldn't if it was 2700?

My thought is, if I lost a gas, the difference between 2700 and 3000 is no difference. I would proceed the exact same way in either case. There is no "I have 300 more psi, so I can stop to take up my jump lines."

 

[Wibble]

You're saying you can imagine a specific scenario where, if it was 3000, then you WOULD stop to pick up your jump lines, but you wouldn't if it was 2700?

My thought is, if I lost a gas, the difference between 2700 and 3000 is no difference. I would proceed the exact same way in either case. There is no "I have 300 more psi, so I can stop to take up my jump lines."

Need to convert to bar: 3000psi = 206bar, 2700psi = 186bar.

Obviously it depends upon circumstances, but in essence yes. It's probably more relevant for a cave penetration rather than a wreck penetration (wrecks aren't as long as caves!) where you've ended up using more than your third of gas and are now eating into your reserves.

For a wreck penetration, you'd have worked out your max TTS (time to surface) and your minimum gas. If your "disaster" (post leak) happens when you're in deep and you realise that you're now getting close to your TTS / min gas, getting out is definitely time critical. That 20bar / 300psi could make all the difference. If it really is a long or complex penetration, you can simply leave the line there and collect it another day; same with a cave for that matter -- much better to have a story on the boat / in the pub than to scare yourself witless with worry because you're now short of gas.

(The example numbers you used would have been better if they were lower, e.g. at the turn point, so call it 1700psi / 117bar and 2000psi / 137bar - here the loss of 300psi / 20 bar is more significant)


Edit: typo 2700 & 3000 swapped

 

[Tracy]

Need to convert to bar: 2700psi = 206bar, 3000psi = 186bar.

I don't consider myself a mathematical genius, but I am fairly certain your calculations are incorrect.