Metric versus Imperial System for Diving?

[redacted]

Impossible. The output pressure of first stage regulators are set anywhere from 110 to 150 psi ABOVE ambient pressure depending on brand. Using 110 psi, at the surface the first stage output is 110 + 15 or 125 psi. If the tank pressure is 125 psi the pressure drop from tank to 1st stage output is 125 - 125 = 0 psi. Zero pressure drop equals no flow and this is at the surface. This means absolute rock bottom tank pressure cannot drop below 125 psi. At depth to maintain flow the tank pressure must be higher.

Did you get that out of the flat earth society physics book? You might want to try breathing a tank down to empty through your regulator and then see what happen when you remove the regulator and open the valve.

 

[EFX]

It'd be so much easier for the dive guide to simply say "tell me when you get to Xbar or Ypsi with the fist-on-chest symbol"

I've never seen the need to know the exact pressure of a fellow diver.

Many DM's do this. You don't need to do any calculations beyond simple math. You need to know that 3000 psi = 200 bar (assuming AL80's). Look at your SPG and read what proportion it is compared to a full tank. If it's a 1/3 estimate it to 60 bar. If it's a 1/4 estimate it to 700 psi. If you are still getting surprised looks have the DM read your SPG (they'll probably swim over and read it anyway).

---------- Post added October 27th, 2014 at 07:16 PM ----------

Did you get that out of the flat earth society physics book? You might want to try breathing a tank down to empty through your regulator and then see what happen when you remove the regulator and open the valve.

No. I think you can deduce the concept from high school science books but for a more rigorous treatment see a textbook on fluid mechanics. I don't need to try it. You're the one who doesn't believe it so give it a try and enlighten us all or at least explain how.

 

[drrich2]

I have no doubt that the US will eventually give in and adopt SI and I hope to be alive when it happens. A few halfhearted attempts have already been made in the past and there's considerable support within the country. It just takes the right sort of government to actually pull through with it.

Doesn't sound like a 'by the people' government.

It may not reflect the average American, but the fact that some people feel that way and aren't even ashamed to admit it is somewhat concerning and sure doesn't help your nation's image abroad (which is what originally led to this discussion).

Because there's nothing there to be ashamed of.

I've heard of occasional protests here and there in other countries complaining about U.S. policy decisions like military intervention, but never a big riotous protest over our use of the imperial system.

Perhaps if we tell them we weigh all our bombs and bullets in kilograms that will make it better...

Richard.

 

[dfx]

The problem here is not the measuring system but the human (communication) system. How are you showing remaining air? Do you sign each digit? If so, there is NO confusion. If signing 7-0-0, it can't be bar -- must be psi. If signing 7-0, it can't be psi -- must be bar.

Yeah. Except that nobody does that.

And what if you signal 1-5-0?

It'd be so much easier for the dive guide to simply say "tell me when you get to Xbar or Ypsi with the fist-on-chest symbol"

Yeah. Except that nobody does that. Well maybe not nobody, but it's more of an exception.

I mean sure, you could lobby for internationally adopting a different system for signalling remaining air/pressure. But since there's no actual recognized standard for that even now, it ain't gonna happen. People do what is easiest.

Or you can lobby against dive guides asking for other people's air/pressure. But you must be forgetting annual cruise ship divers when you do that. Ain't gonna happen.

Much easier is to just get rid of an archaic, obsolete and cumbersome system of measuring things that serves no practical purpose and that nobody uses except one country, especially since the residents of that country seem to pride themselves on also being fluent in another, much better system that everybody else uses.

---------- Post added October 27th, 2014 at 08:28 PM ----------

Doesn't sound like a 'by the people' government.

Yeah it does. Sometimes "the people" just don't know what's best for them.

Because there's nothing there to be ashamed of.

A "we're the best, f@#$ the rest" attitude is not something to be ashamed of?

 

[victorzamora]

A "we're the best, f@#$ the rest" attitude is not something to be ashamed of?

It's funny how the Euro/Metric crowd is the only one with that attitude in this entire thread.

It's also funny how few Americans have that sentiment but how many non-Americans believe all Americans have that sentiment.

 

[EFX]

Yeah. Except that nobody does that.

What do you mean nobody does that?!! You said you witnessed it. Go back to your post and re-read it. I was responding specifically to your example. As far as your 1-5-0 example, so what? It's a problem easily solvable by my point that you and your DM need to COMMUNICATE. Communicating means agreeing on a common system (whatever that system may be) and establishing hand signals.

Much easier is to just get rid of an archaic, obsolete and cumbersome system of measuring things that serves no practical purpose and that nobody uses except one country, ......

One country? Wrong. See Countries That Don?t Use the Metric System

---------- Post added October 27th, 2014 at 08:28 PM ----------

 

[dfx]

Wait. Wasn't your example 7 fingers? Go back to your post and re-read it.

Uhm, yeah, and? 7 fingers can mean either 70 bar or 700 PSI. What's your point?

One country? Wrong. See Countries That Don?t Use the Metric System

Oh yeah. You're in awesome company. Damn, you sure showed me there. And BTW, Burma has since adopted the metric system. Apparently Liberia has too, but it's kinda hard to tell these days.

As to the rest of your points: LOL!

 

[Bob DBF]

One country? Wrong. See Countries That Don?t Use the Metric System

If the USA dosen't use metric, why do I have to own two different sets of tools in my shop? Metric tools are not just for foreign cars any more.


Bob
--------------------------
I may be old, but I'm not dead yet.

 

[drrich2]

A "we're the best, f@#$ the rest" attitude is not something to be ashamed of?

I don't think anybody advocates for the imperial system being better than the metric. It's just what we're already using, and it's good enough, and a lot of us don't want to change, and are getting along fine as is.

As for F the rest, no, we're really not thinking about the rest of the world much in this regard. Not with hateful contempt, but not with a perceived need to imitate them, either. Probably the most applicable cliche' is 'Live and let live.' Nothing to be ashamed of in that.

Richard.

 

[Tigerman]

I don't think anybody advocates for the imperial system being better than the metric. It's just what we're already using, and it's good enough, and a lot of us don't want to change, and are getting along fine as is.

As for F the rest, no, we're really not thinking about the rest of the world much in this regard. Not with hateful contempt, but not with a perceived need to imitate them, either. Probably the most applicable cliche' is 'Live and let live.' Nothing to be ashamed of in that.

Richard.

I cant really say that as a European the choice to use imperial units in the USA provoke me very much or bother me either.
I DON'T however get why people think that imperial is "easier" or that they "cant relate to a meter" as I have no problem knowing what a foot (or three) is, but its quite a way from there to be offended by your choice of units