When does the world go metric...

[Blackwood]

...

As I said, I'm not solving a problem. I'm not even pointing one out. I just commented on the apparent logic of one scale versus another.

 

[Footslogger]

Medicine has a love/hate relationship with the metric system. Been in the field since the early 70's and we often still use inches and centimeters (although they tend to pronounce it "contemeters") in the same conversation. It's really kind of amusing at times. Most of the surgical hardware now is specified in metric units but some of the surgeons will say "...give me the 3/16ths bit".

I don't see there being any universal change in the short term.

'Slogger

 

[lamont]

As I said, I'm not solving a problem. I'm not even pointing one out. I just commented on the apparent logic of one scale versus another.

But all these temperature scales are human defined conveniences. If you're trying to arrive at a priori objective logically sound measurements, then the planck measurements probably are the best since they're defined based on characteristics of gravity/space-time and quantum mechanics which are really inherant to the universe and universal as far as we know. Every other temperature scale and units are defined in order to be convenient to human beings. Absolute temperature scales are only relevant to humans who need to know about the energy distribution of the matter they're concerned with. Most people are not and therefore absolute temperature scales make a pretty bad temperature scale for most people. OTOH, if you're trying to figure out how much a hot fill will increase the pressure of your scuba tank you are suddenly in the miniority that cares about absolute temperature.

 

[ianw2]

Here’s a great site for volume conversions:

http://www.lenntech.com/unit-conversion-calculator/volume.htm

80cft = 2264 liters

This is known as a "hard conversion". I have no idea about standard sizes of European tanks, though (a "soft conversion").

BTW, the tank holds 80cft when the pressure is 300psi (give or take). You wouldn’t add in a conversion to pressure to get to 11 liters. A liter is approximately equivalent to a quart which makes it easier for my mind to grasp.

Since we know the standard pressure at the surface, and we know that a tank should hold 80cft of air at 300 PSI, we should be able to calculate the actual internal volume of the tank.

80cft / (3000 psi/15 psi) = 0.4cft or about 11 liters. In other words, if you were to open up the tank and pour in water, it would contain only 0.4 cft of about 11 liters or about 3 gallons.

 

[KOMPRESSOR]

Allow me to rephrase the question in a way that will answer the question I would ask.... if an al80 is the standard tank throughout the US, Canada, and the Caribbean, what would the equivilent tank be in Europe?

Rachel

There isn't one...

I don't know about the south but up here it's all steel. For starters...

Then we've had 200 bar and 300 bar rated (wp) tanks as the main differences, although I don't think anyone in southern Europe uses 300 bar. It's more of a dry suit thing with PADI crash education up north... Less lead on the students & saved time. They will sink...

Then there are generally 3-4 types of single tanks we see around where I dive (Nordics). These are:

1. 15 liter 200 bar
2. 10 liter 300 bar
3. 12 liter 232 bar long
4. 12 liter 232 bar short

To top it off one can occasionally spot larger and heavier tanks as well. But more and more experienced divers are now looking at doubles like 2x12L 232 bar (long).

 

[String]

Common tanks in europe (and most of the rest of the world) for standard recreational diving by far the most popular is the 232 bar 12 litre tank.

10ls are also used (also 232 bar) as are 15 litres (232 bar...).

A pony is generally 3l whereas deco stages are often 5 or 7l (again all filled to 232 bar).

* 232 bar is roughly 3410 psi

If from above an 80 cu ft tank contains 2264 litres id go back to the fill station and demand a top up as thats only 205 bar out of the expected 232!. Doing some maths a standard american 80 cubic foot tank filled to 3000 psi gives 2200 litres of air. The nearest rest-of-world equivalent 12l/232bar tank gives 2784 litres so roughly 20% more air.

Generally only very old tanks (usually aluminium) tend to be 210 bar fill pressure (3087 psi). Vast majority of tanks are steel 232 bars. 300 bar (4410 psi) tanks are around but theyre very heavy and due to gas laws breaking down doesnt mean you get 68 bar more air than a standard tank either. These tanks are far less common.

But basically go into a dive centre in most places in europe and the rest of the world and you're very likely to get a 12 litre 232 bar tank.

 

[terrasmak]

Depends on the type of engineering, alot of it is done in metric. The major exception would be anything dealing with architects... that's all still done in imperial.

Everything else that's still done in imperial in the US (Shoe sizes, miles, gallons of milk, gallons of gas, etc) is nothing that really effects anyone anywhere, it's just tradition.

Then you have the other stuff like a 2 liter of cola , most USDM cars dave there displacement listed in liters now too.

 

[Packhorse]

80cft / (3000 psi/15 psi) , if you were to open up the tank and pour in water, it would contain only 0.4 cft of about 11 liters or about 3 gallons.

This is how we rate tank sizes here. 12kg WC or Water Content= 12Kg's of water and 12Kgs of water displaces 12litres.

 

[plot]

Then you have the other stuff like a 2 liter of cola , most USDM cars dave there displacement listed in liters now too.

Yup. It's a healthy mix.

 

[ianw2]

This is how we rate tank sizes here. 12kg WC or Water Content= 12Kg's of water and 12Kgs of water displaces 12litres.

That's what I was just figuring out. You rate your tanks in empty volume and give a pressure rating.

With our tanks, we label them as the volume of air they will hold at the rated pressure. For example: an 80AL is an aluminum tank that will be under 3000 PSI when 80 cft of air are pumped into it. A steel 80 will actually be smaller in internal volume because the tank can be presurised to a much high level. The numbers are actually rounded off a bit, but that's the concept at least.

Cheers, mate!