Need Math Lesson

Mossyback · 2nd July 2007, 13:53

I'd like to get a larger diluent bottle in the 1.3L to 2.0L range for my IDA-71.

Sizes in North America are in cu. ft. What's the conversion factor or better yet, what would the above two bottles be in cubic feet?

sven · 2nd July 2007, 14:08

Have you tried to Google for "unit conversions"? The first in the list is
Online Conversion - Convert just about anything to anything else

Corallaro · 2nd July 2007, 14:12

probably this can help!

Giovanni

Mossyback · 2nd July 2007, 14:50

Thanks Sven, I didn't think to use Google.

Giovanni, thanks for the chart. It gives me exactly what I was looking for.

Hank

bormes · 2nd July 2007, 16:53

http://www.gopani.com/appendix.html

Yankee Rebel · 3rd July 2007, 07:45

hey Hank!!

theres a free program out there that i found awhile back, and i really like it alot. i forget where i found it originally but it can be downloaded here:
http://www.maxmekker.com/download/GMP230.zip

its called Gas Management Program and for the cylinder conversion portion of it, as long as you know the Cubic Foot and fill pressure of it, you can easily determine the Liters equivalent and the Liters of Gas inside when filled. one thing i really like about it is i can take and figure that an Alum13 with a working pressure of 3000psi is a 1.8 liter cylinder with 368 liters of gas inside at full pressure. the best part since i lack a booster is i can now figure that 1.8 liter cylinder filled to 150Bar (2175PSI, standard K bottle fill pressure from the gas supplier) because i dont have a booster will actually give me 270 liters of O2 in that bottle. makes my life ALOT easier.

ETA the second time...after looking on google for a second.. i realized that i originally got the GMP program HERE from RBW! here is the relevant thread, and it was posted by Maxmekker.
http://www.rebreatherworld.com/decompression-gas-choices/2974-gas-mixing-software-2.html

hope this is of some help to you. if that link does NOT work.. Google GMP230.ZIP and youll find a good link to download from.

Yankee Rebel

ETA:
for a good basic conversion program to convert more day to day non diving stuff.. basic units of weight and measure as well as others, wich can of course be used for diving.. my favorite is this one:
Convert @ joshmadison.com
its free.. and worth the download.

**Dave Sutton** · 3rd July 2007, 18:01

Liters referrs to INTERNAL WATER VOLUME of the cylinder and the volume of the gas contained can vary according to the design fill pressure. A 2 liter bottle filled to 200 BAR contains 400 liters of gas. Pushed to 300 BAR it would have 600 liters of gas. You can see why we *really* like metric system for this.

In the USA, cylinders have been rated for their *free gas capacity* once their fill pressure is vented to the atmosphere. This makes it impossible to determine what tank is "larger" unless you know the fill pressure.

Here's a brain teaser: What US cylinder has a larger ingternal volume, a steel 72 or an aluminum 80? The 80is larger *externally*, but what about the internal volume?

Turns out that the steel 72 has a larger internal volume, as the walls are thinner. For any given PSI it contains more gas. The actual math is that a 72 contains 0.028 cubic feet per PSI (71.2 / 2475 PSI), while an aluminum 80 only contains 0.026 cubic feet per PSI (80 / 3000).

So.... test time:

(1): How many liters are each of the two cylinders (internal water volume)

(2): How many liters of gas does each contain at 150 BAR?

(3): How many at 200 BAR?

(4): What PSI's are expressed by 150 and 200 BAR?

Figure this out and you'll see why we still like steel 72's whan our cpompressors struggle to fill to 3000 PSI but are happy at 2200....

I *hate* imperial measurements....

Dave

Underwaterbear · 3rd July 2007, 18:42

Quote: (Originally Posted by Mossyback)

I'd like to get a larger diluent bottle in the 1.3L to 2.0L range for my IDA-71.

Sizes in North America are in cu. ft. What's the conversion factor or better yet, what would the above two bottles be in cubic feet?

You guys are great...you've given him everything except the answer!

1 cf contains 28.3 L

so assuming your tanks working pressure is 232 Bar your tanks will have
1.3 x 232 = 301 L now divide by 28.3 = 10.7 cf tank. By the same formula the 2.0 L tank is a 16.4 cf tank.

As Dave said you can not change the water capacity of a tank but you CAN change the pressure you fill it to, hence the reason why the old steel 72's are such a great tank. They are roughly a 12 L tank but thats at a WP of 170ish Bar...jam that sucker to 230 Bar and you have 100 cf of gas in a really neat package...nice!

Cheers
AB

Stephane · 3rd July 2007, 18:47

Quote: (Originally Posted by Dave Sutton)

... A 2 liter bottle filled to 200 BAR contains 4000 liters of gas. Pushed to 300 BAR it would have 6000 liters of gas. You can see why we *really* like metric system for this.

Pssttttttt, Dave, you really need to buy a simple $5 calculator: 2x200=400 not 4000.

Mossyback · 3rd July 2007, 19:24

Dave, I agree with you, when it comes to imperial stuff things really get out of hand. It's even worse when you live out in the country and your neighbours still talk in rods and acres.

Thanks for the explanation. The local dive shop would like me to junk my old 72's and replace them with 80 cu ft aluminiums. After hearing from all of you, I think I'll just keep using them.

By the way, Dave, do I have to write the test and will it count towards graduation?

Thanks for the sources, Yankee Rebel. I'll get lots of use out of them.

AB - your conversion examples make sense.

Now all I have to do is find a source for a couple of bottles for my IDA-71 that will come close to fitting inside.

Hank

2nd July 2007, 13:53	#1 (permalink)
Mossyback Custom Title Allowed! Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Mar 2007 Location: Southern Ontario, Canada Posts: 109	Need Math Lesson I'd like to get a larger diluent bottle in the 1.3L to 2.0L range for my IDA-71. Sizes in North America are in cu. ft. What's the conversion factor or better yet, what would the above two bottles be in cubic feet? __________________ "Be the kind of person your dog thinks you are."
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2nd July 2007, 14:08	#2 (permalink)
sven Blogs Admin / Forum Mod Current Rebreather/s: Inspiration Classic Other Rebreather/s: Evolution Join Date: Nov 2005 Location: Sydney Posts: 551	Re: Need Math Lesson Have you tried to Google for "unit conversions"? The first in the list is Online Conversion - Convert just about anything to anything else __________________ Regards, Sven The Sydney Project website: http://www.sydneyproject.com My Blog: http://sven.rebreatherworld.com "Whenever you find yourself on the side of the majority, it's time to pause and reflect." Mark Twain
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2nd July 2007, 14:50	#4 (permalink)
Mossyback Custom Title Allowed! Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Mar 2007 Location: Southern Ontario, Canada Posts: 109	Re: Need Math Lesson Thanks Sven, I didn't think to use Google. Giovanni, thanks for the chart. It gives me exactly what I was looking for. Hank __________________ "Be the kind of person your dog thinks you are."
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2nd July 2007, 16:53	#5 (permalink)
bormes New Member Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Aug 2006 Location: germany Posts: 7	Re: Need Math Lesson http://www.gopani.com/appendix.html
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3rd July 2007, 07:45	#6 (permalink)
Yankee Rebel Custom Title Allowed! Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: Jan 2006 Location: California Posts: 147	Re: Need Math Lesson hey Hank!! theres a free program out there that i found awhile back, and i really like it alot. i forget where i found it originally but it can be downloaded here: http://www.maxmekker.com/download/GMP230.zip its called Gas Management Program and for the cylinder conversion portion of it, as long as you know the Cubic Foot and fill pressure of it, you can easily determine the Liters equivalent and the Liters of Gas inside when filled. one thing i really like about it is i can take and figure that an Alum13 with a working pressure of 3000psi is a 1.8 liter cylinder with 368 liters of gas inside at full pressure. the best part since i lack a booster is i can now figure that 1.8 liter cylinder filled to 150Bar (2175PSI, standard K bottle fill pressure from the gas supplier) because i dont have a booster will actually give me 270 liters of O2 in that bottle. makes my life ALOT easier. ETA the second time...after looking on google for a second.. i realized that i originally got the GMP program HERE from RBW! here is the relevant thread, and it was posted by Maxmekker. http://www.rebreatherworld.com/decompression-gas-choices/2974-gas-mixing-software-2.html hope this is of some help to you. if that link does NOT work.. Google GMP230.ZIP and youll find a good link to download from. Yankee Rebel ETA: for a good basic conversion program to convert more day to day non diving stuff.. basic units of weight and measure as well as others, wich can of course be used for diving.. my favorite is this one: Convert @ joshmadison.com its free.. and worth the download. Last edited by Yankee Rebel : 3rd July 2007 at 07:54. Reason: second link for Convert/Source of GMP230
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3rd July 2007, 18:01	#7 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: Need Math Lesson Liters referrs to INTERNAL WATER VOLUME of the cylinder and the volume of the gas contained can vary according to the design fill pressure. A 2 liter bottle filled to 200 BAR contains 400 liters of gas. Pushed to 300 BAR it would have 600 liters of gas. You can see why we really like metric system for this. In the USA, cylinders have been rated for their free gas capacity once their fill pressure is vented to the atmosphere. This makes it impossible to determine what tank is "larger" unless you know the fill pressure. Here's a brain teaser: What US cylinder has a larger ingternal volume, a steel 72 or an aluminum 80? The 80is larger externally, but what about the internal volume? Turns out that the steel 72 has a larger internal volume, as the walls are thinner. For any given PSI it contains more gas. The actual math is that a 72 contains 0.028 cubic feet per PSI (71.2 / 2475 PSI), while an aluminum 80 only contains 0.026 cubic feet per PSI (80 / 3000). So.... test time: (1): How many liters are each of the two cylinders (internal water volume) (2): How many liters of gas does each contain at 150 BAR? (3): How many at 200 BAR? (4): What PSI's are expressed by 150 and 200 BAR? Figure this out and you'll see why we still like steel 72's whan our cpompressors struggle to fill to 3000 PSI but are happy at 2200.... I hate imperial measurements.... Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 3rd July 2007 at 20:00.
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3rd July 2007, 18:42	#8 (permalink)
Underwaterbear A Prismer in Megland Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2005 Location: Seattle, WA Posts: 198	Re: Need Math Lesson Quote: (Originally Posted by Mossyback) I'd like to get a larger diluent bottle in the 1.3L to 2.0L range for my IDA-71. Sizes in North America are in cu. ft. What's the conversion factor or better yet, what would the above two bottles be in cubic feet? You guys are great...you've given him everything except the answer! 1 cf contains 28.3 L so assuming your tanks working pressure is 232 Bar your tanks will have 1.3 x 232 = 301 L now divide by 28.3 = 10.7 cf tank. By the same formula the 2.0 L tank is a 16.4 cf tank. As Dave said you can not change the water capacity of a tank but you CAN change the pressure you fill it to, hence the reason why the old steel 72's are such a great tank. They are roughly a 12 L tank but thats at a WP of 170ish Bar...jam that sucker to 230 Bar and you have 100 cf of gas in a really neat package...nice! Cheers AB
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3rd July 2007, 18:47	#9 (permalink)
Stephane Stéphane Acounis Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Nantes - France Posts: 788	Re: Need Math Lesson Quote: (Originally Posted by Dave Sutton) ... A 2 liter bottle filled to 200 BAR contains 4000 liters of gas. Pushed to 300 BAR it would have 6000 liters of gas. You can see why we really like metric system for this. Pssttttttt, Dave, you really need to buy a simple $5 calculator: 2x200=400 not 4000. __________________ Stéphane
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3rd July 2007, 19:24	#10 (permalink)
Mossyback Custom Title Allowed! Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Mar 2007 Location: Southern Ontario, Canada Posts: 109	Re: Need Math Lesson Dave, I agree with you, when it comes to imperial stuff things really get out of hand. It's even worse when you live out in the country and your neighbours still talk in rods and acres. Thanks for the explanation. The local dive shop would like me to junk my old 72's and replace them with 80 cu ft aluminiums. After hearing from all of you, I think I'll just keep using them. By the way, Dave, do I have to write the test and will it count towards graduation? Thanks for the sources, Yankee Rebel. I'll get lots of use out of them. AB - your conversion examples make sense. Now all I have to do is find a source for a couple of bottles for my IDA-71 that will come close to fitting inside. Hank __________________ "Be the kind of person your dog thinks you are."
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