G size cylinders

opimoby · 6th September 2007, 09:39

I am about to go on the Undersea Explorer out into the Coral Sea diving my new Evo. I am taking a full G size cylinder to decanter into my 2 liter Evo cylinders. I have no booster pump at this time. Does any one know a approx. what the sliding differentail will be as I use up the gas volume in the big G. It starts at 180 Bar but I obviously won't get that in the first fill perhap 160. I am interested to see what sort of milage I will get out of the G.
thanks
Ross

LukeN · 6th September 2007, 10:04

One would think that you should know how to work this out? If you are decanting your own cylinder one would hope you are a gas blender and have some idea about what you are doing

Marky Mark · 6th September 2007, 10:14

Just work out the free volume of gas in each case and hey presto.

Strange what obvious stuff some folk forget...

Lancer4545 · 6th September 2007, 11:43

So you don't believe me!!!

Lance

koputai · 6th September 2007, 11:55

Ross,
Assuming you take the 2L down to 50 bar each time, you should get something like this:
174
169
164
160
155
151
147
143
139
136
132
129
126
122
120
117
114
111
109
106
104
102
100

Cheers,
Jason.

opimoby · 6th September 2007, 12:10

thanks jason

koputai · 6th September 2007, 23:00

No worries.
If you want to work it out with other cylinder sizes/numbers/pressures, here's the spreadsheet.
If you're only using one supply cylinder (bank) just put zero for the pressure in the others.

Cheers,
Jason.

OK, I don't seem to be able to attach an xls file, so here it is on my site:
http://www.deepdiving.net/tools/cascading2.xls

opimoby · 6th September 2007, 23:21

Hey Jason thanks very much for your assistance...some people are really helpfull in these forums others well waste of space.....cheers Ross

bendomatic · 7th September 2007, 03:02

well your question kinda indicates that you haven't got a clue, unless someone else is doing the decanting for you.
rachel

PeteS · 7th September 2007, 03:47

Quote: (Originally Posted by opimoby)

Hey Jason thanks very much for your assistance...some people are really helpfull in these forums others well waste of space.....cheers Ross

Well, your question concerns me, because it is about a very basic thing that is covered in various blenders courses. It suggests a lack of basic knowledge regarding the relationship between pressure and volume.

Being spoon fed answers isn't always the best thing, understanding the subject is.

Sorry to be a waste of space.

How to work it out:-

Get pressure and volume of your cylinder and mutiply them together, this will give the litres of gas in the cylinder.

Do the same for your large cylinder.

Add the two numbers together

Divide that number by the total volume of both cylinders added together, and that will give you the final fill pressure.

So the formula is:-

( ( P of J x Vol of J ) + (P of Dil x Vol of Dil ) ) / (Vol of J + Vol of Dil ) = Fill pressure in Bar

6th September 2007, 09:39	#1 (permalink)
opimoby New Member Current Rebreather/s: Evolution Other Rebreather/s: MK 15.X Join Date: Jul 2007 Location: Port Douglas, Australia Posts: 68	G size cylinders I am about to go on the Undersea Explorer out into the Coral Sea diving my new Evo. I am taking a full G size cylinder to decanter into my 2 liter Evo cylinders. I have no booster pump at this time. Does any one know a approx. what the sliding differentail will be as I use up the gas volume in the big G. It starts at 180 Bar but I obviously won't get that in the first fill perhap 160. I am interested to see what sort of milage I will get out of the G. thanks Ross __________________ If you build it...they will come..
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6th September 2007, 10:04	#2 (permalink)
LukeN New Member Current Rebreather/s: Optima Other Rebreather/s: Not Bought Yet Prism Topaz Join Date: Jun 2005 Location: Australia,West Aus Posts: 79	Re: G size cylinders One would think that you should know how to work this out? If you are decanting your own cylinder one would hope you are a gas blender and have some idea about what you are doing __________________ Luke Nelson www.imagedive.com.au
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6th September 2007, 10:14	#3 (permalink)
Marky Mark New Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Oct 2006 Location: Darlington, UK Posts: 80	Re: G size cylinders Just work out the free volume of gas in each case and hey presto. Strange what obvious stuff some folk forget... __________________ It'd be rude not to. "You are a terrestrial mammal for crying out loud - you have no business going underwater in the first place." - Richard Pyle (and my mum)
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6th September 2007, 11:43	#4 (permalink)
Lancer4545 Closed Circuit Divers Aus Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jun 2007 Location: Cairns QLD Australia Posts: 573	Re: G size cylinders So you don't believe me!!! Lance __________________ You can run but you can't hide! ISC Appointed Megalodon Dealer for East Australia http://www.closedcircuitdivers.com.au info@closedcircuitdivers.com.au
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6th September 2007, 11:55	#5 (permalink)
koputai Subsea Systems Current Rebreather/s: MK 15.X Other CCR Other SCR Other Rebreather/s: Not Bought Yet Other CCR Other SCR Join Date: Jul 2005 Location: Sydney, Australia Posts: 308	Re: G size cylinders Ross, Assuming you take the 2L down to 50 bar each time, you should get something like this: 174 169 164 160 155 151 147 143 139 136 132 129 126 122 120 117 114 111 109 106 104 102 100 Cheers, Jason.
(Online)

6th September 2007, 12:10	#6 (permalink)
opimoby New Member Current Rebreather/s: Evolution Other Rebreather/s: MK 15.X Join Date: Jul 2007 Location: Port Douglas, Australia Posts: 68	Re: G size cylinders thanks jason __________________ If you build it...they will come..
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6th September 2007, 23:00	#7 (permalink)
koputai Subsea Systems Current Rebreather/s: MK 15.X Other CCR Other SCR Other Rebreather/s: Not Bought Yet Other CCR Other SCR Join Date: Jul 2005 Location: Sydney, Australia Posts: 308	Re: G size cylinders No worries. If you want to work it out with other cylinder sizes/numbers/pressures, here's the spreadsheet. If you're only using one supply cylinder (bank) just put zero for the pressure in the others. Cheers, Jason. OK, I don't seem to be able to attach an xls file, so here it is on my site: http://www.deepdiving.net/tools/cascading2.xls
(Online)

6th September 2007, 23:21	#8 (permalink)
opimoby New Member Current Rebreather/s: Evolution Other Rebreather/s: MK 15.X Join Date: Jul 2007 Location: Port Douglas, Australia Posts: 68	Re: G size cylinders Hey Jason thanks very much for your assistance...some people are really helpfull in these forums others well waste of space.....cheers Ross __________________ If you build it...they will come.. Last edited by opimoby : 6th September 2007 at 23:59. Reason: spelling mistake
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7th September 2007, 03:02	#9 (permalink)
bendomatic it's a girl due 20th May Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: Apr 2005 Location: Brisbane Australia Posts: 198	Re: G size cylinders well your question kinda indicates that you haven't got a clue, unless someone else is doing the decanting for you. rachel __________________ why deal with idiots on the net when you have to spend all day dealing with them at work.
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7th September 2007, 03:47	#10 (permalink)
PeteS Consent Issued! Current Rebreather/s: Inspiration Classic Inspiration Vision Other Rebreather/s: Join Date: Jun 2005 Location: New Zealand Posts: 511	Re: G size cylinders Quote: (Originally Posted by opimoby) Hey Jason thanks very much for your assistance...some people are really helpfull in these forums others well waste of space.....cheers Ross Well, your question concerns me, because it is about a very basic thing that is covered in various blenders courses. It suggests a lack of basic knowledge regarding the relationship between pressure and volume. Being spoon fed answers isn't always the best thing, understanding the subject is. Sorry to be a waste of space. How to work it out:- Get pressure and volume of your cylinder and mutiply them together, this will give the litres of gas in the cylinder. Do the same for your large cylinder. Add the two numbers together Divide that number by the total volume of both cylinders added together, and that will give you the final fill pressure. So the formula is:- ( ( P of J x Vol of J ) + (P of Dil x Vol of Dil ) ) / (Vol of J + Vol of Dil ) = Fill pressure in Bar __________________ Pete S. http://www.steggle.co.nz Every silver lining has a cloud
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