Hello and welcome to our community! Is this your first visit? 1. ## Decanting Pressure question

So if I have an 11 litre cylinder pumped to 200 bar & decant into an empty 12litre twinset how much pressure would I equalise out at ? I have 2 theories one ends up at 45 bar the other at 62 bar ?  Reply With Quote

2. 62.8bar but if you get creative with the isolator you can increase this to 70.6 (I think).  Reply With Quote

3. You have a total volume of 11+(12*2)= 35L

You have 200*11= 2200 litres of gas

2200/35= 63 bar

Both your twinset and your 11L will end up with 63 bar in them

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With the manifold closed, you could decant into one side of the twinset first. Then decant into the other side before opening the manifold.

In which case...

decanting into first side 2200/23 = 96 bar in first side

This leaves you with 96 bar in the 11 so 96*11 = 1056 litres of gas

decanting into second side 1056/23 = 46

Open the manifold... (96+46) /2 = 71 bar

In this case you'd have 46 bar in the 11 and 71 bar in the twinset  Reply With Quote

4. Originally Posted by colinicky So if I have an 11 litre cylinder pumped to 200 bar & decant into an empty 12litre twinset how much pressure would I equalise out at ? I have 2 theories one ends up at 45 bar the other at 62 bar ?
The pressures have to be equal if you equalise. Just add the volumes together and dive smallest by the total, then multiply by starting pressure

24+11 = 35L

11/35 = 0.3142

0.3143*200 = 62.84bar  Reply With Quote

5. The formula is P1 x V1 = P2 x V2

P1 (pressure 1) x V1 (Volume 1) = P2 (pressure 2) x V2 (Volume 2)

So pressure 1 is 200 bar x Volume 1 11 litres= 2200

We know V2 is 11 litres plus 24 litres = 35 litres so to solve for P2 (the resulting pressure) divide 2200 by 36 = 62.8 bar

If the twinset had air in it to start, say 100 bar, you would total the volume of air across both cylinders i.e. 2200 litres in the 11 litre plus plus 2400 litres in the twinset = 4600 litres divided by the total volume of 35 litres to give a resulting pressure of 131.4 bar  Reply With Quote

6. Everyone seems to be forgetting the effects of Charles Law  Reply With Quote

7. Originally Posted by Paulo Everyone seems to be forgetting the effects of Charles Law  Reply With Quote

8. Charles, Gay-Lussac and Boyles law are really just special cases of the ideal gas law with one of the variables held constant. I can never remember which is which and always think them all as PV=nRT. Originally Posted by Paulo Everyone seems to be forgetting the effects of Charles Law  Reply With Quote

9. Charles Cooks
Boyle Bubble
Daltons Partial Pressure
Henry is the other one - solubility  Reply With Quote

10. Originally Posted by NWdiver You have a total volume of 11+(12*2)= 35L

You have 200*11= 2200 litres of gas

2200/35= 63 bar

Both your twinset and your 11L will end up with 63 bar in them

--------------------------------

With the manifold closed, you could decant into one side of the twinset first. Then decant into the other side before opening the manifold.

In which case...

decanting into first side 2200/23 = 96 bar in first side

This leaves you with 96 bar in the 11 so 96*11 = 1056 litres of gas

decanting into second side 1056/23 = 46

Open the manifold... (96+46) /2 = 71 bar

In this case you'd have 46 bar in the 11 and 71 bar in the twinset

What he said  Reply With Quote

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