Help Uk help with size cylinder

[Shewaitsforme]

Im rubbish with maths so help required. I see posts with USA metrics but no ides how to concert.

Basically need to know if a 20litre cylinder is enough or a 40litre for nitrogen. Will run it at the recomended 15psi. Really fustrating me now

 

[lukaszz12]

Neither of these is good enough. At 15psi(1 bar) the volume of compressed air is almost the same as the volume of the cylinder. Can't you find a 10l cylinder with 150/200 bar of pressure? These are really easy to get, at least where I live.

 

[Shewaitsforme]

Neither of these is good enough. At 15psi(1 bar) the volume of compressed air is almost the same as the volume of the cylinder. Can't you find a 10l cylinder with 150/200 bar of pressure? These are really easy to get, at least where I live.

Sorry i ment 15 fir the setting. The ones ive looked at are 200 bar or pressure. Was just unsure what size to get. I can afford a 20l or 40l cylinder.

Thabkyou

 

[TiredHorse]

First off, you don't want 15psi; that's a pressure rating. You want 15Lpm, which is a flow rating.

My best guess would be that you want at least a 3.5L cylinder, and a 7.8L would be better. BUT, I'm not familiar with metric sizing, I'm just pulling those numbers off this chart, working from what I know of US sizes: https://mathesongas.com/industrialgas/pdfs/Industrial-Cylinder-Dimensions.pdf In short, I'm assuming the litre-size is the liquid volume, not the total volume of compressed gas. You will want to double check me with this.

I have a 40cf, which is the same as a 7.8L. Running the maths, a 20cf/3.5L cylinder has ~566L of gas under compression, which would give you ~38 minutes at a flow of 15Lpm. That's cutting it a bit fine, but judging from the figures I see commonly cited (10-40min to death) would probably be adequate.

So if a 20L cylinder has a 20L liquid volume, yes, assuming it's compressed to a standard 2000psi, that should be much more than enough.

Have a look at that chart, and see if you can tell from the outside dimensions what size tank you're thinking of.

 

[lukaszz12]

Sorry i ment 15 fir the setting. The ones ive looked at are 200 bar or pressure. Was just unsure what size to get. I can afford a 20l or 40l cylinder.

Thabkyou

My fault.. If so then yes both are enough. An overkill actually.

 

[Shewaitsforme]

My fault.. If so then yes both are enough. An overkill actually.

Its a go big or go back to the psych ward i guess and i dont want to risk brain damage. I want to be down and out.

 

[Final Escape]

40 is huge, I accidentally got the bigger one but 20 should be good even if u practice a little