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Small propane (orange) gas cylinders - 3.9kg


Ian on Leo

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11 minutes ago, MtB said:

 

 

Hve you actually done this yourself?

 

What I don't get is what motive force makes the liquid gas flow down into the lower bottle, given I would expect the vapour pressure in the lower bottle to equalise with the upper bottle almost instantly the valves are both opened. 

 

The liquid propane in the lower bottle will surely boil in a flash and equalise the pressures, leaving only gravity to cause the flow, and a tube maybe only 1/4" in diameter will surely air-lock. Or vapour-lock rather, thus preventing any liquid flow. 

 

When they fill the bulk tanks the liquid gas in pumped in I reckon, so the vapour in the receiving tank condenses as the pressure rises. This can't happen when filling 'bottle to bottle'. 

 

 

Once the two bottles are connected the gas pressure in the lower bottle will be greater than that in the upper bottle due to the hydrostatic head of the liquefied gas. That will cause gas in the lower bottle to liquefy and gas will boil off from the surface of the liquid in the upper bottle. So there is a net transfer of liquid from the upper bottle to the lower. 

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19 minutes ago, MtB said:

 

 

Hve you actually done this yourself?

 

What I don't get is what motive force makes the liquid gas flow down into the lower bottle, given I would expect the vapour pressure in the lower bottle to equalise with the upper bottle almost instantly the valves are both opened. 

 

The liquid propane in the lower bottle will surely boil in a flash and equalise the pressures, leaving only gravity to cause the flow, and a tube maybe only 1/4" in diameter will surely air-lock. Or vapour-lock rather, thus preventing any liquid flow. 

 

When they fill the bulk tanks the liquid gas in pumped in I reckon, so the vapour in the receiving tank condenses as the pressure rises. This can't happen when filling 'bottle to bottle'. 

 

 

 

Yes I have done it, and regularly do it on the smaller Camping size cylinders (100g, 230g & 500g)

It is the liquid that you are transfering and it seems to be just gravity that allows it to run from the top cylinder to the bottom cylinder - as I said you gate a much quicker flow if the receiveing cylinder is a lower temperature that the donor cylinder.

You are the 'gas man' with the knowledge, I just "do it"

 

My camping gas transfer gear is very simple (as the cylinders are much more handleable), simply screw onto both cylinders, open the tap and it fills.

 

I have a variety of adapters to allow for filling the cylinder from 'a cigarette lighter refil ronson can' to a 47kg propane cylinder, so on longer trips I can always find gas, even if it is just a lighter refil can at a newsagents.

 

 

 

 

 

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Edited by Alan de Enfield
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1 hour ago, Captain Pegg said:

 

Not refilling. They supply bottles but have limited stockists hence it will require a bit of planning.

 

I wondered why it took as long as it did for someone to mention FloGas so I'm still waiting for someone to throw a curveball...

 I'd started a thread earlier asking whether FloGas was a viable solution - when I get back to Frome I shall search out the nearest stockist - I think it's either that or safefill for me

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2 minutes ago, bizzard said:

And I do it regularly, from an aerosol into my fag lighter. :closedeyes:

 

Exactly - and it is no more difficult to do it cylinder to cylinder.

 

Thankyou - I had meant to say that but forgot.

 

You cannot 'over pressure' as the pressure ratings of the cylinders are the same, and if you avoid overfilling (80% max) it is not going to explode if left in the sunshine.

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Just now, Alan de Enfield said:

 

Exactly - and it is no more difficult to do it cylinder to cylinder.

 

Thankyou - I had meant to say that but forgot.

 

You cannot 'over pressure' as the pressure ratings of the cylinders are the same, and if you avoid overfilling (80% max) it is not going to explode if left in the sunshine.

 

And there's absolutely nothing stopping naive DIY refillers from filling to 100%. Given the lack of knowledge regularly seen on this forum by newbies (on pretty much all subjects), do you really think this is a good idea?

 

If somebody blew up their boat and killed themselves would you just say "Well that was stupid, it's their fault, I wouldn't have done that"? Because that's what your posts are coming over as saying... 😞

 

There are very good reasons why unskilled people are not permitted to do things which can be extremely dangerous to themselves and especially others, and DIY refilling of gas cylinders looks like one of them to me.

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9 minutes ago, magpie patrick said:

 I'd started a thread earlier asking whether FloGas was a viable solution - when I get back to Frome I shall search out the nearest stockist - I think it's either that or safefill for me

 

I missed that. It's hidden in the Boat Equipment section. I'll have a read,

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9 minutes ago, IanD said:

 

And there's absolutely nothing stopping naive DIY refillers from filling to 100%. Given the lack of knowledge regularly seen on this forum by newbies (on pretty much all subjects), do you really think this is a good idea?

 

If somebody blew up their boat and killed themselves would you just say "Well that was stupid, it's their fault, I wouldn't have done that"? Because that's what your posts are coming over as saying... 😞

 

There are very good reasons why unskilled people are not permitted to do things which can be extremely dangerous to themselves and especially others, and DIY refilling of gas cylinders looks like one of them to me.

 

If they have been informed of how to do it properly and they do not use the correct methods,  (and that applies to anything from electrical wiring, to driving a car to helming a boat, to refilling gas cylinders) then - yes - Let Darwin come into play.

 

If they try and 'do potentially dangerous things' without asking for help or instructions to do it, then, let Darwin come into play.

Edited by Alan de Enfield
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Just now, Alan de Enfield said:

 

If they have been informed of how to do it properly and they do not use the correct methods,  (and that applies to anything from electrical wiring, to driving a car to helming a boat, to refilling gas cylinders) then - yes - Let Darwin come into play.

 

So, it's OK for them to blow themselves up then?

 

How about their wife who also lives on the boat, or children, or the people on the boat next door -- is it also OK for Darwin to kill them?

 

Nice one Alan, you're really coming over as a warm, feeling human being -- not... 😞

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4 hours ago, Alan de Enfield said:

 

You fill to 80% and that is done by weight.

Work out what 80% of the weight of gas that the cylinder is rated as (ie 80% of 3.9kg = 3.1kg)

Stand the empty cylinder on the scales, zero the scales and as you fill watch the weight and when to gets to 3kg STOP.

 

This gives you a safe 'underfill' with expansion space for hot weather.

I think you need to be quite sure the cylinder is empty when simply weighing the addition. Comparing the weight of the cylinder with its stamped tare will be a start.

But is there a technical reason for not filling to the full, nominal capacity? Presumably that leaves sufficient space for expansion when Calor does it.

I can see that you might not want to cut it too fine when using ancient bathroom scales or whatever, but as a principle?

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if you want an example why not to overfill LPG tanks….
 

Apparently it’s been hot enough today to cause the bulk LPG tank at my partners school to vent….Calor were called out after a smell of gas was reported…they are now cooling it down with a hose…although my partner and the other female staff are most disappointed they didn’t get firemen apparently…

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Well I have to break the habit of a lifetime and agree with @IanD here.

 

Filling cylinders is not something I would be encouraging anyone to do unless it was being done with cylinders designed as such eg Safefill/Gaslow and it was being done from an LPG pump on a forecourt.

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4 hours ago, Alan de Enfield said:

 

Yes I have done it, and regularly do it on the smaller Camping size cylinders (100g, 230g & 500g)

It is the liquid that you are transfering and it seems to be just gravity that allows it to run from the top cylinder to the bottom cylinder - as I said you gate a much quicker flow if the receiveing cylinder is a lower temperature that the donor cylinder.

 

 

 

Do you stand the bottom cylinder on a pair of scales while you fill it        (why do we still refer to a pair of scales when there is only one)

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4 hours ago, IanD said:

 

And there's absolutely nothing stopping naive DIY refillers from filling to 100%. Given the lack of knowledge regularly seen on this forum by newbies (on pretty much all subjects), do you really think this is a good idea?

 

If somebody blew up their boat and killed themselves would you just say "Well that was stupid, it's their fault, I wouldn't have done that"? Because that's what your posts are coming over as saying... 😞

 

There are very good reasons why unskilled people are not permitted to do things which can be extremely dangerous to themselves and especially others, and DIY refilling of gas cylinders looks like one of them to me.

All Calor valves have a blow out red plug which will vent before any explosion.

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46 minutes ago, Tracy D'arth said:

All Calor valves have a blow out red plug which will vent before any explosion.

If you’ve ever seen one vent I don’t think you’d want to be that close to it…..they can take off rather well. 

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Just now, Tracy D'arth said:

But that is correct then.  Better than after don't you agree?

 

Not a rude post or offensive. humour intended. OK?

 

I'm not sure it makes much difference to the corpse whether the overfilled cylinder goes kaboom without any warning, or a little red plug blows out and *then* the boat goes kaboom, they're just as dead either way... 😉

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1 hour ago, ditchcrawler said:

Do you stand the bottom cylinder on a pair of scales while you fill it        (why do we still refer to a pair of scales when there is only one)

 

You can do, hence 'zero the scales, but generally I don't  because I'd be getting an exaggerated figure from some of the weight of the other cylinder.

 

Weigh it empty. Note the weight.

Connect up the decanting hose for 2 or 3 or 4 minutes (not long anyway), disconnect hose and re weigh Cylinder, deduct empty weight and that is how much gas you have put in in 2, 3 or 4 minutes, that then gives you an idea of how long it will take to "fill" I stop again and weight it when I reckon I'm at about 75% see what the nett weight is, then can add  a bit more as required.

 

Better to underfill by a few percentage points than over fill.

 

Remember that Calor's (say) 3.9kg is the 80% fill to allow for the expansion space. I am saying fill with 80% of 3.9kg so you are in fact only filling to 80% of 80%  so the cylinder is actually 80% 'filled' by weight but only 64% filled by volume.

 

 

2 hours ago, Tacet said:

I think you need to be quite sure the cylinder is empty when simply weighing the addition. Comparing the weight of the cylinder with its stamped tare will be a start.

But is there a technical reason for not filling to the full, nominal capacity? Presumably that leaves sufficient space for expansion when Calor does it.

I can see that you might not want to cut it too fine when using ancient bathroom scales or whatever, but as a principle?

 

 

See my answer to ditchcrawler above.

Edited by Alan de Enfield
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1 minute ago, Alan de Enfield said:

 

You can do, hence 'zero the scales, but generally I don't  because I'd be getting an exaggerated figure from some of the weight of the other cylinder.

 

Weigh it empty. Note the weight.

Connect up the decanting hose for 2 or 3 or 4 minutes (not long anyway), disconnect hose and re weigh Cylinder, deduct empty weight and that is how much gas you have put in in 2, 3 or 4 minutes, that then gives you an idea of how long it will take to "fill" I stop again and weight it when I reckon I'm at about 75% see what the nett weight is, then can add  a bit more as required.

 

Better to underfill by a few percentage points than over fill.

 

Remember that Calor's (say) 3.9kg is the 80% fill to allow for the expansion space. I am saying fill with 80% of 3.9kg so you are in fact only filling to 80% of 80%  so the cylinder is actually 80% 'filled' by weight but only 64% filled by volume.

 

I'm sure the kind of idiots we see or read about every day on the internet will be perfectly capable of following your admirably detailed instructions carefully... 😉

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Just now, Alan de Enfield said:

 

It is their choice and their lookout if they don't.

 

And if their boat is next to yours when it goes kaboom...?

 

Actually that wouldn't bother me so much, it would be poetic justice for you having encouraged DIY bottle refilling -- after all, Darwin works for everyone, doesn't it?

 

But if they were moored next to a boat of nuns looking after several orphaned children, I'd be rather sad... 😞

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