Gas issues. Is this true or a fabrication??? (1 Viewer)

Elvis

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Hi All

We have discovered that when our gas bottle is low (say 1/4 full or less but not empty) the fire will ignite but goes straight out & water heater will not ignite at all but the hob will light (all 4 rings) and cook for ever on full strength. When the bottle is full, all of the above will ignite and work as normal

We were told by the place we bought it form,that this is normal as the hob needs less gas..... mmmmmm sounds like bull to me and no one I have spoken to has heard ofthis before. It's an Elddis 2003 model.

Has this ever happened to anyone else out there??? And if so,what was the problem with it??? :Doh:
Thanks guys xxx
 
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Elvis

Elvis

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Gas issues

We use the small orange bottles :Smile:

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Drylander

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Hello Elvis,

I had a similar problem, at a New Year below Zero site and I was a bit puzzled (as I was on Propane not Butane) but, when changing the gas bottle, I found that the flexible hose between the regulator and the fixed copper piping had become kinked, thus constricting the (Plenty Of) Gas flow.

So I replaced that kinked flexible pipe & all was OK again.

I read recently that a faulty regulator can produce the same symptoms, they dont last forever and are fairly cheap at £6 - £12 quid: But beware, as I heard of a guy elsewhere who blithely paid £80 in ignorance!!

Bob L
 

Drylander

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Hello Again Elvis


I am not a professional gas expert, just a “User”, but since my initial reply have found the following which you might find also useful:

1. All about how to change/which types etc. Link Removed


2. Link Removed


My rule of thumb is (For Bottles AND Regulators, never mix the two up)

Red = Propane, for Winter/Cold climates

Butane = Blue for Summer/warmer climes


Personally I use those regulators (i.e from Towsure) with the Guage which indicates when you are running low. When you turn the gas off at the bottle the Indicator Guage should stay Green, with all appliances OFF, for several minutes to show whether you have any leaking joints, etc.

Hope that helps. Let us know how you get on; we can't have you paying for a full bottle and only using 3/4 of it!

Bob L

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Jul 29, 2007
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Hi as the gas level drops the vapourisation volume also drops as their is less gas to vaporise, so you will get much less flow volume from a 1/4 full bottle as you would from a full one.

Imagine you have two 10litre bottles with a common outlet, if you close off one bottle you will reduce the amount of gas comming out by about half, and its the same principle inside a bottle.

The answer if the pipework is ok, is a bigger bottle.

Olley
 

scotjimland

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Hi as the gas level drops the vapourisation volume also drops as their is less gas to vaporise, so you will get much less flow volume from a 1/4 full bottle as you would from a full one.

Hi Olley

Sorry, but I have to disagree, the bottle volume has nothing to do with the rate of vaporization , that is dependant only on the surface area of the liquid gas.. that is why bottles for BBQs and patio heaters are a dumpy shape, they have a large surface area in order to supply a large flow rate .. a bigger bottle will be better, but only if it has a larger diameter .. and hence a larger surface area for the liquid to vaporize.. not because it has a larger volume ..

hope I explained that ok ..

Jim
 

derekfaeberwick

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We live and learn Jim.:notworthy: I always thought the patio bottles were just "pretty" expensive.:Doh::thumb:

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Elvis

Elvis

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Wow, all fab advice, thank you very much all :roflmto: Sorry I can't reply to each individual but don't know how to yet.

Will keep you updated, will be talking to the business we bought it from again on Monday, they still have it there to be fixed so I can now tell them what you have told me and will see what they say.

Thanks again

Lisa:RollEyes:
 

Douglas

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Hi as the gas level drops the vapourisation volume also drops as their is less gas to vaporise, so you will get much less flow volume from a 1/4 full bottle as you would from a full one.

Imagine you have two 10litre bottles with a common outlet, if you close off one bottle you will reduce the amount of gas comming out by about half, and its the same principle inside a bottle.

The answer if the pipework is ok, is a bigger bottle.

Olley


PURE FICTION!!!

Doug...
 

GJH

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You don't say which Elddis van you have but on our 2004 reg (2003/4 model) Autoquest 100 we haven't had any gas problems. Our gas locker takes two 6Kg bottles and we use propane.

Having read about regulator problems possibly caused by leaching of plastics from conventional hose to regulator flexible pipes I replaced ours with a Gaslow steel pipe but otherwise no modifications.

Graham

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Jul 29, 2007
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Hi Olley

Sorry, but I have to disagree, the bottle volume has nothing to do with the rate of vaporization , that is dependant only on the surface area of the liquid gas.. that is why bottles for BBQs and patio heaters are a dumpy shape, they have a large surface area in order to supply a large flow rate .. a bigger bottle will be better, but only if it has a larger diameter .. and hence a larger surface area for the liquid to vaporize.. not because it has a larger volume ..

hope I explained that ok ..

Jim

Jim gas doesn't just vapourise from the surface, it vapourises from the middle, sides, bottom in fact everywhere, if you have less gas you will get less vapourisation.

Vapourisation is solely dependant on temperature, not surface volume.

Olley
 

scotjimland

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Jim gas doesn't just vapourise from the surface, it vapourises from the middle, sides, bottom in fact everywhere, if you have less gas you will get less vapourisation.

Vapourisation is solely dependant on temperature, not surface volume.

Olley

Hi Olley

as I said, I'm not a a gas expert.. just a sparky :roflmto: but I still stand by my explanation .. surface area not volume dictates max rate of vaporization .. at the same temperature.

Consider a pan of boiling water, the larger the diameter the more stream , if you need more steam you require a bigger diameter, increasing the volume of water won't produce more steam unless the diameter is bigger ..

let's agree to disagree until Google proves otherwise .. or 45er comes back on :ROFLMAO::ROFLMAO::ROFLMAO:
 

Munchie

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Contary to some replies the size of the bottle has no bearing on the issue. In our last m/home we had two 6kg bottles which we change to 13's. We now have two 11kg gaslow's. In our static we have two 47kg bottles. In all cases all functions work till the bottle is empty including heating. Hope this helps. ::bigsmile: Oh and the flow from the bottles is the same in all cases. Regulator? ::bigsmile:

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scotjimland

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Further information for those interested in the take off rate for different sized bottles.
scroll to bottom of page for chart

Link Removed

so bottle size does affect max take off rate ..
 
S

Shubberdog

Deleted User
LPG actually vaporises at a given pressure and is not dependent on surface area. I would say from the description of the fault that it is ether a faulty regulator or the pipe work is restricted in some way after the regulator (squashed, nipped, or kinked) :restmycase:
 

pappajohn

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Hi as the gas level drops the vapourisation volume also drops as their is less gas to vaporise, so you will get much less flow volume from a 1/4 full bottle as you would from a full one.

Imagine you have two 10litre bottles with a common outlet, if you close off one bottle you will reduce the amount of gas comming out by about half, and its the same principle inside a bottle.

The answer if the pipework is ok, is a bigger bottle.

Olley

not true Olley.

note item 2 at the bottom.

At normal temperatures and pressures, LPG will evaporate. Because of this, LPG is supplied in pressurised steel bottles. In order to allow for thermal expansion of the contained liquid, these bottles are not filled completely; typically, they are filled to between 80% and 85% of their capacity.(1) The ratio between the volumes of the vaporised gas and the liquefied gas varies depending on composition, pressure and temperature, but is typically around 250:1.
(2)The pressure at which LPG becomes liquid, called its vapour pressure, likewise varies depending on composition and temperature; for example, it is approximately 220 kilopascals (2.2 bar) for pure butane at 20 °C (68 °F), and approximately 2.2 megapascals (22 bar) for pure propane at 55 °C (131 °F).

(1) Ok i was wrong about the volume:Doh:....its 250:1 not 600:1

(2) thats 319psi (@55degC) in the bottle and must remain at or above this pressure to remain liquid until gas vapour is needed by opening a tap/valve so allowing the pressure to fall below 319psi and turning liquid to vapour until the valve is turned off and the liquid will continue to release vapour until the released pressure is replaced.

and you only need 30millibar. ( 0.43511323 psi )
as long as there is gas in the bottle then you will always get gas at the appliance at a uniform pressure, full bottle or not......unless it frozen!!

edit.......should have read 'liquid gas'
 
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Munchie

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not true Olley.

note item 2 at the bottom.

At normal temperatures and pressures, LPG will evaporate. Because of this, LPG is supplied in pressurised steel bottles. In order to allow for thermal expansion of the contained liquid, these bottles are not filled completely; typically, they are filled to between 80% and 85% of their capacity.(1) The ratio between the volumes of the vaporised gas and the liquefied gas varies depending on composition, pressure and temperature, but is typically around 250:1.
(2)The pressure at which LPG becomes liquid, called its vapour pressure, likewise varies depending on composition and temperature; for example, it is approximately 220 kilopascals (2.2 bar) for pure butane at 20 °C (68 °F), and approximately 2.2 megapascals (22 bar) for pure propane at 55 °C (131 °F).

(1) Ok i was wrong about the volume:Doh:....its 250:1 not 600:1

(2) thats 319psi (@55degC) in the bottle and must remain at or above this pressure to remain liquid until gas vapour is needed by opening a tap/valve so allowing the pressure to fall below 319psi and turning liquid to vapour until the valve is turned off and the liquid will continue to release vapour until the released pressure is replaced.

and you only need 30millibar. ( 0.43511323 psi )


as long as there is gas in the bottle then you will always get gas at the appliance at a uniform pressure, full bottle or not......unless it frozen!!


Precisely what I was trying to say...but you did it much better :thumb: (smart***e) :ROFLMAO::ROFLMAO::ROFLMAO:
 
S

sinbad1

Deleted User
Hi All

We have discovered that when our gas bottle is low (say 1/4 full or less but not empty) the fire will ignite but goes straight out & water heater will not ignite at all but the hob will light (all 4 rings) and cook for ever on full strength. When the bottle is full, all of the above will ignite and work as normal

We were told by the place we bought it form,that this is normal as the hob needs less gas..... mmmmmm sounds like bull to me and no one I have spoken to has heard ofthis before. It's an Elddis 2003 model.

Has this ever happened to anyone else out there??? And if so,what was the problem with it??? :Doh:
Thanks guys xxx

In my experience, and i have used many gas bottles over the years all my appliences work fine until just before the gas bottle depletes and then i assume that this is when the gas pressure drops.

Reading your particular issue it would point to,a probable issue with your water heater as you say all 4 burners on o your hob runs fine.( can't see that the water heater would use more than this)

It could be that there is some kind of restriction or it could be that the supply pipe is not big enough to supply the volume required.

Many of my ex fellow boaters failed their boat safety certificate because of their gas pipes were too small, and had to have them replaced with a larger dia to conform.

I am not corgi registered and IMO should be left to the experts. My advice would be to get a qualified corgi gas fitter to check your system out.

Regards

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vwalan

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hi sinbad. best not get a corgi fitter ,dont think they are qualified to check it.!
 
Jul 29, 2007
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Hi Papa and Ksebruce.
Sorry guys but that's incorrect, gas vapourisation is not a constant, to vapourise the gas must overcome latent heat, that is it must draw heat from the surrounding area to vapourise. As a very rough approximation water needs to draw 7times more heat to turn to steam than it took to raise it from cold. LPG has to do a is similar thing although I have no idea of the ratio, the only easy source is the liquid gas its self, that's why the bottle freezes on the outside. It takes heat from the surrounding gas which drops in temperature.

As it drops in temperature its vapourisation rate will slow, in theory it could drop enough to stop vapourising at all.

In the link to Calor that Jim gave there are two identical diameter bottles, but one is around 30% taller, so the surface area is identical between the bottles, only the quantity of gas has changed, and Calor say that you can draw approx. 30% more flow from the taller bottle. If Calor don't know what they are talking about; who does?
3.9 Kg 246 x 345 0.28 m3/h (7.5 kW)
6.0 Kg 246 x 490 0.42 m3/h (11 kW)

The flow will only remain a constant if the temperature does, lower the temperature and the flow will decrease, raise it and the flow will increase. Another variable is atmospheric pressure, but its not something we need worry about as variations in atmospheric pressure are to slight to make much difference.

So to sum up you will not get gas at a constant pressure if the take off is to fast, and that's what it boils down to, draw it faster than it can vapourise and the pressure drops, and why does it drop? because the liquid gets colder. And as calor state on their site, more volume equates to more vapour.

IF you are going to write in big letters DO YOUR HOMEWORK FIRST ::bigsmile:

Olley
 
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S

sinbad1

Deleted User
hi sinbad. best not get a corgi fitter ,dont think they are qualified to check it.!

Yes you are correct as of this year i belive a qualified Gas Safe engineer would have been more appropriate.

The point is all this techno guff is not really helpfull to the original poster particulary as he knows little about gas and its hazards.

Regards

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pappajohn

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my point is, Olley......the pressure in the bottle at 55degC is 22bar or 319psi. no matter if full, half full, quarter full.
at the outlet side of the regulator it is 30millibar or 0.43511323psi

at what point does the bottle internal pressure drop below 30millibar?.....when the liquid and any residual vapour has been used to a point where it can no longer operate the regulator.

for the pressure at the appliance to drop below 30mb the pressure feeding the regulator must drop below its minimum working pressure.

this is my understanding of what i have found on the internet......its not meant to be an argument.:Doh:
 
Jul 29, 2007
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Papa no argument ::bigsmile:

I stand by my first post that the volume of vapour gas potentionally available reduces as the liquid level falls. And this could be what his problem is.

Now this is all getting in the way of a much more serious subject; namely steering my boat "Olleys Tub" in the Volvo race game, (27194th position :ROFLMAO:) at the last count.

Olley

PS 29393 now :Doh:
PPS 31533 now :Doh::Doh:
 
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gazznsam

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as someone else mentioned, change the regulator, they care cheap enough, and are service items... even tho not many people change them at all.

after that, look for kinked pipes, if the run under the van as is common, a rock could have been thrown up by the wheels and hit the pipe run,

could also be muck in the pipework, where ever there is a low point in the pipe runs, heavy ends could collect... that's the oils, greases and gunk you get in the gas, it's perfectly normal, and dosent usually cause a problem, but that with the problem of some rubber regulator hoses leaching their oils into the system could be enough to partialy block certian pipe runs.

Heaters (water and expecialy space heaters) will deffo use more gas than a cooker, they need to as they heat up a lot more a lot faster,

Motorhomes are usually piped all in 8mm gas pipe, where as boats get 10 or even 12mm pipes to water and space heaters, and usually 8mm to the cooker, or maybe 10mm if it's a very long run.

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Munchie

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Hi Olley, I am not really arguing the rate of vapourisation case (don't know enough I'll leave that to the expert ::bigsmile:). All I am saying from much experience with all sizes and types of bottles that is iff there is enough gas to run 4 hobs then there is enough to fire up the heating. Can't be the regulator at fault as if it was the hobs wouldn't work. ::bigsmile:
 
Jul 29, 2007
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Hi Bruce now in 20007th position. gained over 10,000 positions overnight ::bigsmile:

Olley
 

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