6kg calor lite - how long will it last?

[jamestaylor18]

Hi all, I know there isn't an exact answer, but how long roughly will I get out of a 6kg calor lite cylinder?

I've done about 4 weekend trips so far, and am in Devon now for a week. The gauge is still saying full!

I only cook with gas, I used EHU for water heating, and don't use the heating at all as the van is plenty warm enough! I have cooked a fair few oven meals, and use the grill most mornings. Even did a roast dinner one weekend!

 

[WoodlandsCamper]

The gauge is still saying full!

DON'T TRUST IT. Ours was saying full last year and the OH couldn't get the hob to light, due to an empty cylinder. :evil:

Take the cylinder out and weigh it with a set of luggage scales. A full Calor Lite cylinder weighs 10.5 kg, so an empty one weighs 4.5 kg. Don't take the risk of believing the gauge like I did.

 

[jamestaylor18]

I don't trust it, I can't have much left in it to be honest! The site I'm on sell the lite cylinders, so i plan on getting a replacement as soon as it runs out ( hopefully not half way through tea! )

 

[ProfJohnL]

The only practical way of knowing accurately how much gas is left in a cylinder is to weigh it. Then find the tare weight ( weight when empty) which should be stamped on the bottle, subtract smaller figure from the bigger and the answer is how may kg of gas you have left.

You can work out a worst case estimate of of time remaining, buy checking all your appliances data plates which should quote the maximum gas consumption rate in grammes per hour (g/hr). add together all those for the appliances you use, and work out how long you use them for, then divide that total gas consumption rate into the weight of gas remaining to work out the number of hours worth of gas you have left.

 

[Raywood]

Weighing it is the only way to be sure what is in it. You do however need two cylinders in the long term as sods law dictates that it will actually run out when you are cooking at night five minutes after the site shop closed.
How long it will last depends on how often you use it and what for and there is no easy answer to that but with us normally using the electrics for almost everything except the oven we get at least a year out of the cylinders usually more.
I will normally have two cylinders one in use and one empty. I check the one we are using simply by lifting it from time to time and compare it with the empty one. I basically change it when my nerves get the better of me and avoid my wife's wrath if it went in the middle of cooking breakfast with no spare available. So far it has worked.

 

[Mel]

Our regular ( not lite) calor6kg was new in August 2015. Since then we have done 2 whole weeks and at least 10 weekends. However we only use gas for cooking and EHU for everything else. We don't keep a spare cylinder as when it runs out half way through rtea whatever is uncooked will get bunged in the microwave or on the electric hot plate and gas will wait until the site shop reopens. Living on the edge,us B)
Mel

 

[RayS]

I understand the indicator on the calorlite bottle does not start to change until you get down to 25% full / 75 % empty and is only meant to be an indication of 'getting empty' rather than a 100% contents gauge.
As others have said the only reliable way is to weigh. Baggage scales sold for checking suitcase weight for airlines are just right for the job - they usually go up to 50kg - are easy to use and cheap to buy - around £10. You can check the accuracy by getting say an 8 litre water container, weighing it empty, filling with water, weighing again. The difference should be 8kg give or take a few grams. Or put a couple of known weight things e.g. bags of flour or sugar into a supermarket plastic bag and weigh this. the weight of the bag can be ignored. Google - airline baggage scale or look on Amazon - lots to choose from.

 

[WoodlandsCamper]

Baggage scales sold for checking suitcase weight for airlines are just right for the job - they usually go up to 50kg - are easy to use and cheap to buy - around £10.

Our scales are dial ones like these but only have the 22 kg scale marked, not the pounds as well.

 

[saint-spoon]

Personally I prefer to take a full spare with us when we go. It’s not so important if we are getting EHU but off line the fridge runs on gas so it’s always handy to be able to keep that running. As has been said before you need to weight the bottle and subtract the tare weight to find out how much gas is left in the bottle.

 

[Firkle]

James,

Our usage is similar to yours and so far we have had an eight week trip in Scandinavia and 10 days in the UK and our original Calor Lite is showing half full on the guage.

Because we usually tour in Europe, I normally carry two Calor Lites and would expect at least another week out of this one.

 

[WoodlandsCamper]

....and our original Calor Lite is showing half full on the guage.

DON'T TRUST THE GAUGE. :evil: They are extremely inaccurate and can stick. Weigh the bottle to be sure.

 

[saint-spoon]

as an engineer I am intrigued as to how the gauge is supposed to work.
Whilst there is still liquefied gas in the cylinder the pressure is dependent on the temperature of the cylinder contents (and type of gas), the pressure will only start to drop once all of the liquid gas has evaporated.

 

[ProfJohnL]

as an engineer I am intrigued as to how the gauge is supposed to work.
Whilst there is still liquefied gas in the cylinder the pressure is dependent on the temperature of the cylinder contents (and type of gas), the pressure will only start to drop once all of the liquid gas has evaporated.

Hello SS,

Yes that is the obvious conclusion, but there is a bit more to t that that:-
The type of the gas in your cylinder is not perfectly pure butane or propane, this is because the commercial fractionisation of crude oil is not precise. The gas will have some other fractions mixed in with it, sometimes added deliberately to bring its calorific values into the correct commercial range. Each different fraction will have its own pressure and temperature characteristics, and boil off temperatures. Generally speaking the lower the boil off temperature, the high its vapour pressure for any given temperature.

Consequently when you have a fresh cylinder it will have all the fractions its supplied with. As you start to use it, those fractions with a lower boiling point will tend to boil of and be used up first, But as the liquid is bubbling (boiling) it is mixing, so the proportions of the fractions in the vapour change slowly. As the cylinder is progressively used, you will be left with a greater proportion of lpg's with higher boiling points and thus slightly lower vapour pressures. Consequently over the life of a cylinder, you may see a reduction in the vapour pressure for the same temperature. Generally this change is relatively small, and as you correctly point out the biggest pressure drop will occur when all the liquefied gas has been evaporated, and you are literally running on fumes.

We must not also forget the temporary self cooling effect of the cylinder when the latent heat of vaporisation cools the remaining liquid in the cylinder, which drops the cylinders temperature, and in extreme cases causes frosting on the outside. The pressure will rise as the cylinder is able to take up heat from the atmosphere around it.

This effect is more obvious with butane than propane as propane naturally has a lower boiling point adn teh other gasses involved generally have higher BP's

 

[WoodlandsCamper]

as an engineer I am intrigued as to how the gauge is supposed to work.
Whilst there is still liquefied gas in the cylinder the pressure is dependent on the temperature of the cylinder contents (and type of gas), the pressure will only start to drop once all of the liquid gas has evaporated.

Hello SS,

Yes that is the obvious conclusion, but there is a bit more to t that that:-
The type of the gas in your cylinder is not perfectly pure butane or propane, this is because the commercial fractionisation of crude oil is not precise. The gas will have some other fractions mixed in with it, sometimes added deliberately to bring its calorific values into the correct commercial range. Each different fraction will have its own pressure and temperature characteristics, and boil off temperatures. Generally speaking the lower the boil off temperature, the high its vapour pressure for any given temperature.

Consequently when you have a fresh cylinder it will have all the fractions its supplied with. As you start to use it, those fractions with a lower boiling point will tend to boil of and be used up first, But as the liquid is bubbling (boiling) it is mixing, so the proportions of the fractions in the vapour change slowly. As the cylinder is progressively used, you will be left with a greater proportion of lpg's with higher boiling points and thus slightly lower vapour pressures. Consequently over the life of a cylinder, you may see a reduction in the vapour pressure for the same temperature. Generally this change is relatively small, and as you correctly point out the biggest pressure drop will occur when all the liquefied gas has been evaporated, and you are literally running on fumes.

We must not also forget the temporary self cooling effect of the cylinder when the latent heat of vaporisation cools the remaining liquid in the cylinder, which drops the cylinders temperature, and in extreme cases causes frosting on the outside. The pressure will rise as the cylinder is able to take up heat from the atmosphere around it.

This effect is more obvious with butane than propane as propane naturally has a lower boiling point adn teh other gasses involved generally have higher BP's

Information overload. Just weigh the damn cylinder.

 

[Raywood]

We do seem to be making a simple thing over complicated. Rather than take the cylinder out I just compare its weight with the empty one and it works for me.

 

[Martin24]

The simplest answer is until it runs out. At that point we just swap for the spare and get the empty one filled. It works for a simple soul like me that can't see the point in worrying about taking the scales with me and weighing a gas bottle.

 

[WoodlandsCamper]

Rather than take the cylinder out I just compare its weight with the empty one and it works for me.

How can you compare its weight without unstrapping it first and disconnecting the hose, and once unstrapped/disconnected you may as well lift it out in any case and weight it?

 

[RayS]

Most airline scales will go to the limit for checked in cases - that's what they are for after all. Te one I have is electronic, with digital readout and selectable to lbs. or kg It also bleeps helpfully once the measured weight has steadied and hold this reading until reset. I've lost the box long since but it came from Amazon. Folds up to about 7 x 3 x3/4 inches, quick connect strap to go round suitcase handle / hole in gas bottle top surround.

 

[Damian]

The simplest answer is until it runs out. At that point we just swap for the spare and get the empty one filled. It works for a simple soul like me that can't see the point in worrying about taking the scales with me and weighing a gas bottle.

I fully agree with you Martin.
You can give all kinds of highly technical jargon to explain a very simple conundrum.
When the gas runs out, the cylinder is empty !!!!!

 

[Hutch]

I am with Martin, when the wife says, is the food ready, and your having a beer and havn't noticed the botltes run out, just say another 10 minutes,

 

[ProfJohnL]

Hi all, I know there isn't an exact answer, but how long roughly will I get out of a 6kg calor lite cylinder? ...

James did not ask how will he know when the cylinder is empty, he was asking how long will the cylinder last, these are two very different things. For some people there may be an important reason for knowing, perhaps there is temperature sensitive medicines that need to be kept cool in the fridge, or some other as yet unexplained pressing reason.

The fact is if you want to know how long a cylinder will last, you have to know how much gas remains in the cylinder, and what your usage rate is. The only way to know how much gas remains with any precision is to weigh the bottle, and subtract the bottles tare weight.

How long it will last, requires you to work out your usage rate, which for thermostatically controlled devices is always difficult, but you can at least work out their usage if they were running 100% of the time, with the bonus you will know the gas will last longer than that.

I had got round the problem by by using an automatic change over regulator set with two bottles, As one bottle emptied, the system automatically switched over to the second bottle, allowing the empty one to be changed. This ensured the continuation of the supply, but it did need regular checking to establish when it had changed over, and when to replace the emptied cylinder.

Information overload? I do not apologise for the explanation in answers to a SS question.

 

[Dustydog]

Thanks Prof for reminding us of the OP question. We do seem to go off at tangents these days :silly:
I'm fully with Martin Damian and Hutch. For decades I have carried two ordinary 6kg propane cylinders.
Caravanning roughly 10 weeks of the year a full cylinder seems to last 6 months with our use . We predominantly use EHU. Our gas is mainly used for cooking and the BBQ.
In their infinite wisdom and probably connected to the Prof's explanation, when the cylinder nears the end a noticeable smell emanates from the lit burner. Yes she's just about empty. A quick cylinder change over. Yes the latest Calor kit is quick and easy change over . No need for the spanner of old.
I know a number of you use auto change and weigh the cylinder but in all honesty what's the point B)

 

[Parksy]

In all honesty although this query has raised a discussion there is no answer to the OP because no one knows which appliances are being used, for how long, the weather conditions at the time etc; There are too many variables to allow any true answer, the only way to find out how long your lpg will last is to carry two and to change over when the first bottle is used.
Over time, individual experience will provide an approximate answer for your own particular set of circumstances.

 

[rcpilot]

Actually it will last quite a long time, as I go what they call dry camping , I run my fridge on gas, cook with gas, heat water with gas and occasionally run the heating (if it is cold) and a full bottle will last about a week, but , and hear comes the crunch I have a refillable gas system so a 6kg bottle of gas costs me roughly £6 - £7 depending on what the price of auto gas is (same stuff)(propane)

 

[brian_c]

I'm guessing James that you only have the one bottle. So that being the case I can understand your need for some fairly reliable indication of what percentage of a full bottle remains.
Again I'm guessing, but if the indication shows that you are down to the last say 10 percent I suspect you will at that stage forsake the bit of gas that is left and exchange the bottle.
With the initial price of a calor lite cylinder i can certainly understand this thinking obviously if my guessing is correct.
So having said that I'm afraid that you are down to weighing the bottle after each trip to gain some indication if you are near the level you believe to be too risky.
Other members have explained the best method and the scales found by Woodlands Camper are a small price to pay against the obvious frustration of an empty bottle at an awkward time.
Another point is that not all sites carry the lite bottles so if you are sticking with the one bottle regular checking becomes a must really
Best wishes Brian