# Propane vs LPG vs Butane



## Rapide561

Hi

I know that Butane could freeze in the cold. Other than that are there any differences with the above?

Also, I used LPG from the petrol station to fill the Gaslow system. Is this the same stuff as in a Calor bottle?

Finally, do all three do the same amount of "work" per litre. For example, if one litre of LPG would boil a pan of water for three hours, would Butane do the same?

Does any one know how this compares to "British Gas" or similar?

Finally, here, LPG is pence per litre.

In Italy, it is euros per kilogramme. Is LPG like water - one litre = one kilogram??

This is rather technical for me - especially at 0821 on a Friday morning!

Rapide561


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## Mikemoss

Too technical for me, too, at any hour! No doubt the members with larger foreheads will soon provide chapter and verse but all I do know is:

Butane and Propane are both LPG (liquefied petroleum gas)
Butane is in blue bottles and is no good in winter.
Propane is in red bottles and is fine in winter.

To be honest, that's probably all any of us really needs to know. Other than the fact that they both need very careful handling - a BLEVE (boiling liquid expanding vapour explosion) is the potentially lethal result of allowing any LPG bottle to be expopsed to flame or excessive heat. Having seen film of these things happening, you definitely do not want to go there.


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## 88966

Hi Rapide 561,

There are dissertations on this subject if you care to search the forums.

However, I will try and answer your questions simply.

As has been said both Propane and Butane are LPG's. As far as you are concerned they are broadly similar with the exceptions that Propane freezes at a considerably lower temp. than Butane and has a slightly higher calorific value (and is often cheaper). This is the main reason for using Propane in the winter.

The gas you are calling LPG, I think is Autogas as sold at filling stations. This is primarily Propane but I believe it does have a little Butane added to improve combustion ? It works absolutely fine, those of us that have gas tanks fitted use it all the time.

As far as weight is concerned, LPG is about half the weight of water. I am not going into the economics - too complicated for me - I just buy it when I need it .

Best of luck,


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## Rapide561

*LPG*

Thanks Bill

The reason I asked about weight is as follows.

Here, Morrisons are selling LPG at 39.9p per litre.

In Italy it was 0.75 Euro (about 57p) per Kilo.

Is a kilo of gas therefore like 2 litres?

I am trying to get my head around the pricing etc!

Any more helpers - always appreciated

Rapide561


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## Rapide561

*LPG*

Hi again

My friend the Chemistry teacher e mailed me this

Properties

Propane Butane 
Molecular weight 44.1 58.12 
Explosive range in air 2.1 - 9.5 % vol 1.6 - 8.5 % vol 
Boiling point - 42.1oC - 0.5 oC 
Freezing point - 187.8 oC - 138 oC 
Gross energy per unit volume MJ/L 25.5 28.7 
Density @ 15 oC kg/L 0.510 0.580 
Litres per tonne 1960 1720 
Motor octane number (MON) 95.4 89 
Research octane number (RON) 100 92

given that, as Bill suggested, LPG is about 50% the weight of water, then 2 litres of LPG weighs one kilogram

It is therefore cheaper in Italy than here.

So, I have 2 x 6kg cylinders. 12 kg must hold 24 litres of gas?

Oh stuff it, I will just fill it and use it!

Rapide561


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## 88966

That's the spirit (or the gas) !!!!!


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## peejay

Hi Rapide,

Just to confuse the issue even more :roll: 

Unlike the UK, LPG sold at filling stations abroad is rarely all propane, sometimes a high proportion of butane is added, can be as much as a 50/0 mix.

pete.


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## 88966

Hi Pete,

You may be right, I was told that in Portugal it is usually about 5% Butane.


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## Rapide561

*LPG*

Oh Brill PeeJee

So I might even freeze to death if the heater conks out!

How re-assuring!

Rapide561


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## haylingchrist

Some practical experience - I'm in the French Alps at the moment. On a couple of fairly cold mornings (-15C) my LPG tank would not produce enough pressure to work my Truma 6.5Kw heater.

Each time the tank was no more than half full, which shouldn't be a problem but may be significant. We also have a propane bottle and got round the problem by supplemented the LPG tank with this for a couple of hours.

A local told me that LPG here is a Propane/Butane mix and an installer in Grenoble advised against relying on it in Alpine winters.

A chap in a Clou I spoke to at St Gervais said his tank is fitted with a heater which operates below -6C. He fitted the tank himself so should know. If anyone knows where I could get one, I'd be interested.

Chris


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## Ocsid

The underlying problem with using LPG at low temperatures,is that in the "vapour take off" arrangement used in our applications the butane progressively gets left in the bottle. So irrespective of the % in the forecourt supply it builds up in the vans storage bottle over time. Only by coming into warmer conditions and "emptying" i.e. using up the then available butane , in the cylinder will you get over the problem. It should start reducing above about zero C but needs to be nearer 6 C to really start clearing it. 
Vehicles use "liquid take off" so this is not an issue for them as the name implies they draw off the liquid mixture both the butane and propane.


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## 88966

Hi Ocsid,

That's a very interesting point.

I shall have to make sure I stay in warmer climes !!


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## haylingchrist

Good point Ocsid. Sounds like a plausible explanation for the symptoms I'm seeing.

Chris


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## Bagshanty

BillD said:


> Propane freezes at a considerably lower temp. than Butane and has a slightly higher calorific value (and is often cheaper).


I'm not sure this is correct. Whilst working out how to take the maximum amount of stored heat abroad a few years ago, (using figures published in MMM & supplied by Calor, I think), I estimated that a 7KG butane bottle holds 25%more heat than a 6 KG propane bottle.

As te bottles are sitting in a cupboard, albeit unheated, I've had no problems throughout the winter, even with frost on the ground.

However, I am planning to fit a Gasow refillable to my new Rapido.


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## 88966

Hi Bagshanty (I like that name - you must be ex Andrew?),

I am not sure which part of my answer you didn't like. I emphasise that my answer was intended to be a simplified one for the original enquirer !

I did use the expression freezing whereas technically I should have said the boiling point (ie where the liquid LPG gasifies) is much lower for Propane than Butane. The technical details of the 2 gases are contained in the post by Rapide561.

I am happy for you to do the calcs. about heat per bottle, but remember there is about 17% more weight of gas in the Butane bottle - oh I'm going for a liedown !!!!!!!!!!!!!


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## Bagshanty

Hi BillD. Yes, ex Andrew. ( www.hmsbacchante.co.uk - "The Bagshanty")

"Didn't like" is a bit strong - but my comment was about the calorific value of butane being higher than propane. This is indeed contrary to popular opinion. The higher pressure ( & hence greater rate of take off) of propane was presumably intended to compensate for that.

But in terms of taking sufficient gas abroad - butane will last longer than propane, all things being equal (which they seldom are!)


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## cabby

all this about not getting the heaters to work in very cold conditions,has anyone had problems with diesel heaters.like an eberspacher.


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## 88724

No


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## Bagshanty

BillD said:


> .... Propane ..... has a slightly higher calorific value (and is often cheaper).


Keen to find the truth about this, I did some Googling, and there's masses of info out there.
I discovered it is difficult to compare like with like. Calorific value depends how you measure it. CV of propane is 2516 BTU/Cu ft, CV of butane is 3280 BTU/Cu ft

However, propane is also 21591 BTU/lb, against butane 21221 BTU/lb

Propane max flame temp = 3595 deg F

butane max flame temp = 3615 deg F

To make sense of all this, use the Wobbe Index, which takes into account specific gravity and CV, thus:

Wobbe Index = (Gross heating value)/(square root of specific gravity)

WI for propane = 2034
WI for butane = 2319

I.e. butane carries 14% more available heat
and butane bottles are 19% cheaper, weight for weight (more or less, based on 6/7 Kg bottles.)

BUT - propane doesn't freeze even in very cold winters. I well remember 25 years ago spending a winter in a very small caravan, with external butane bottles. Reurning one very cold night after a weekend away, I had to use a candle underneath it to get any gas at all (and changed to propane the next day)


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## 88966

Well that's cleared that up !!

It's a strange thing that most of the 'commercial' tasks seem to use Propane, like gas cutting, engine conversions, etc. Surely it can't be just because of the freezing/boiling point.


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## Pusser

I have been investing Butane v Propane and the info I got, which appears important to me is this.

Butane does not change from liquid to gas at freezing point and below and will either work poorly or not at all. However, it is not at such a high pressure as Propane which does work in the cold. It says quite clearly that Propane should not be kept in the home because of its high pressure and as my gas position is in the motorhome then Butane has to be the one for me. Also, while we are using it, I would imagine that the tempreature should not drop below freezing inside and so negates the need for propane. If it drops to below freezing while I am not using then who cares...


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## Scotjimland

Calor's own site answers most of these questions, try here for FAQs

http://www.calor.co.uk/faq/which-gas.htm

Re commercial use, builders, workshops etc use propane as it can be stored safely outside all year without freezing, it also comes in much larger and therefore more economical sizes, the max size of butane is 15kg, propane 47kg.


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## DABurleigh

"I would imagine that the tempreature should not drop below freezing inside and so negates the need for propane. "

Pusser,

I would recommend Propane nevertheless 

The vapour pressure of Butane gets unusable at around 4 deg C, not freezing. Now, you may think it won't get to that but it easily can if you're using it over the winter months (that's the 363 days in total on each side of our summer of two sticky days, a swallow and a thunderstorm) with the heater going full whack.

Counter-intuitive? That's because the closed locker is well insulated from circulating warm air, and as you use the gas the latent heat of vaporisation (think cooling effect if you blow across the damp back of your hand) rapidly cools the cylinder below the ambient it was at.

Some people then try to avoid this by insulating the cylinder, which makes the situation worse.

Dave


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## Boff

BillD said:


> It's a strange thing that most of the 'commercial' tasks seem to use Propane, like gas cutting, engine conversions, etc. Surely it can't be just because of the freezing/boiling point.


Sometimes yes, sometimes no, that depends on the application:

LPG engines take their "gas" anyway out of the liquid phase and lead it through a device called "evaporator" (something similar to a carburettor) before feeding it into the cylinders. So it does not make much of a difference whether propane or butane is used, and this also explains why nobody (except motorhomers...) complains about the propane/butane mixture that is sold at continental fuel stations at the LPG pump.

Other commercial applications sometimes use very large amounts of gas in a short time, and here in fact the evaporative cooling effect could cool down a butane bottle so much that even in summer butane would cease to evaporate.

Also many commercial applications (e.g. at construction sites) require to be independent of the temperature, so butane is not an option.

Best Regards,
Gerhard


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## 116269

I found this in Alde Uk's FAQ section

Q.Propane or butane – what type of LPG (liquid petroleum gas) should I use?

Propane. Alde UK recommends the use of propane in all Alde (and SMEV) systems within the UK.

The operating temperature ranges of propane and butane are different, and will impact performance even at mild temperatures. The gas in a smaller bottle will cool quicker as it is tapped than in a larger bottle, and bottles chilled overnight may not warm to operating temperature again during the day. Thus the size of a bottle and the temperature at which it's stored will also impact performance.

BS 5482 Part 1 states, "For butane cylinders, satisfactory service might not be obtained at temperatures of less than 10 °C; the most suitable temperature range is from 13 to 30 °C. For temperatures less than 13 °C, the use of propane should be considered."

Propane will operate down to -42 °C and is more suitable for the British climate.

Be aware that Campingaz (formerly Camping Gaz) is butane, and therefore not recommended for use our systems.


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## blondy

Pusser said don't keep propane inside,
All LPGs should be kept in a ventilated compartment with dropout holes in the floor unless outside, as LPG is very heavy and can spread if there is a leak, While in business I heard of many Heating engineers having small sudden fires while bleeding the pipework through to the boiler. some were injured.
You must treat both gases the same for safety


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## 116388

As a soon to be full timer I have swayed away from the potential use of a wood stove to keep warm in winter. My camper has an underslung LPG tank and I would like to cook and heat from it at the turn of a tap.

So, to summarise I think I am correct with the following:

*Propane for a all year round hassle free LPG source as long as it is stored outside of the living area.*

I only started to look into this about 20 minutes ago so this thread has been very helpful and I thank everyone who has contributed.

Shane.....


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## Rapide561

*Propane*

Hi

I use Calor Propane and have had no problems what so ever.

Russell

I love it when old threads like this pop up!


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## 116388

*Re: Propane*



Rapide561 said:


> Hi
> 
> I use Calor Propane and have had no problems what so ever.
> 
> Russell
> 
> I love it when old threads like this pop up!


Hi Russell,

I'm happy that you're happy! :lol: Do you run a heater from your Propane? Could you point me in the right direction for where I might be able to buy one?

Cheers,

Shane.....


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