Which gas is best?

[dougbobbill]

We only use gas for our cooker, which will work with Butane or Propane. Which type should we use?

 

[Trek]

If you use it in the winter then its got to be Propane

 

[Jimbohorlicks]

Propane, if you use butane in the winter it can freeze up and not convert to a gas. Plus propane is more readily available, red bottles,.

 

[Wrighpm]

Either if not using in lower temperatures. Propane best all round choice. Butane or blue calor needs temps over 8 degrees to vaporise sufficiently to simultaneously feed fridge heating and cooker. So go propane or lpg.

 

[Bigbaz]

Propane if you don’t want to be caught cold some chilly morning.

 

[in h]

Although propane is the best for year-round use, the bottle fittings and regulators are different.
So if yours is set up for butane, changing to propane is not just a matter of choosing a different coloured bottle.

 

[Markd]

Propane will "boil off" preferentially in a mixed system so if you have on board refillable tanks then be wary with autogas when abroad in winter or you could end up retaining butane and eventually get nothing!
Obviously if you're using exchange bottles this isn't a problem. If you do any winter cooking then go for a propane system - the bottle connectors are different so choose one and stick with it unless you like messing around in the gas locker

Edit after inh - Looks like 'great minds' are at work here

 

[Molly 3]

Butane slightly hotter , propaine works better below freezing

 

[GeoffL]

This came up on another forum a few years ago and did the maths to calculate calorific value per bottle. A 7kg butane bottle provides significantly more heat than a 6kg propane bottle for about the same price and so butane is by far the best choice if you're never going to use it when the ambient temperature is below 8°C. However, it only took one Easter on Lomondside when the heating wouldn't work and the kettle wouldn't boil to convince me to use propane!

 

[channa]

Butane burns hotter than propane by approx 16 degrees academic nonsense really when you consider the overall temperature of a flame.

As mentioned at low temperatures around 5 degrees butane has difficulty gassing so propane is the better choice.late autumn to early spring

 

[GeoffL]

Butane burns hotter than propane by approx 16 degrees academic nonsense really when you consider the overall temperature of a flame.

As mentioned at low temperatures around 5 degrees butane has difficulty gassing so propane is the better choice.late autumn to early spring

However, here's the maths comparing 7kg butane cylinders with 6kg propane:
Calorific value of butane is 49.1 MJ/kg, so a 7kg cylinder can supply 343.7 MJ of heat.
Calorific value of propane is 50.4 MJ/kg, so a 6kg cylinder can supply 302.4 MJ of heat.
Thus, a 7kg cylinder of butane provides 41.3MJ (or 13.66%) more heat than a 6kg cylinder of propane. At the prices my local Calor stockist advertises (£25 for butane, £24 for propane), butane costs 7p per MJ while propane costs 8p per MJ - i.e. propane is about 12.6% more expensive per MJ.

As you suggest, if you're going anywhere likely to encounter low temperatures (I'd suggest 8°C), then propane is the only reliable solution. However, if you're only going to use your moho when the temperature will be at or above that, then butane is a cheaper, viable option.

 

[channa]

The problem with the maths Geoff is often the figures quoted are at standard atmospheric pressure with an ambient temperature of 15 degrees and at sea level. Certainly today in this part of York’s the temperature is warmer ,I am above sea level and not a clue the barometric pressure so the maths gets skewed before we start in real life terms

The other interesting variable and haven’t done the maths is what regulator is being used which determines the charge in the system. I suspect most figures banded about assume the standard 28 mbar butane 37 mbar propane. Which is lpg standard on most applications bar motorhomes where the standard is 30 mbar. So compared to the norm we have an undercharge on propane and overcharge with butane.

Then because of different expansion rates with similar lower explosion limits
One kilogram of butane at 15 oC and 1013.25 mbars (dry) produces 0.14 m 3 of gas. One kilogram of propane at 15 oC and 1013.25 mbars (dry) produces 0.54 m 3 of gas. .

Interesting as it all is there are variables that need to be considered

I personally use propane when buying calor , but normally use a safefill bottle which is a butane/ propane mix and never suffered the propane take off leaving butane situation someone described earlier. Albeit I understand how that can /could happen

 

[GeoffL]

It doesn't matter what the temperature and pressure are, or what regulator is being used. The calorific values I quoted are in unit energy per unit mass and both those are unaffected by either temperature or pressure even if the volume/density is. When a hydrocarbon is burned completely in air (or oxygen) the amount of energy released depends only on the number of molecules (i.e. mass) of fuel burned and the factors you introduced affect only the reaction rate but not the total energy 'stored' in the fuel.

 

[channa]

Of course temperature matters getting back on topic we both agree butane has difficulty gassing at low temps so temperature does have an affect.

Butane is summer gas propane is winter.as a general rule

 

[GeoffL]

Of course temperature matters getting back on topic we both agree butane has difficulty gassing at low temps so temperature does have an affect.

Butane is summer gas propane is winter.as a general rule

Temperature can only affect the reaction rate (below gassing point, that rate will be zero and the rate will increase with increasing temperature until the point at which the gas explodes). However, the total amount of energy remains unchanged. A 7kg cylinder of butane can provide 343.7 MJ of heat energy; a 6kg cylinder of propane can provide 302.4 MJ. The amount of energy per unit mass is the definition of "calorific value" and is completely independent of temperature (or pressure).

If you can't see this then I suggest we agree to disagree on that even though we agree that butane in the Scottish winter is probably as much use as a chocolate fireguard!

 

[in h]

However, here's the maths comparing 7kg butane cylinders with 6kg propane:

Do people still use those piddly little bottles? Far better value to use the ones that are about twice the size for very little more money.

 

[trevskoda]

I make my own gas and wife says i should regulate it as it seems to escape at the wrong moments.

 

[Markd]

I hadn't realised the calorific difference was as great as it is.
Might convert domestic BBQ to butane when bottles run out.
Having said that I'll have to compare price of 15kg bottles against 47 kg propane I'm using currently.

 

[Minisorella]

Do people still use those piddly little bottles? Far better value to use the ones that are about twice the size for very little more money.

Makes perfect sense for those who can fit bigger bottles into their gas locker... many of us don't have the luxury of that choice.

 

[Markd]

If you can only get in small bottles then going for refillable system makes even more financial sense - assuming you use a fair bit of gas of course.
Pay back always based on individual consumption but calor 6-7 kg cost is getting on for 5x autogas.
Whereas 13-15 is 'only' 3x - so almost good value