LPG: Propane or Butane

[Lightspeed]

Considerable focus at the Lightspeed homestead on bottled gas at the moment.

We've gained some knowledge that might be useful to others setting up their preps to include LPG

It seems that not all gasses were created equal and as usual there are opposing benefits that must be considered.

We have off grid gas cooking, running from LPG that is piped into the kitchen from a ventilated secure outside storage area.

First up LPG cannot just be connected to a domestic gas hob.

JETS: the Jets have to be replaced with the appropriate grade (these are G20 for Natural Gas, G30 for Butane and G31 for Propane). We have found that both Propane and Butane burn OK with G31 jets.

REGULATOR: A gas regulator is needed to adjust the LPG gas pressure to match that needed by the burning unit. ( Natural Gas is delivered at the correct pressure by the utility company, so no regulator is required in the town gas supply) For Propane the regulator must be 35mb pressure and for Butane 28mb. There are now available regulators for camper vans that will connect and supply both gas types from a single unit.

POWER: The energy that is derived from various fuels is measured in BTU. Butane has the highest energy value, meaning that each Kg of Liquified Butane burns to produce more heat than either Propane or town gas.

Liquification Temperature: This was a new one to us and turns out to be critical. This is the temperature at which gas turns from gas to liquid, and in reverse from liquid to gas. If the temperature of compressed liquified gas is too low it will not, turn back to gas when depressurised. ( and the depressurisation process drops the temperature as well)

Below is a table of what we've found out. For us the decision was clear, we had to go with a propane LPG system in order to have reliable mid winter gas supply. The reduced energy value of propane we've found to be almost exactly offset by reduced cost per litre. The only downside is that we have to store approx. 20% extra volume.

Gas Type / Liquification temp / BTU / Regulator pressure
Propane / -42C / 2500 / 35mb

Butane / -1C / 3000 / 28mb

Natural / -162C / 1000


Hope this is of use to someone, but suggest you research your own primary data in making final decisions.

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Mrs Lightspeed reports the Propane powered hob, fitted with C31 jets is performing perfectly.

In survival mode ( food heating only), 10Kg of propane lasts us 2 to 3 months.

[Nix]

Good info LS, as you say, advantages and disadvantages for each gas. Agree, propane definitely the one to go for if using during winter months.

I've been told that butane is a little safer than propane, fumes wise, if your intention is to use it as an energy source for eg a camping gas fire indoors. If such a usage is envisaged, then keep in mind that you should have a well ventilated room which kind of defeats the objective somewhat!

[Lightspeed]

Good point about ventilation Nix.

Using propane on the hob, we have not altered ventilation at all and are suffering no ill effects.

So I think that in old, traditional houses that are a bit draught-leaky, no additional ventilation is needed. Its modern hermetically sealed, double glazed homes that may present a problem.

[Geordie_Rob]

Grab yourself a carbon monoxide detector. Cost about £10 & the battery lasts ages. Better safe than sorry.

[Lightspeed]

Thanks GR, good point

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