How to convert from cubic meters to kilos

Hello,

I have bought a Tortilla making machine and need some help on the consumption of gas it uses. The following link shows the model I have and the amount of gas it says it consumes.

www_dot_tortilladoras_dot_com

Well this model says it consumes 3 Kilos of gas. The Gas meter that I bought measures in cubic meters and the gas company sells me the gas in liters.

What I need to find out is how many kilos of gas my machine is realy using. So how do I do this convertion? How many kilos are in a cubic meter and how many cubic meters make a liter of LPG?

thanks

daniel