Unit of measurement of fluid pressure.
The unit of pressure derived from the International System of Units (SI) is the pascal (Pa). The Pascal is the uniform pressure that exerts a total force of one newton perpendicularly upon a plane surface of one square metre.
1 bar corresponds to 100,000 Pa, or about 1 kg/cm2. Normal atmospheric pressure, for example, is around 1 bar. Gas is delivered to the end consumer (e.g. for a boiler) at 20 millibars.
Gas produced by the fermentation of animal or vegetable organic materials in the absence of oxygen. This fermentation, which is also known as methanisation, occurs naturally in swamps and spontaneously in dumps containing organic waste.