Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives regarding pressure are specified in the unit bar. Though the bar is not a SI unit like the pascal, nor a cgs unit, it is accepted for use with the SI by the US National Institute of Standards and Technology. The bar is widely used in descriptions of pressure because it is only about 1.3% smaller than "standard" atmospheric pressure, and is legally recognized in countries of the European Union. Conversion between the units bar and the MPa is however easy since 10 bar = 1 MPa. If there are any contradictions between new decisions and preceding decisions adopted at
Henry's law a species in the aqueous phase, and formula_8 is the partial pressure of that species in the gas phase under equilibrium conditions. The SI unit for formula_12 is mol/(m Pa); however, often the unit M/atm is used, since formula_17 is usually expressed in M (1 M = 1 mol/dm) and formula_8 in atm (1 atm = 101325 Pa). The Henry solubility can also be expressed as the dimensionless ratio between the aqueous-phase concentration formula_17 of a species and its gas-phase concentration formula_24: For an ideal gas, the conversion is: where formula_27 is the gas constant and formula_28 is the temperature.