What is the Kn factor?
All piston-cylinder units and masses which can be mounted on Desgranges & Huot pressure balances are built around a nominal mass-to-pressure conversion coefficient, Kn. The nominal effective area of each piston-cylinder size is such that, under standard conditions, a piston loaded with 1 kg of mass will generate a pressure equivalent to the Kn value. All mass values, including the mass of the piston and of themass loading bell are adjusted to be a whole number or a fraction of a kilogram. The nominal pressure defined for a pressure balance is calculated as Kn multiplied by the mass loaded in kg. Corrections are applied to Kn to calculate the pressure defined within the accuracy tolerance of the piston-cylinder assembly used. The use of Kn and whole-number masses in no way affects the traditional pressure equation nor the factors that affect a pressure measurement made with a pressure balance. Kn is the basis of a coherent relationship between mass, effective area and pressure throughout the Desgranges & Huot pressure balance series. It is intended to be a tool that reduces operator confusion and errors by simplifying the calculation of mass loads and measured pressures.