Reference primary standards Pressure balances are high accuracy fundamental pressure standards that define the derived unit of pressure directly from the fundamental units of mass, length and time following the formula p= F/A. The direct measurement of the pressure with a balance combined to the know-how of Desgranges & Huot guarantee the best metrological specifications on the market. Functionality The CPB6000DP is designed for differential pressure calibration at high static line pressure and consists of two gas operated pressure balances integrated into one common housing. One side of a CPB6000DP can also be used as a single instrument for gauge pressure calibrations. The differential pressure is defined on a single piston-cylinder assembly. The second piston-cylinder system is used as a memory for the zero condition. The operating procedure is to apply the same static pressure to both piston-cylinder assemblies with the measuring element floating. | Tarring masses are then applied to the comparison-memory element so that both pistons are balanced in their mid position. The comparison element is then isolated and the mass equivalent to the differential pressure increment required is added to the measuring piston. The pressures on both sides are adjusted using the variable volume. This ensures a very accurate measurement of differential pressures. High accuracy The exceptional intrinsic characteristics of high quality piston-cylinder systems allow the static pressure to be set and maintained with a precision much greater than the absolute accuracy on either piston-cylinder effective area. The cross float consists of adjusting the mass load on one of the pistons until both pistons float together in equilibrium at the common static pressure. Due to the sensitivity of Desgranges & Huot’s piston-cylinder systems this equilibrium can be realized within a tolerance of 1 ppm. |
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