In order to ensure the reliability of measuring instruments, they must be calibrated regularly. The requirements for this are varied, depending on the respective permissible and acceptable tolerance values. The highest precision for the calibration of pressure measuring instruments is achieved using a pressure balance (dead-weight tester).
To generate the precise test pressure using a pressure balance, mass discs are placed on a defined piston surface. In order to know which masses must be placed for which pressure, a calculation must be carried out. The CPB-CAL app computes the reference pressure for the specified masses, or alternatively, the reference masses for the specified pressure.
This mass, together with the weight force, provides the defined force that acts on the surface of the piston-cylinder system. So the accuracy of the generated pressure value depends on the surface and the force acting upon it. For greater precision, disturbances influencing the surface and the force must be taken into consideration. These include the ambient temperature, the atmospheric pressure, the relative humidity and also the piston temperature. These variables can be automatically determined with the products in the CPU6000 series from WIKA. The iPad can read these measured values via Bluetooth 4.0 technology and use them for the calculation. The data and coefficients of a pressure balance can be imported using an XML file, as well as being entered manually.
With the CPB-CAL app, one gets a completely mobile computer for the operation of several pressure balances.