Case study on the non-linear behavior of the NIS-50 MPa pressure balance

The pressure balance is considered one of the most accurate methods for calibration pressure sensing devices. This method depends on two main parameters; the applied force on the piston and the effective cross-section area for piston–cylinder assembly. However, the cross-section area must be defined accurately to guarantee producing exact pressure value. In the National Institute of Standards (NIS-Egypt), the performance of the oil pressure balance (NIS-50MPa) is redefined through three models to get the most accurate one. Model (1) and (2) are commonly used to deal with a linear and a quadratic function respectively, which consequently produce a high error in our case. Model (3) is also applied to deal with a non-linear behavior (Banana shape). The results of the model (3) agreed with experimental data, which is less than 3 ppm compared with 55 and 30 ppm for other models respectively. •The non-linear behavior of pressure balance has been presented.•Three methods of performance evaluation of pressure balance has been studied.•Model 3 beat the other two models which were the standard procedures.•Model 3 can be applied for any curve fitted data that having banana shape.