Conception et caractérisation des fuites d’étalonnage de frigorigène

Nowadays, leak detection is widely used in many fields such as automotive and refrigeration industries. European Regulation No 517/2014 identifies leak tightness as the key point to decrease the emissions of the refrigerant gases with greenhouse effect. Tightness of systems charged with refrigerant fluids must be controlled periodically by refrigerant gas detectors. According to the Commission Regulation No 1516/2007 these detectors are required to be tested at least once per year with reference leaks, or “calibrated” leaks, to confirm a detection limit of 5 g per year. For this purpose, a technique to built reliable reference leaks made of R134a (1,1,1,2-tetrafluoroethane) is described. These leaks are suitable to fulfill the requirements of EN14624:2012 which defines the procedure to test refrigerant leak detectors. The proposed design takes advantage of the suitable permeability of vinyl methyl silicone rubber (MVQ silicone). The leak rate is adjusted by the size of a hole drilled in the reservoir cap. The described design is suitable to manufacture reference leaks having leak rates from 1 to 30 g per year. The long term stability was found to be within the calibration uncertainty of ±3% and the temperature coefficient of 3.2% per K.