Abstract: A portable leak detection system. The inventive system (10) includes a portable housing (40). The housing is equipped with a pneumatic circuit including an inlet (12) for receiving fluid from a source and an outlet (36) for communicating the fluid to an external unit under test. A flow meter (30) is disposed within the housing (40) between the inlet (12) and the outlet (36) for measuring the flow of the fluid into the unit under test. A calibration verification mechanism (50) is disposed within the housing (40) for verifying the calibration of the flow meter (30). In a specific implementation, the invention further includes a pressure regulator (22) disposed within the housing (40) between the inlet mechanism (12) and the flow meter (30).