Device and method for detecting leakage of high pressure pr tracer gas in a test piece.

According to the invention, the test piece (1) is carried vis-a-vis depression from the outside atmosphere by a leak detection device (2) having a primary pump (5) and a pressure gauge (10 ) responsive to the thermal exchange coefficients of the gases present in the atmosphere inside the test piece (1). The gas pressure gauge (10) provides a pressure-measurement signal which varies significantly depending on the nature of the gases. This variation is analyzed by signal processing means (11) producing a leak detection signal if any.