Testing the tightness of a main airpipe of a train

The process involves feeding flow rate into a main air pipe by a pressure controller (1). A pressure drop is measured in the pipe over a measurement period by a pressure sensor (6). A ratio between relationship of exhausting leakage flow volume to the pipe volume and leakage volume flow is determined from a determined leakage volume flow and the measured pressure drop in the pipe with an average pressure and an air pressure. An independent claim is also included for a device for leak testing main air pipe of a train.