Patent ID: 8234911

Claim:
A method for detecting a leak in a double pipe, with the double pipe having an internal pipe and an external pipe surrounding the internal pipe with a gap, which comprises the steps of: filling the gap with a medium; moving the medium in the gap in a longitudinal direction of the double pipe to a first end of the double pipe, with the medium subsequently flowing in from a second end; acquiring at the first end and at the second end, in each case a first mass flow and a second mass flow for the medium flowing into and out of the gap; investigating, at the first end, the medium for a substance which is characteristic of a leak; producing a leakage signal if the substance is detected in the medium; ascertaining a transport time of the substance from the leak to the first end as a time difference between switching on a conveying device and detection of the substance; ascertaining a point of the leak on a basis of the transport time and on a basis of the first mass flow and second mass flow of the medium; and ascertaining, in a case of the leak, a loss rate of the substance which flows through the leak on a basis of the first mass flow and the second mass flow.