Detecting leaks.

摘要

A leak detector comprises a detector head which is to be scanned across a surface to detect a signal gas eminating from the surface. The opposite side of the surface from the head is supplied with a signal gas under pressure so that signal gas passes through leaks in the surface. Detection of signal gas should then constitute detection of a leak. A curtain (1) of barrier gas is provided around an inlet (2) to protect the inlet from spurious signal gas. An annular sample inlet (42), leading to inlet (2), is arranged in conjunction with lip (41) to collect signal gas which originates in the form of a jet (35) and runs along a jet collection surface (37) to inlet 42.