| 摘要 |
<p>The leak detector comprises a detector head which is to be scanned across a surface to detect a signal gas emanating from the surface, the opposite side of which is supplied with a signal gas under pressure so that signal gas passes through leaks in the surface. A curtain of barrier gas is provided from a circular channel (20) around a sample inlet (2) to protect the inlet from spurious signal gas. - Orifices (36) between the inlet and the curtain provide narrow high velocity jets (38) which impinge on the surface (S) within curtain and break up jets of signal gas which might otherwise flow along the surface and escape under the curtain without allowing the signal gas to reach the sample inlet. Pref. the orifices are arranged to provide flow parallel to the axis of the detector head. However, the orifices may be inclined to the axis of the detector head. Pref. the orifices are spaced out in a ring and lie adjacent to the curtain. (1/1) USAB- US4577490 A A detector head is 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 gas under pressure so that the gas passes through leaks in the surface. Detection of gas by the head then constitutes detection of a leak. - A curtain (1) of barrier gas is provided around a sample inlet (2) to protect the inlet from spurious gas. Orifices (36) provide narrow high velocity jets (38) which impinge on the surface (S) within the curtain and break up jets (34) of gas which escape under the curtain without allowing the gas to reach the sample inlet. (4pp)</p> |
