Abstract: A leak detecting apparatus includes a detector arranged for sensing a gas emanating through a specimen to be tested for leaks; a leak simulator having an outlet emitting a gas of a known flow rate; and a valve for selectively connecting the outlet to the detector during a calibration thereof and disconnecting the outlet from the detector during a leak detecting operation thereof. The valve comprises a fast-switching 3/2-way valve including a movable valve member having first and second positions. In the first position the movable valve member allows communication through the valve solely between the outlet of the leak simulator and an input of the detector and in the second position allows communication through the valve solely between the outlet of the leak simulator and the atmosphere.

Abstract: Leak detector operating according to the countercurrent principle is used in a leak detection method and includes a first high vacuum pump having an inlet which is connected to an inlet of the leak detector, a second high vacuum pump having an inlet which is connected to a mass spectrometer, and a first roughing pump having an inlet which is connected to the outlets of the first and second high vacuum pump respectively. In order, on the one hand, to detect particularly large leaks and, on the other hand, avoid overloads due to high test gas concentrations, a second roughing pump is provided having an inlet which may be selectably connected to one of the inlet of the leak detector via a conduit equipped with a control valve and to the inlet of the first roughing pump by way of a conduit equipped with a choke.