Abstract: A vacuum pump unit including a secondary pump sub-assembly (6) rotated by an electric motor M2 and applying suction to a chamber to be evacuated (1), and a primary pump sub-assembly (2) rotated by an electric motor M1 and whose suction is connected to the output of the secondary pump sub-assembly (6), the unit being characterized in that it includes an electronic control circuit (7) for controlling the speed of rotation of the electric motor M1 as a function of to the current I2 drawn by the electric motor M2.

Abstract: A device detects leaks in a test object (1), which is contained in a test container (2). The device includes a mass spectrometer (14) detecting a noble gas such as helium, and a pump arrangement containing a primary vacuum pump (13) and a spiromolecular pump (11). The noble gas atoms flow through the latter in opposition to the pump direction towards the mass spectrometer. Between the test container (2) and an outlet port (10) of the spiromolecular pump (11), an accumulation chamber (8) is inserted, whose volume is considerably larger than that of the test container (2). The test container is provided with a source of purge gas (3) and a valve (4) for purging the test container with a purge gas under an adjustable overpressure. Closure valve (7) is disposed between the test container (2) and the accumulation chamber (8) and a closure valve (9) between the accumulation chamber (8) and the outlet port (10) of the spiromolecular pump (11).