The present invention relates to a method for monitoring a leak detector and an associated leak detector comprising a secondary vacuum pump having a rotor, such as a turbomolecular, molecular or hybrid vacuum pump. The invention applies more particularly to the leak detectors that are capable of being moved, such as portable leak detectors, on wheels or able to be moved by trolley.
In operation, the rotor of a secondary vacuum pump rotates at a very high rotation speed, such as several thousand revolutions per minute, in order to establish a high vacuum or ultra-high vacuum. Because of the very high rotation speed and of the inertia of the rotor, the user must wait a certain time after having commanded the stopping of the secondary vacuum pump for the stopping of the rotor to be effective and for him to be able to move the leak detector without risking damaging it. Specifically, a hasty movement may cause the secondary vacuum pump to seize because of the gyroscopic effect. The movement of the leak detector generates thrust forces that can deflect the rotation axis of the rotor and cause it to seize. This risk exists even for slight movements.
In order to limit this risk, the manufacturers recommend waiting several minutes after the command to stop the vacuum pump before moving the leak detector. The recommended waiting times depend on the type of secondary vacuum pump and on the rotation speed of the rotor at the time of the stop command. They are usually between five and ten minutes. It is found however that, during use, certain users do not comply with these waiting times. This failing is mainly due to the fact that the recommended time is not the same for all the leak detectors. It is therefore not necessarily known by the user at the appropriate moment. Other effects also lead to a failure to comply with these waiting times, for example when the user has incorrectly estimated the waiting time that has elapsed or else if he has forgotten the manufacturers' recommendation.
This problem is common to all the leak detectors that are capable of being moved and that comprise a secondary vacuum pump that has a rotor.