Both Busch TAPIR leak detectors offer three different test modes: gross, normal and high sensitivity. These modes are selected automatically. Depending on the inlet pressure detected by a Pirani pressure sensor, different valves in the valve block are automatically actuated. This causes different valves to open so that the tracer gas enters the turbomolecular vacuum pump at different positions. Depending on where the gas enters the turbomolecular vacuum pump, the sensitivity is increased. The gross mode in TAPIR HL 1102 A starts at 15 mbar, whereas the gross mode in TAPIR HL 2216 A starts at 25 mbar. Furthermore, the TAPIR HL 2216 A offers an additional mode, called massive mode. This enables qualitative leak detection starting at 100 mbar, before the normal test modes are reached.