Inficon 550-520, Translation Of The Original Operating Instructions

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Minimum detectable leak rate
The minimum detectable leak rate that can be detected by the leak detector under
ideal conditions.
MASSIVE
After selecting the vacuum range "MASSIVE" gross leaks can now be measured from
atmospheric pressure.
ULTRA
ULTRA designates the connection to the turbo molecular pump for the measurement
range with the highest sensitivity at low inlet pressures.
ULTRATEST™ sensor-technology
Highly sensitive mass spectrometer for atomic masses 2, 3 and 4.
Background signal
Helium or hydrogen (as part of water) are natural components of air.
Operation mode "Vacuum": Before any leak detection, a certain amount of the
adjusted tracer gas is already in the volume on the surfaces of the test chamber,
supply lines, and even in the leak detector itself. This certain amount of tracer gas
generates a measurement signal which is called the "Background signal". The
ongoing evacuation of the test chamber continuously reduces this background signal.
Operation mode "Sniffing": Ambient air is continuously fed into the leak detector via
the sniffer line. The amount of helium or hydrogen occurring naturally in air creates a
constant background signal.
Foreline pressure
Pressure of the backing pressure between the turbo molecular pump and the backing
pump.
ZERO
There is helium that is weakly bound to the surfaces of a specimen as a natural part of
the ambient air and is pumped bit by bit into the measurement system of the leak
detector. It produces a slowly decreasing measurement signal.
If you want to hide this background signal or the display of existing leaks, then use the
ZERO function.