Inficon 540-200, Перевод оригинальной инструкции по эксплуатации

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5.2 Operating modes and measurement setup
NOTICE
Material damage due to loss of oil
Pumps with oil seals can lose oil and damage the unit.
► Arrange pumps with oil seal below the unit or lay the line so that no oil can get to
the unit.
The T-Guard2 can be used to measure in 3 different operating modes:
• Accumulation measurement
• Carrier gas measurement
• Continuous measurement
For accumulation measurement, the leak rate of the test object is formed from the
difference between two helium measurements. The pressurized and helium-filled test
object is placed in the measurement chamber, or it is subjected to pressure in the
measurement chamber. The first measurement is performed immediately afterwards.
If the test object leaks, the helium concentration in the measuring chamber will
increase and the following second measurement will determine this higher
concentration.
For the carrier gas measurement, the test object is also either placed, filled and ready,
in the chamber, or is subjected to pressure only after being placed in the chamber. In
any case, the measurement chamber is not airtight. Instead, a clearly defined amount
of outside air is blown into the measurement chamber. The airflow comes into contact
with the test object and carries any emerging helium from the test object to the T-
Guard2. The device measures the helium content in the gas flow for a defined period
of time and determines the leak rate from the measurement result.
The carrier gas measurement allows for larger leaks to be quickly identified. The
carrier gas measurement is, however, sensitive to variations in the helium
background. Since the helium background often varies in a production environment,
accumulation measurement is generally more reliable.
The device measures the helium background and displays the level with a message:
<10 ppm Background OK
10…18 ppm Background moderate
>18 ppm Background bad