10
6.
CAUTIONS IN HANDLING
The magnetic flux density at the center of the sensor head is about
0.1 T. It will be attracted by or attract a metal part nearby with high
magnetic force. Be careful in maintenance that a screwdriver or a
metal part will be attracted with high magnetic force.
Beware of magnetic field
If this unit is exposed to chemically active gases including corrosive
gases and halogen or halogenated gases, problems will occur such as
pressure characteristics changing. When using this unit in these types
of environments, install an isolation valve between this unit and the
vacuum chamber and protect this unit as much as possible so it is not
exposed to these gases.
Use in a corrosive gas atmosphere
If this unit is exposed to gases that deposit materials including CVD
(Chemical Vapor Deposition) material gases and rotary pump oil mist,
problems will occur such as pressure characteristics changing. When
using this unit in these types of environments, install an isolation
valve between this unit and the vacuum chamber and protect this unit
so it is not exposed to these gases.
Use in a CVD gas atmosphere
If there is a large quantity of fouling in the gauge head from the
gradual vaporization of moisture or organic matter, pressure accuracy
and response speed will be affected. Review installation locations and
methods so that fouling does not occur.
Moisture and fouling
The pressure value and accuracy for this unit differ by the type of
gas measured. The accuracy for this unit is based on measuring
nitrogen gas. Be careful when using gases other than nitrogen.
Gas type dependency
• Start measurement more than one minute after turning on power and the output is
stabilized.
• Do not turn off the power to the sensor head during a sequence of measurements.
• The characteristics of the sensor head may change if it is exposed to a chemically
active or highly adsorptive gas. In that event, fill the sensor head with nitrogen or
inert gas or dry air with the sensor head energized with power and pump it for
purging and repeat this step. It may be restored to the original condition. However,
do not spray such gas to the opening of the sensor head for purging. If there is no
prospect of the characteristic being restored, replace the sensor head with a new one.
• The magnetron type vacuum gauge is sensitive to all types of gas, but the sensitivity
varies with the type of gas. The unit displays pressure by assuming that the gas is air.
• This gauge uses no consumable part like hot filament, but if a high voltage is applied
for an extended time at a pressure exceeding the higher limit of measurable pressure,
the sensor head interior may be contaminated.
• Be careful about pressure when starting measurement (start discharge by turning on
HV).It is difficult to discharge in the 10-5Pa(10-7Torr) range. In case it was
impossible to discharge , keep pressure more than 10-3Pa(10-5Torr) range and turn
on HV.
• When pressure is more than measurable range, turn off HV and stop measurement.
Summary of Contents for G-Tran BMR2
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