7
4.
Handling Precautions
Prior to use, read the safety warnings on pages I through IV and implement all necessary protective
measures for safety. Read this information together with the instruction manual for the SH2
multi-ionization gauge.
Safety warnings that you should pay particular attention to are listed in this chapter.
4.1.
Precautions related to the usage environment
Do not connect this unit in a location where the gauge head's internal pressure
exceeds atmospheric pressure. It may pose a hazard to its surroundings, including
to people, if the gauge head is damaged or it flies off its connector. When
exceeding atmospheric pressure, install an isolation valve to ensure that the
gauge head's internal pressure does not exceed atmospheric pressure.
Excessive vacuum chamber pressure
If this unit is exposed to chemically active gases including corrosive gases and
halogen or halogenated gases, problems will occur such as filament breaks or
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 as much as
possible.
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 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 as much
as possible by using this unit with the isolation valve closed.
Use in a CVD gas atmosphere
The ambient temperature of the gauge head affects the measured value due to
the measurement principle of the Pirani vacuum gauge. Be careful with the
attachment location so the ambient temperature does not dramatically deviate
from the temperature during calibration (approx. 25°C).
Temperature fluctuations
4.2.
Precautions related to usage
・
Secure cables as much as possible so that force is not applied to cable connectors.
・
Firmly insert the RJ-45 connector.
・
To perform accurate pressure measurements, allow the pressure sensor to age for 20 minutes or
longer before measuring.
4.3.
Attaching this unit
4.3.1.
This unit attachment environment
Always connect this unit electrically to a grounded vacuum chamber. Use a
conductive metal clamp on the NW flange. If this unit is not correctly connected,
it will not only show the wrong pressure, there is a risk of damage to this unit
and the equipment connected to this unit and a risk of fire.
Protective grounding
When isolated with the vacuum chamber, ground the NW flange metal clamp
section with a class D (class 3) ground.
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 of overpressurization when using gases other than nitrogen.
Gas type dependency
The pressure measurement measures the static pressure at the location where
the gauge head is connected. Take care to attach this unit in a location that is
unaffected by gas flows and emitted gas in the measurement system.
Gas flow in the measurement system
