MKS HPS 937A Series, Руководство по эксплуатации и техническому обслуживанию владельца, Страница: 94 / 108

937A Multi-Sensor System
A.15
Cleaning the Series 317 Sensor
Roughing pump oils and other fluids condensing or decomposing on the
heated filament can contaminate the Sensor. This changes the emissivity of
the filament, which in turn can cause the calibration to change, especially at
low pressure.
It is not advisable to clean the Sensor. Trying to clean it may
either deform or break the filament. The deformed filament
would then cause additional error from a shift in the
Sensor's output.
Replace the Sensor if it becomes contaminated (see Spare Parts and
Accessories, page.67).
Testing the Series 317 Sensor
The most common cause of sensor failure is a broken filament. This might
be caused by physical abuse or sudden venting of the sensor to
atmosphere at the inlet port.
1 With a #1 Phillips head screwdriver, remove the two screws to
separate the connector/electronics subassembly from the end of the
Sensor as shown below.
2 Check the resistance on the Sensor's pins listed in the first column
on the table below. Test the Sensor with an ohmmeter with less than 5
mA of current. The resistance readings of a normal Sensor measured
at atmospheric pressure and at room temperature (20°C) are listed in
the middle column. If the condition shown in the right column exists,
the Sensor should be replaced.
Preparing the 317 Sensor for Bakeout
Remove the cable from the Sensor. Use a #1 Phillips head screwdriver to
remove the two screws at the end of the connector/electronics
subassembly to separate it from the Sensor. The standard Convection
Pirani Sensor can be baked up to 150°C and the Shielded Convection
Pirani Sensor can be baked up to 100°C.
Sensor Tube
Check Resistance (
Ω Ω Ω Ω Ω
) If
20
> 20 x 10 6
27
> 20 x 10 6
Higher, filament is broken or
burned out.
Lower, Sensor is damaged or
contaminated.
Higher, temperature
compensation winding is
broken.
Lower, temperature
compensation winding is
F1 to F2
F1 to Sensor port
F2 to Sensor port
TC1 to TC2
TC1 to Sensor port
TC2 to Sensor port