MKS HPS 945 Series, Operation And Maintenance Manual

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Digital Pirani Vacuum Sensor System
Using the Series 945 Pirani System with Other Gases ............ 20
Nitrogen Equivalent Pressure ................................................................. 20
Calibrating for Other Gases .................................................................... 21
Maintaining the Series 945 Pirani System ............................... 22
Troubleshooting and Service ................................................................... 22
Cleaning the Pirani Controller Front Panel .............................................. 22
Cleaning the Pirani Sensor ..................................................................... 23
Testing the Pirani Sensor ....................................................................... 23
Accessories ............................................................................. 24
Product Warranty ..................................................................... 25
Notes ....................................................................................... 26
Appendix A: How the Series 945 Pirani System Works .......... A.1
Theory of a Thermal Conductivity Sensor ............................................. A.1
Measurement Limits ............................................................................. A.1
The Series 945 Pirani System Design Overview .................................. A.2
Amplifier ........................................................................................ A.2
Output ............................................................................................ A.2
Set Point Relays ............................................................................ A.2
Comparator .................................................................................... A.2
Notes ...................................................................................... A.3