Model 979 Series Helium Mass Spectrometer Leak Detector
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DRAFT 9/15/03
Appendix A. Rear Panel Interface Connectors ...............................................................................A-1
A.1 Optically Isolated Outputs....................................................................................................A-1
A.2 Optically Isolated Inputs ......................................................................................................A-3
A.3 Non-Isolated Serial and Analog Interfaces ..........................................................................A-4
A.4 Remote Control Connector..................................................................................................A-5
Appendix B. Communications Protocol ..........................................................................................B-1
B.1 Protocol (RS-232)................................................................................................................B-1
B.2 Communicating with RS-232 ...............................................................................................B-2
B.2.1 Windows HyperTerminal Set-Up Instructions ............................................................B-2
B.2.2 Printing with HyperTerminal ......................................................................................B-4
Appendix C. Introduction to Leak Detection ...................................................................................C-1
C.1 Leak Testing—Why is it Needed? .......................................................................................C-1
C.2 Classes of Leak Detection...................................................................................................C-1
C.3 Terminology.........................................................................................................................C-2
C.4 Various Methods of Testing for Leaks.................................................................................C-3
C.5 Helium Mass Spectrometer Leak Detection (MSLD)...........................................................C-4
C.5.1 Principles of Mass Spectrometry ...............................................................................C-4
C.5.2 Application as a Leak Detector ..................................................................................C-4
C.5.3 The Nature of Flow in a Vacuum ...............................................................................C-4
C.5.4 Facts About Leak Rates ............................................................................................C-5
C.6 Leak Detection Methods......................................................................................................C-5
C.6.1 Test Piece Evacuated (Figure C-1a and Figure C-1b) ..............................................C-6
C.6.2 Test Piece Pressurized (Figure C-2) .........................................................................C-6
C.6.3 Test Piece Already Sealed (Figure C-3) ....................................................................C-7
C.7 Mass Spectrometer Leak Detector—Simplified Description................................................C-8
Index ................................................................................................................................................. I-1
Summary of Contents for 979 Series
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