Varian 979 Series, Operation Manual

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Model 979 Series Helium Mass Spectrometer Leak Detector
2-20
DRAFT 9/15/03
2.6.4.2 Inputting the Rough Pump and Forepump Sizes
The next two toggle boxes are used to select the ROUGH PUMP SIZE and the FORE PUMP
SIZE on dual mechanical pump systems.
❑
Touch the ROUGH PUMP SIZE box to select either 400 LPM or 600 LPM.
❑
Touch the FORE PUMP SIZE box to select 300 LPM or 600 LPM.
It is important to set these values correctly when the 979 is configured for split-flow testing.
This allows for direct readings of leak rate.
2.6.4.3 VENT LOCK Function
Turning the VENT LOCK function ON disables the VENT button. This ensures that a user
does not vent a system unintentionally. The function status remains unchanged after a
system power down. The VENT LOCK function is inactive when the AUTO SEQUENCER
feature is enabled.
❑
Touch the VENT LOCK box to toggle the status to ON or OFF.
❑
Touch DONE to return to the previous menu screen.
2.6.5 Leak Rate Ranging Set-Up
Touch the LEAK RATE RANGING SET-UP box to display the Leak Rate Ranging Set-Up
screen (Figure 2-12). From this screen, set up and enable the RANGE STOP and MANUAL
RANGE functions and select USE FINE TEST or GROSS TEST ONLY.
Figure 2-12 Leak Rate Ranging Set-Up Screen
DONE
LEAK RATE RANGING SET-UP
BACK
LEAK RATE
OUTPUT
CAL
TRANSFER
LEAK
SET-UP
REJECT &
AUDIO SET
POINTS
AUTO
SEQUENCER
SET-UP
RANGING
SET-UP
CONTROL
SET-UP
NEXT
POINTS
SET-UP
ROUGH
PUMP
SET-UP
ESC
DN
UP
NXT
RANGE
STOP
10-XX
MANUAL
STOP
10-XX
OFF OFF
USE
FINE
TEST
OK
VENT LOCK OFF