Varian 979 Series, Руководство по эксплуатации

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4-3
Model 979 Series Helium Mass Spectrometer Leak Detector
DRAFT 9/15/03
For simplicity, the maintenance functions in this section are grouped by recommended
frequency, as shown in Table 4-1, based on assumed everyday use.
These functions can be carried out at routine intervals, as indicated. The 979 must be cali-
brated to verify sensitivity at least once a day. However, other functions may be carried out
either more or less often, depending on the frequency of use.
Maintenance functions that may be required on a demand basis, such as changing an Ion
Source after filament failure, are listed in Table 4-2.
Table 4-1 Scheduled Maintenance
Description Daily 12 Months Refer to
Calibration check
X
Section 4.1 “Daily Maintenance” on
page 4-4
Recalibrate the
internal calibrated leak
X
Section 4.2 “Recalibrate the Internal
Calibrated Leak” on page 4-4
Spectrometer tube overhaul
X
Section 4.3 “Spectrometer Tube
Overhaul” on page 4-4
Table 4-2 As-Required Maintenance
Function Most Common Symptom Refer to
Spectrometer tube cleaning Loss of sensitivity, increase in
background, high ion voltage
(> 300 VDC), required to tune the leak
detector. Section 4.3 “Spectrometer
Tube Overhaul” on page 4-4
Ion source replacement Filament failure (as soon as convenient
after second filament is in use). Section 4.4 “Ion Source
Replacement Outside of
Annual Maintenance” on
page 4-20
Tuning adjustments Use of a calibrated leak in the field other
than the one tested at the factory, or if
calibration is not successful. Section 3.1.2 “Manual
Spectube Tuning” on page 3-4
Mechanical Pump
Fluid Change Persistent, high helium background
signal. Fluid contamination (dirty brown
color indicates burnt or contaminated
fluid, milky white consistency indicates
high water vapor content in fluid). Section 4.5 “Mechanical Pump”
on page 4-22
Mechanical Pump Tip Seal
Replacement Pump base pressure has risen to an
unacceptable high level for the particular
application. Section 4.5 “Mechanical Pump”
on page 4-22