Varian 990 dCLD II, Operation Manual

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Model 990 dCLD II Component Leak Detector
2-4
2.2.1 Single Mechanical Pump Configuration
Figure 2-1 Single Pump Configuration
Note: Foreline and Cal Leak valves are under the control of the 990 dCLD II.
Table 2-3 Single Mechanical Pump System Valve Sequence
State Vent
Valve
Rough
Valve
Test
Valve
Remarks
Pre-Vented Closed Closed Closed The Pre-Vented state allows time to ensure that all valves
are closed before any open. The time spent in the
pre-vented state depends on valve actuation time.
Vented Opened Closed Opened The Vented state places the fixture at atmosphere. The
Test Valve keeps the turbo backed.
Pre-Roughing Closed Closed Closed The Pre-Roughing state allows time to ensure that all
valves are closed before any open. The time spent in the
pre-roughing state depends on valve actuation time.
Roughing Closed Opened Closed The Roughing state brings the fixture to vacuum. The
turbo is not being pumped. The maximum time here is
approximately 3 minutes.
Test Closed Opened Opened The Test Valve re-opens at the appropriate foreline
pressure, backing the turbo and exposing the fixture to
the foreline.
Primary
Pump
Sp
e
c
Tu
rb
o
Cal Le
ak
Cal
Leak
Foreline
Turbo Spec Tube Assembly
Test
Valve
Rough Valve
Vent Valve
Fixture
Length is Proportional
Keep Distance as Short as Possible
(in box)
Tu
be
to Sensitivity