Varian 990 dCLD II, Operation Manual

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Model 990 dCLD II Component Leak Detector
2-2
2.2 Common Configurations
The 990 dCLD II is available with your choice of three pumps:
❑
V70 Turbomolecular Pump
❑
V70D MacroTorr
®
Turbomolecular Pump
❑
V70LP MacroTorr
®
Turbomolecular Pump
Table 2-1 lists operating information about the three pumps and compares advantages and
limitations relating to sensitivity and clean up time.
* Total helium pumping speed is affected by backing pump.
Table 2-1 V70, V70D and V70LP Turbomolecular Pump Comparison
Speed
Helium
Pumpin
g
Speed
Range of
Leak Rate
Minimum
Detectabl
e Leak
Maximum
Foreline
Pressure Advantages Limitations
(L/sec)* (atm cc/sec) (Torr)
V70 Turbomolecular Pump
Slow 60 10
−
9
to 10
−
6
2 x 10
−
10
0.1
Provides the highest
sensitivity of the three
pumps. Has the slowest clean
up time of the three
pumps.
Fast 60 10
−
8
to 10
−
5
2 x 10
−
9
0.1
Provides faster clean
up than V70 in Slow
speed, with slight loss
in sensitivity. Requires low foreline
pressure.
V70D MacroTorr Turbomolecular Pump
Slow 30 10
−
8
to 10
−
5
2 x 10
−
9
1.0
Provides higher
foreline pressure than
V70 in Fast speed. Provides less
sensitivity than the
V70.
Fast 30 10
−
7
to 10
−
4
2 x 10
−
8
5.0
Provides faster clean
up than V70D in Slow
speed and V70 in
either speed. Provides less
sensitivity than the
V70.
V70LP MacroTorr Turbomolecular Pump
Slow 60 10
−
7
to 10
−
4
2 x 10
−
8
5.0
Provides the fastest
clean up for the
sensitivity. Sensitivity is low, and
is lower than the V70
or V70D.
Fast 60 10
−
6
to 10
−
3
2 x 10
−
7
10
Provides the highest
foreline pressure and
the fastest clean up
time of all three
pumps. Sensitivity is the
lowest in fast mode of
all three pumps.