Varian 990 dCLD II, Руководство по эксплуатации

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2-1
Model 990 dCLD II Component Leak Detector
Section 2. Customer Integration
The information provided in this section assists you in making decisions to provide the
optimum level of leak detection for your operation.
2.1 Physical Considerations
The control unit of the Model 990 dCLD II is intended to be mounted in a standard 19-inch
rack enclosure. It can, however, be mounted in any orientation provided that air movement
through the unit is not impeded. For efficiency sake, mount the Model 990 dCLD II so that
the LEDs can be seen from a convenient location to determine the status of the system at a
glance.
The Optional Front Control Panel can be mounted either directly onto the face of the con-
trol unit or remotely in a standard 19-inch rack enclosure. A 10-foot cable provides connec-
tion to the front of the control unit. As is the case with the control unit, it can be mounted in
any orientation that provides unimpeded ventilation, and that allows easy viewing and
access to the displays, touch screen panel, and control buttons. Also, keep in mind that the
audio for the 990 dCLD II emanates from the rear of this panel.
The Turbo Spec Tube Assembly can be mounted in any orientation. The spectrometer tube
must be isolated from strong magnetic fields such as motors, transformers, and magnets.
Steel structures and steel objects should be should be kept at least 2 inches away from the
closest edge of the spectrometer tube. Failure to do so will result in damage to the magnet in
the spectrometer tube. During normal operation, the spectrometer tube feels quite warm. A
continuously running fan at the end of the high vacuum pump directs cooling air toward the
end of the pump.
To achieve maximum sensitivity, mount the turbo spec tube assembly as close as possible to
the test chamber or part being tested. The length and number of bends in the plumbing
between the turbo spec tube assembly and the test chamber should be less than the length
and number of bends in the plumbing between the turbo spec tube assembly and the
mechanical backing pump. Likewise, the diameter of the plumbing between the turbo spec
tube assembly and the test chamber should be the same size or larger than the diameter of
the plumbing between the mechanical backing pump and the turbo spec tube assembly.
You must also consider the type and size of the mechanical pumps for your system. For
accurate and repeatable leak testing, Varian recommends that customer-supplied roughing
and forepumps be helium-stable mechanical pumps, such as Varian oil-sealed mechanical
pumps. (See Section 2.3 “Size of Mechanical Pumps” on page 2-7.) The use of
non-helium-stable pumps will result in erratic, unreliable leak rate readings and an inability
to calibrate successfully.