Brooks Instrument XacTorr CMX160 - Manual (Page 11)

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they can deposit onto the diaphragm. This shield also protects the diaphragm
from thermal radiation.
4. Brooks uses a Guard Volume, which is an annular vacuum surrounding the
sensor. This acts as a thermal insulator shielding the sensor from ambient
temperature variations and also as a “trash collector” for condensable and
deposited process residual matter.
5. Electrodes can behave as antennae for RF radiation and strong magnetic
fields. Brooks places Electrode Guards on the electrodes as protection
against these interferences.
6. Ruby Rollers have been added to reduce the frictional forces, thermal
expansion stress and vibration effects on the measurement electrode which
can cause shifts and distortions in the indicated pressure readings.
7. Brooks creates a consistent stable thermal environment for the sensor by use
of heaters. This increases stability (especially in lower ranges), reduces
condensation on sensing diaphragm through heating the sensor to a slightly
greater temperature than the process. When using a heated manometer,
Brooks recommends use of an isolation valve to prevent loss of heat when the
chamber (and thus the manometer) is vented to atmosphere.
2.4 DESIGN OVERVIEW
Brooks CMXs are typically used in conjunction with pressure controllers (such
as the Brooks’s ACX and Intellisys™ Series) or digital displays to display the
measured pressure. The use of heated CMX may require a power supply
booster to provide the additional power necessary to operate the heater.
Figure 3 shows a typical configuration using the Brooks CMX.
Figure 3: Typical System
2.0
_DESCRIPTION