Brooks Instrument CMC Series - Manual (Page 12)

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3.1 Operating Specifications
3.2 Checking and Zero Adjustment
After installation on a system, the CMC Series may require initial Zero adjust-
ment. Figure 1 and Figure 2 show the location of the Zero adjustment potentiom-
eter. Use a digital voltmeter to view the signal output of the CMC Series. Adjust
the signal output of the CMC Series to be the gauge resolution specification.
Make this adjustment at a pressure at least one half decade below the CMC
Series’s resolution. For example, for a 10 Torr FS unit, the zero pressure should
be less that 5 X 10
-4
Torr. For a 1000 Torr unit, a pressure less than 0.050 Torr is
sufficient. The Zero potentiometer is a multi-turn potentiometer providing very
fine adjustment of the zero over a +/-250 mV range.
3.3 Span (Full Scale) Adjustment and Calibration
The Zero adjustment is the only adjustment that should be made in the field.
Span (Full Scale) adjustments require a calibrated and certified reference stan-
dard and should only be attempted by qualified personnel. Return the CMC
Series to Brooks for periodic calibration, Span (Full Scale) Adjustment and Cali-
bration adjustments, and servicing.
3.4 Calibration Services
Brooks maintains a complete calibration facility that is traceable to the National
Institute of Standards & Technology (NIST). If the device needs recalibration or
recertification, call Brooks Technical Support.
Full Scale Ranges 10, 20, 100, 200, and 1000 Torr
Performance
Accuracy 1 0.5% of Reading
Resolution 2 0.01% of Full Scale
Temperature Affect to Zero 0.005% Full Scale/Degree C
Temperature Affect to Span 0.027% Full Scale/Degree C
Response Time 20 msec
Mechanical
Exposed Materials 3
Inconel ®
Over-pressure Limit 45 psia
Weight 0.3 lbs (137 grams)
Electrical
Input Power 12 to 30 VDC
Output Signal 0-10 VDC, (<10K ohm load)
Power Consumption <200 mW
Electrical Connectors
5-Pin Terminal Strip
9-Pin D-Sub
15-Pin D-Sub with 6 Inch Cable
Certifications
Electromagnetic Compatibility Fully CE Certified to EMC Directive 89/336/EEC
1 RSS-including hysteresis, linearity and non-repeatability. Optional higher accuracy spec - 0.25% of
reading.
2 0.03% for 10/20 Torr
3 Wetted material is for 1/2” tube stub option, other flanges and fittings will add stainless steel.
3.0
_OPERATION