4
Principles of Operation
The detector's raw output signal is processed through several stages of software in the X96S.
Some of the more significant stages of signal processing are:
• Units Conversion – conversion of counts into user-selected mass flow units
• Measurement Range – 4-20 mA output defined by the user-selected range in user-selected units.
• Digital Filtering – signal smoothing to reduce statistical radiation noise
• Dynamic Tracking – quick gauge response to quick process changes.
• Source Decay Compensation – automatic compensation for the radioisotope decay
• Calibration (Referencing) – calibration of gauge to user process.
The Calibration (and Referencing) procedure relates detector output (in counts) to numeric values that accurately represent the
actual process mass flow.
The mass flow algorithm (or curve) used by the X96S software is a logrithmic function. That is, the relationship between the
detector output and the process mass denisty is mathematically expressed as:
Total Mass Flow [Solids & Carrier]
fa
uTIc
Io
LnRRc ×××+= )
1
()(
0
Where:
R
o
= Reference density on water
R
c
= Current mass flow in pipe
I
o
= Detector signal on water
I
c
= Current detector signal with material in pipe
a = ID of pipe in inches
uT = Mass absorption coefficient, which for Cs-137 approximately equals 0.04 ft
2
/lb or (0.008 M
2
/kg)
Ln = Natural Log
f= Flow rate
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