Thermo Scientific DensityPRO NAI Series, User Manual

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Thermo Scientific DensityPRO User Manual C-1
Appendix C
Density Calculation
Basic Density
Calculation
The basic density calculation converts the measured intensity of the radiation to a
density value. This calculation is the basis for all of the various density calculations
used in the gauge. The terms used to calculate density consist of constants, user entered
values, measured values, and calculated values.
– Constants – These terms are fixed values that the user may be able to read.

G: Geometry factor (0.85) – The geometry factor does not have any units. It is
used to correct for the location of the source relative to the detector with
different source heads and mounting configurations. History has determined
that this value can be a constant.
– User Inputs – These are values entered by the user. The user shall be able to read
and write the value for the items in this section.

L: Pipe ID – The inside diameter of pipe in centimeters (cm). The default
value is 0 cm.

Dc: Density of the carrier – The density of the carrier fluid in grams per cubic
centimeter (g/cm3). The default value is 1 g/cm3.

µc: Attenuation Coefficient of the carrier – The attenuation coefficient of the
carrier fluid in square centimeters per gram (cm2/g). The default value is
0.086 cm2/g.

Ds: Density of the solid – The density of the solid material in grams per cubic
centimeter (g/cm3). The default value is 2.65 g/cm3.

µs: Attenuation Coefficient of the solid – The attenuation coefficient of the
solid material in square centimeters per gram (cm2/g). The default value is
0.077 cm2/g.

Ibkg: Background radiation – The radiation measured at the detector with the
shutter on the source closed in counts per second (cps). The default value is 3
cps.
The background radiation is determined by measuring the radiation intensity
at the detector with the shutter closed and using the following equation.
Ibkg (cps) = Measured Radiation Intensity (mr/hr) x 300 (cps/(mr/hr))

Dcal1: Density for calibration point 1 – The density of the process material in
grams per cubic centimeters (g/cm3) during calibration. The default value is 0
g/cm3.