Advertisement
The Detector
The collimated radiation beam goes through the pipe and process material
where it is attenuated by the slurry. The attenuation is dependent on the
bulk density of the process material. The attenuated beam reaches the
detector on the other side of the pipe where it is measured.
The detector is made of an ion-chamber sensitive to gamma radiation. The
chamber is a small tank filled with pressurized gas. A high voltage is
supplied between the wall of the chamber and a central isolated electrode.
The interaction of the gas and the gamma rays ionizes the gas whose charge
is collected at the central electrode. The output of the ion chamber is
therefore a very small current (picoamp = 10
amp) proportional to the
-12
radiation that reaches it. That current is amplified by the detector
electronics to a measurable voltage in the range of 0–10 Vdc. This output
voltage is sent to the transmitter for processing.
The Transmitter
The SGD-O transmitter is a microprocessor-based system that processes
the signal from the detector (0–10 Vdc) to provide an output signal (4–20
mA) representing the amount of solids (proppant) added per volume unit
of carrier and/or the bulk density of the slurry. It monitors system
performance and generates system fault and warning alarms as well.
The integral keypad on the transmitter is normally used as the primary
means of communication with the instrument. Menu selections,
commands, and parameter values are entered using the keypad. The
transmitter has a four-line display that shows either one menu item or up
to eight readouts in alternation (four at a time).
An RS232 serial port can also be used to communicate with the instrument
using a PC with terminal emulation software.
SGD-O User Guide
Thermo Fisher Scientific
Advertisement
