SLURRY CHARACTERISTICS
The relationship between the measurement of ultrasonic attenuation and the percentage solids of a particular slurry type is dependent on the density of the slurry particles and their average size distribution. This is known from experience for most slurry types, and is expressed as a number, which is the ultrasonic attenuation in deciBels (dB), per mm gap between sensor faces, per one percent suspended solids.
The relationship between attenuation and suspended solids is shown graphically in Figure 2. Calibration of the unit involves adjustment of the zero point, by setting up the sensors in clean liquid (supernatant), and then setting the slope of the straight line graph, either according to past data or from site samples.
In the memory of the MSM400 there is information on various slurry types, to enable simple initial
Attenuation
(dB)
| e |
| p |
lo | |
S |
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Zero Ref
% Solids
Figure 2 : Ultrasonic Attenuation versus
Suspended solids
Calibration:
The Mobrey experience with using ultrasonics for suspended solids monitoring has been developed over 25 years. Calibration systems for the MSM400 use this experience, allowing the plant operator to choose whether to set up the unit based on Mobrey site and slurry experience, or whether to take site samples to fine tune that data to suit the specific site conditions. The MSM400 is versatile enough to allow simple or complex calibrations.
IP258
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