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1 OVERVIEW
The LQ300A00****** Density Meter measures the density of a substance that flows in a tank and
through a pipe by means of a phase difference method using microwaves.
This method is little affected by the presence of contamination. It uses no moving mechanical parts or
mechanism that is often used in other measuring methods for cleaning, sampling, or defoaming. It
permits continuous measurement.
The density meter, which outputs measured density in electric current, is suitable for an application in a
process for monitoring and controlling.
1.1 Principle of Measurement
This insertion type density meter LQ300A00****** has adopted a new measuring method called
"Phase difference method by microwaves." When microwaves go through a substance and comes out of
it, by measuring the phase lag of the waves, we get a certain physical property of the substance that is
proportional to the density.
The theory of density measurement based on the phase difference method is shown in Figure 1.1
The difference between the phase lagθ
phase lagθ
of the microwave received through the object substance, that is,
2
Δθ ＝ θ
− θ
2
is determined, and since the differenceΔθis in direct proportion to the density, the density of the
object substance is measured.
of the microwave received through water (density 0%) and the
1
1
Transmitted
microwaves
Substance measured
Phase difference △θ＝θ
Fig. 1.1 Principle of phase angle difference
Water
Received microwaves
with phase lag θ
１
Phase lag θ
２
−θ
２
１
14
6 F 8 A 0 7 8 7
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