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Installation and Configuration Manual 3
Introduction
Installation (Short Stem) Electrical ConnectionsInstallation (Long Stem)Introduction
1.2.3 What is it used for?
The 7827 meter is ideally suited to applications where continuous real time measurement of viscosity
is required. The meter is particularly suited where viscosity is an indication of the behavioral
properties of the fluid, for example in applications involving spraying, coating or dipping.
Some uses are in the oil and petrochemical industry for:
•Refining
•Marine
•Power
• Heavy fuel oil (HFO) blending and bunkering
1.3 Principle of operation
The 7827 meter operates on the vibrating element principle, the element in this case being a slender
tuning fork structure which is immersed in the liquid being measured.
The tuning fork is excited into oscillation by a piezo-electric crystal internally secured at the root of
one tine, while the frequency of oscillation is detected by a second piezo-electric crystal secured at the
root of the other tine. The sensor is maintained at its first natural resonant frequency, as modified by
the surrounding fluid, by an amplifier circuit located in the electronics housing.
The electronics circuit actually excites the sensor into oscillation alternately at two positions on the
frequency response curve as shown in Figure 1-1. In doing this, the quality factor (Q) of the resonator
may be determined as well as the resonant frequency.
For details of the viscosity and density calculations, see the Calculated Parameters appendix.
Figure 1-1 Frequency response curve showing the quality factor (Q) calculation
0dB level
-3dB level
Frequency
Response
τ
B
τ
A
A
B