SU715970A1 - Density sensor - Google Patents

Description

(54) DENSITY SENSOR

The invention relates to the field of research of liquids and is intended to measure the density of liquid media and can be used in automatic monitoring and control systems in the chemical, food, pharmaceutical and other industries.

Known vibroresonant densitometer with a vibrator made in the form of a dual tuning fork, formed by tubes with controlled liquid.

The main disadvantage of this densitometer is the poor dynamic balancing in all planes and, therefore, they are sensitive to shocks and vibrations. Even with a high Q factor of the sensor under conditions. external vibration, it can not provide the desired feeling spruce measurement accuracy 1.

A well-known immersion ring tuning fork is composed of two coaxially arranged ring elements connected by tuning forks with base 2.

The disadvantage of this tuning fork is the max measurement accuracy.

The purpose of the invention is to improve the measurement accuracy.

The goal is achieved by the fact that in the proposed density sensor the ring elements are made in the form of hollow tubes connected through hollow tuning forks to the inlet and outlet nozzles.

When measuring fluid density

0 changes the mass of the oscillating system, which leads to a change in the resonant frequency of oscillations of the annular tuning fork due to a change in the moment of inertia of the cross section

5 of the system with respect to the main axis perpendicular to the plane of the rings. Based on the known relationship for the resonant frequency of the ring tuning fork, it can be argued that the resonant frequency is proportional to the square root of the density of the liquid under study.

L.

25

 2P

where is e

the modulus of elasticity of the ring material; o - density of the ring material;

715970 3 - moment of the cross section of the system cross section; A is constant; harmonicus of the centerline of the ring is the order of the harmonic of the ring's own chabtot; yckopeHHe free pad none. Since w- „a, J, dm (2 Г 9 where dm is the mass element of the ring; dv is the volume element of the ring; dvet is the volume element of the liquid | ((- specific gravity of the liquid; - specific gravity of the material / v ..-- - then ...

FIG. 1 depicts a suggestion with an ihemechtel scheme; in fig. 2 - the same section.

The sensor contains D1VA of the ring element 1, hollow tuning forks 2, the bottom of the kit is attached to the ring elements 1, and the base is attached to the device 3 forever and the liquid outlet.

The input and output device 3 contains a cylindrical body 4, inside which there is a common pipe 5 that connects the tuning forks B and 7 to the tube .8 supplying fluid to the sensor. Two holes 9 / are made in the body 4. The tuning forks 10 and U (Fig. 1) communicate “5 with ringed elements. When feeding zkidkos in the pipe 8, they enter through the chamber b and 7, fill the cavity of the rings 1 and through the tuning forks

Claims (2)

1. Author's certificate of the USSR 486247, cl. G 01 N 9/32, 1974. 2. Milokhin N.T. Frequency Sensors of Autocontrol and Control Systems Energy 7 1968, p. 80-81. 10 and 11 merge through the openings 9 into the housing 4. When the frequency sensor is in operation, the branches of the tuning fork 7 are driven into oscillatory motion by means of the exciter 12, the signal to which is received from the oscillation receiver 13 through the amplifier 14 (Fig. 1). Thus, a self-oscillating mode of operation of the frequency sensor, in which the resonant frequency of the oscillations is a function of the density of the liquid, is provided. The quality factor of the sensor can reach several tens of thousands of hours, which ensures high sensitivity and accuracy of the density measurements made. In addition, the design of the sensor with high noise immunity can provide sufficient (0.1-0.05%) accuracy of the density measurement.