RU1800315C - Method for determining liquid viscosity - Google Patents

Abstract

Purpose: the invention relates to the field of vibrational viscometry and can be used to control the viscosity of damping liquids at a constant temperature. SUMMARY OF THE INVENTION: a viscometer blade is immersed in a test liquid and its vibrations are excited at the resonant frequency of the suspension system. The vibration amplitude is measured and the viscosity is calculated. The viscometer constant is pre-determined. The blade oscillation amplitudes are measured at low excitation frequencies. 1 ill.

Description

The invention relates to the field of vibrational viscometry and can be used to control the viscosity of damping liquids at normal temperature.

The invention is aimed at simplifying the method for controlling the viscosity of damping liquids.

 This is achieved by the fact that in the method for determining the viscosity of a fluid, including immersing a viscometer blade in the test fluid, exciting its vibrations at the resonant frequency of the suspension system, measuring the vibration amplitude and calculating the fluid viscosity, the viscometer constant is previously determined from a control damping fluid with a known viscosity at two different temperatures, with the degree of acceleration of the blade in the control fluid being greater than unity, the amplitude of the vibrations of the blade at low excitation frequencies is measured The sedimentation rate and, based on it, are used to calculate the degree of sedation by which viscosity is judged.

The method is carried out using the device shown in the drawing.

The device consists of a viscometer 1, the excitation winding of which is a power coil 2 is connected to the output of an alternating voltage generator 3, e.g. The signal about the amplitude of oscillations of the viscometer element of the blade 6 is proportional to the output voltage generated by the measuring winding 7. The voltage from the measuring coil is recorded by a voltmeter 8, the output of which is connected to the computer 5 through the interface board 9. The blade 6 of the viscometer is connected to the spring 10 of the viscometer by two constant Magnetoo 11 and 12 cylindrical, screwed together.

The viscometer oscillation system is connected to the base 13 of the viscometer by means of a nut 14. For the viscosity of the liquid, the blade 6 of the viscometer is frozen

With

with

00

oh oh

Cj

ate

immersed in the test liquid 15. According to the program embedded in the computer, the suspension of the viscometer is sequentially excited by the generator 3 at two frequencies: zero, for example 16 Hz, and a frequency equal to the resonant frequency of the suspension. At the indicated frequencies, the output signals of the coil 7 are measured, by which, using the constant of the device, the viscosity of the liquid is determined.

The determination of a constant viscometer (calibration) is carried out as follows.

The viscometer blade 6 is immersed in a control fluid with a known viscosity, e.g. polymethylsiloxane GOST 12032-77. The liquid is selected with a viscosity such that at normal temperature (20 ° C) the degree of calm of the suspension of the viscometer is not more than 1, for example 1 and 2. Then, the actual degree of calm at normal temperature is determined by the ratio

Ё 1. x (0)

5 T X (s) o)

where x (0), x (w0) are the suspension bias amplitudes at zero and resonance frequencies, respectively.

Then, the control liquid is heated to a temperature equal to, for example, 40 ° C, and the soothing degree of the suspension of the viscometer Јi Ј (T 1) is again determined, and then the temperature of the liquid is determined at which the degree of calm is equal to unity by the ratio

TKp T0 + (To-Ti) J-go

Јi-Јo

where Ј0, Ј 1 is the degree of calming of the suspension of the viscometer at the temperature of the control liquid T0 (normal) and Tm (increased), respectively.

Then, the viscosity of the liquid corresponding to the found temperature is found from the temperature dependence of the viscosity of the control liquid, and the obtained values of the viscosity of a constant viscometer are accepted.

To measure the viscosity of the test fluid, use the ratio

/ C km Ј.

where / cr. - constant viscometer;

Ј - the degree of calming the oscillation of the suspension of the viscometer in the test fluid.

Example. The resonance suspension frequency of the viscometer is 139 Hz. Polymethylsiloxane GOST 12032-77 PMS-100 was selected as a control liquid. Liquid temperature obtained by measuring at unit

the degree of calming of the suspension of the viscometer is 25 ° C. According to the temperature dependence of the viscosity of the liquid for PMS-100 at a temperature of 25 ° C, we have a viscosity of 97 mm2 / s. The data are borrowed from GOST 13032-67. Linear interpolation in determining critical viscosity - constant viscometer

rj-rjp T -To Щ -rjo T 1 -To

25

at two temperature levels

about 150mm2 / s, That 0 ° С, / 1 45mm2 / s, Ti 50 ° C,

gives the value

  (25-o) 97.5mm2 / s.

the interpolation error does not exceed 100% 0.5%.

The positive effect of the proposed solution is to simplify the method for controlling the viscosity of damping liquids used in measuring instruments.

Claims (1)

SUMMARY OF THE INVENTION A method for determining the viscosity of a fluid, comprising immersing a viscometer blade in a test fluid, exciting its vibrations at the resonant frequency of the suspension system, measuring the amplitude of the vibrations and calculating the fluid viscosity, characterized in that to simplify the method for controlling the viscosity of damping liquids, the viscometer constant is preliminarily determined from the control damping fluid with a known viscosity at two different temperatures, moreover, the degree of calm of the blade in the control fluid is greater than unity, the amplitude of the oscillations of the blade at low excitation frequencies is measured, and the degree of calm by which the viscosity is measured is calculated based on it.