RU2061215C1 - Viscometer - Google Patents

Abstract

FIELD: measurement of viscosity of liquid media. SUBSTANCE: viscometer has liquid supply system with flowmeter and slotted capillary tube formed by lateral surfaces of two coaxial horizontal cylinders. Outer cylinder is rigidly secured and inner cylinder may move in parallel relative to outer one under action of mechanical load. Viscometer is provided with meter of slotted capillary tube length which is equal to depth of submergence of inner cylinder in outer one. EFFECT: enhanced reliability. 1 dwg

Description

 The invention relates to techniques for determining the viscosity of liquids under shear and can find application in chemical, oil refining and other industries where it is necessary to measure the viscosity of liquids in a wide range with high accuracy.

 A known design of a cargo capillary viscometer [1] in which the liquid is expelled from the chamber through the capillary under the action of a piston, to which a load is applied, which can vary. The movement of the piston is fixed by the indicator.

 The disadvantage of this viscometer is the need to use capillaries of various flow areas for liquids of various viscosities.

 Closest to the proposed is the design of the viscometer [2] containing a slotted capillary, a fluid supply system and a flow meter device in which the capillary is made in the form of a radial annular gap formed by two cylinders mounted on one axis, one of which is rigidly fixed, and the second is made with the ability to move along the axis under the action of the load.

 The aim of the invention is the creation of a viscometer design that provides high measurement accuracy when changing in a wide viscosity range of the studied liquids.

 The technical result is the creation of a viscometer design having a capillary of annular cross-section, the length of which can automatically change depending on the viscosity of the test fluid, which allows to increase the measurement accuracy in a wide range of viscosity changes.

 The goal is achieved in that in a viscometer containing a slotted capillary, a fluid supply system and a flow meter, the capillary is made in the form of an annular slit formed by the side surfaces of two cylinders concentrically mounted on a common horizontal axis, with which the inner cylinder can move parallel to the outer under the influence of the gravity of the load and the forces acting on it the flow of the investigated fluid, and the outer hollow cylinder is rigidly fixed in a horizontal position.

 The drawing shows the device viscometer of the proposed design.

 The viscometer consists of an outer 1 and an inner 2 cylinders concentrically mounted on a common horizontal axis 3. The outer and inner cylinders form a chamber 4, into which the test liquid is fed under pressure through a flow meter 5. The lateral surfaces of the cylinders form a slit capillary 6 of annular cross section through which liquid flows from the chamber 4. The outer hollow cylinder 1 is rigidly fixed in a horizontal position. The inner cylinder 2 can move together with the axis 3 parallel to the outer under the influence of gravity of the load 7 and the forces acting on it the flow of the studied fluid. The length of the capillary 6 varies depending on the movement of the inner cylinder relative to the outer. Associated with the inner cylinder is a pointer moving on a scale of 8, showing the length of the capillary L.

 When feeding into the chamber 4 of the test fluid, the position of the inner cylinder and the length of the slotted capillary L in the equilibrium position are established on the basis of the condition that the sum of the friction forces of the flow on the side surface of the inner cylinder, the fluid pressure on its end surface, and the gravity of the load acting on the inner cylinder are equal to zero. Due to the fact that the friction force of the flow on the side surface of the inner cylinder is proportional to the length of the capillary and the viscosity of the test fluid, the position of the inner cylinder and the length of the capillary at a constant flow rate of the test fluid are determined by its viscosity.

 The proposed design of the viscometer, as well as the design selected as a prototype, provides a measurement of the viscosity of liquids in a wide range due to automatic changes in the geometric dimensions of the capillary.

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где F вес груза;
Q расход исследуемой жидкости,
L длина капилляра,
β R_o/R_i безразмерный параметр;
R_о радиус наружного цилиндра вискозиметра;
R_i радиус внутреннего цилиндра вискозиметра.The viscosity of the test fluid is determined by the following formula:
μ

•

where F is the weight of the cargo;
Q flow rate of the test fluid,
L capillary length
β R _o / R _i dimensionless parameter;
R _{about the} radius of the outer cylinder of the viscometer;
R _{i the} radius of the inner cylinder of the viscometer.

 Formula (I) is obtained from the condition that the sum of the forces acting on the inner cylinder 2 of the viscometer in equilibrium be equal to zero. From formula (1) it follows that the viscosity of the test fluid is inversely proportional to the length of the slotted capillary L, therefore, the relative error in determining the viscosity by formula (1) is proportional to the relative error in measuring the length of the capillary.

 The proposed design of the viscometer can significantly improve the accuracy of measurements in a wide range of viscosity of liquids, which makes it suitable for use in many industries.

Claims (1)

 A viscometer comprising a fluid supply system with a flow meter and a slotted capillary formed by the lateral surfaces of two coaxial horizontal cylinders, the outer of which is rigidly fixed, and the inner has the ability to move along with the axis parallel to the outer under mechanical stress, characterized in that it is equipped with a length meter slotted capillary, and the length of the slotted capillary equal to the immersion depth of the inner cylinder into the outer.

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