RU2295718C2 - Method of determining viscosity - Google Patents

Abstract

FIELD: measuring technique.

SUBSTANCE: method comprises setting a ball in the fluid and recording the displacement of the ball. The ball is connected with the counterweight through the thread turned over the block. The masses of the ball and the counterweight are the same. The ball is submerged into the fluid down to a given lever and is accelerated under the action of buoyancy force. The value of viscosity is judged by the height to which the ball jumps over the surface of the liquid.

EFFECT: enhanced accuracy.

1 dwg

Description

The invention relates to the field of studies of the rheological properties of liquids and may find application in the industry of building materials, chemical, petroleum and other industries for determining the viscosity of opaque and transparent liquids.

A known method for determining viscosity is that a sensitive element in the form of a heavy ball connected by a flexible thread thrown through the block with a light counterweight is placed in a measured viscous medium, the counterweight is identical in shape and size to the ball with a strictly defined ratio of the density of the ball, counterweight and measured liquid, after which both bodies - the counterweight and the ball - are simultaneously immersed in the studied viscous medium. The ball is immersed by gravity and braked in a viscous medium until it stops completely; as a result, the ball is immersed in the liquid to a certain depth, the value of which is used to judge viscosity [1]. At the end of the experiment, the ball oscillates in the liquid.

The disadvantages of this method are:

1) The low accuracy of the experiment due to the fact that the frictional force in the block is not taken into account and oscillations of the ball occur after the counterweight leaves the liquid.

2) A high error in determining the viscosity due to the fact that the average value of the resistance force is substituted in the formula for calculating the viscosity instead of its actual current value.

3) The great complexity of the experiment due to the need to select a certain ratio of the densities of the ball, counterweight and the measured fluid, therefore, this method is not universal, because requires the use of balls and balances of different densities to measure the viscosity of liquids of various densities.

The closest in technical essence and the achieved effect to the proposed invention is a method for determining viscosity, which consists in the fact that the sensitive element in the form of a heavy ball connected by a flexible thread thrown through the block with a light counterweight in the air is placed in a measured viscous medium; in contrast, in the form of a transparent graduated cylinder, the test fluid is poured to balance the ball in this fluid, the ball is raised to a height h above the level of the test fluid and then immersed in the fluid to a depth l until it stops, the viscosity is calculated from l [2]. At the end of the experiment, the ball is in the liquid.

The disadvantages of this method are:

1) Low accuracy of the experiment due to the fact that the friction force in the block is not taken into account.

2) A high error in determining the viscosity due to the fact that in the formula for calculating the viscosity substitute the average speed instead of the actual current value.

3) The great complexity of the experiment due to the need to use a reference fluid and determine its mass in a graduated cylinder.

The objectives of the invention are:

1. Improving the accuracy of determining viscosity.

2. Reducing the complexity of the experiment.

The tasks are achieved due to the fact that the sensitive element in the form of a ball connected by a flexible thread thrown through the block with a counterweight in the air is placed in a measured viscous medium and the movement of the ball is recorded, the ball and the counterweight are made of the same mass, which ensures their balancing in air; the ball is immersed in a liquid to a certain depth and accelerated upwards in a measured viscous medium, after which the ball is braked in air and the height of the ball bouncing above the surface of the liquid is measured, the value of which is used to judge viscosity.

The drawing shows a General view of the experimental setup according to the proposed method, where 1 is a ball, 2 is a block, 3 is a thread, 4 is a counterbalance, 5 is a measured viscous medium. The dotted line shows the position of the ball and counterweight at the end of the experiment.

The proposed method is as follows. A sensing element in the form of a ball 1 connected by a flexible thread 3 thrown through a block 2 with a counterweight 4 in the air is placed in a measured viscous medium 5 and the movement of the ball is recorded, the ball and the counterweight are made of the same mass, which ensures their balancing in air; the ball is immersed in a liquid to a certain depth l and accelerated upward under the action of the force of Archimedes. Thus, at the surface of the liquid, the ball will have kinetic energy, which, with the further movement of the ball in air, is spent on working to overcome the frictional force in the block until it stops completely, as a result of which the ball bounces in air to a height Δh above the surface of the liquid. After that, Δh is measured, the value of which is used to determine the viscosity as follows: the lower the viscosity of the liquid, the faster the ball will accelerate and the higher it will stop in the air without any fluctuations.

An arrow is mounted on the counterweight to measure the viscosity of the measured fluid on a scale. This scale is calibrated for this installation by using various reference liquids with known different viscosities.

The amount of movement of the arrow on the scale is equal to the value of bouncing Δh, which will be different depending on the viscosity of the measured fluid.

The positive effect achieved as a result of applying this method is as follows:

1) Provides high accuracy in determining viscosity due to the fact that the current (and not average) speed is taken into account.

2) The complexity of the experiment is reduced, because there is no need to fill the counterweight with a reference fluid.

3) Low viscosity and opaque liquids can be measured with the same ball in a wide range of their densities and viscosities.

Information sources

1. USSR Copyright Certificate No. 661296, Cl. G 01 N 11/10, 1979

2. Copyright certificate of the USSR No. 616560, Cl. G 01 N 11/10, 1978

Claims (1)

The method for determining the viscosity, namely, that the sensing element in the form of a ball connected by a flexible thread thrown through the block with a counterweight is placed in a measured viscous medium and the movement of the ball is recorded, characterized in that the ball and the counterbalance are balanced between themselves in air by making them the same mass, the ball is immersed in a liquid to a certain depth and accelerated upwards in a measured viscous medium, after which the ball is braked in air and the height of the ball bouncing above the surface of the liquid is measured, the value of which is judged by viscosity using a scale of displacement of the counterweight graduated in units of viscosity when lifting the ball above the surface of the liquid.