Viscometer principle, what is a viscometer

Viscometer, as the name suggests, is a physical property analysis instrument used to measure the viscosity of a fluid. Viscosity is an important physical parameter to measure the ability of liquid to resist flow, and the measurement of viscosity is very closely related to petroleum, chemical industry, electric power, metallurgy and national defense, etc., and is an important means of industrial process control, product quality improvement, energy conservation and development. in physical chemistry, fluid mechanics.

Viscosity measurement plays an important role in understanding fluid properties and studying flow states.

2.Viscometer principle - structure.

The upper part of the main body of the viscometer is cylindrical, and the lower part is a conical metal container, and the finish of the inner wall.

It is 8, the inner wall has a fixed indicator horizontal ring, the bottom end of the cone has a leak diameter of 14 mm high, and there are two holes in the lid of the container, one hole is for plugging rods, and the other hole is for inserting thermometers.

For this purpose, the container is fixed in a circular water bath and the viscometer is mounted on a shelf with two adjustable leveling screws.

3.Viscometer principle.

The viscometer uses the weight of the weight through a set of mechanical transmission system to generate torque to drive the pulp type rotor to rotate. Change the weight of the weight so that the blade rotor rotates against the resistance of the paint, and when its speed reaches 200r min, it can be used on the strobe timer.

A basically stable bar pattern is seen. In this case, the weight of the weight can be converted into the viscosity value of the measured paint, i.e. the ku value.

4.Viscometer Principles - Applications

In practical engineering and industrial production, it is often necessary to test the viscosity of the fluid to ensure the best process operating environment and product quality, so as to improve production efficiency. By measuring the viscosity of the liquid in the process, the data of the rheological behavior of the liquid can be obtained, which has important guiding value for the process control, conveyability and operability of the product during use. The properties of liquids are often related to changes in other properties of the product such as color, density, stability, solid content and molecular weight, and the most convenient and sensitive way to detect these properties is to detect the viscosity of the liquid.

Viscosimeter An instrument used to measure the viscosity of fluids (liquids and gases). Viscosity is the physical quantity that indicates the internal friction of the fluid when the fluid is flowing, and is the ability of the fluid to resist deformation, which is an important index used to identify some finished or semi-finished products. The viscosity varies with the fluid and with the temperature.

There are three main types: capillary viscometer, rotational viscometer and falling ball viscometer.

The viscometer is fully automatic, which can realize automatic sampling, automatic cleaning, automatic drying, and the whole process is fully automatic; There are also semi-automatic and portable ones.

It is divided into three types: dynamic viscosity, conditional viscosity (En's, Ray's, Sai's), and kinematic viscosity

There are three specific methods for viscosity determination.

Nowadays, there are many methods for viscosity measurement, such as rotation method, falling ball method, damping vibration method, cup viscometer method, capillary method and so on. The rotation method is divided into mechanical, early digital display, and current digital rotational viscometer, such as a series of viscometers produced by Shanghai Institute of Geological Instruments. For viscous fluids, such as castor oil, transformer oil, engine oil, glycerin and other transparent (or translucent) liquids, the falling ball method is commonly used; For fluids with low viscosity, such as water, ethanol, carbon tetrachloride, etc., capillary viscometers are commonly used to measure; For a viscosity of ?

S range of liquids can also be determined using the drum method.

For viscosity determination, we briefly introduce three methods here: conditional viscosity, dynamic viscosity and kinematic viscosity. Here's a quick rundown:

1. Conditional viscosity: refers to the viscosity expressed in conditional units measured by different specific viscometers, and there are three kinds of conditional viscosity commonly used in various countries:

Enchler viscosity is also known as Engler viscosity. is the ratio of the time it takes for a certain amount of sample to flow out of 200 ml of sample from an En's viscometer at a specified temperature (e.g., ) to the time (seconds) it takes for distilled water to flow out of the same volume at 20 m.

Temperature t?, En's viscosity is represented by the symbol et, and the unit of En's viscosity is conditional.

Redwood viscosity is Redwood viscosity. It is the number of seconds it takes for a certain amount of sample to flow 50 milliliters from a Rhinell meter at a specified temperature, measured in "seconds". There are two types of Viscosity: Reye's No. 1 (represented by RT) and Reye's No. 2 (denoted by RAT).

Sagbolt viscosity, i.e. Sagbolt viscosity. is a certain amount of specimen, at a specified temperature (e.g., 100?f、f210?

f or 122?f, etc.), the number of seconds required to flow 200 ml from a Saychs viscometer, in "seconds". There are two types of viscosity: Safe's general viscosity and Say's heavy oil viscosity (or Sar's furol viscosity).

2. Dynamic viscosity: t is the resistance generated when the two liquid layers are 1 cm apart from each other, and their areas are 1 (square centimeters) and the relative moving speed is 1 cm second, and the unit is Crimian seconds. 1 gram cm·s = 1 poise general:

In industry, the unit of dynamic viscosity is expressed in terms of poise.

3. Kinematic viscosity: at the temperature t, the kinematic viscosity is expressed by symbols, in the International System of Units, the unit of kinematic viscosity is s, that is, square meters per second (m2 s), and the actual measurement is commonly used in cents, (cst) indicates that the unit of centiscus is millimeters per second (i.e., 1cst=1mm2 s). The kinematic viscosity is widely used to determine the viscosity of liquid petroleum products such as jet fuel oil, diesel oil, lubricating oil, dark petroleum products, lubricating oil after use, etc., and the determination of kinematic viscosity adopts the countercurrent method.

A viscometer is a physical property analysis instrument that measures the viscosity of a fluid.

Brinell viscometer is a rotary viscometer, which is driven by a motor to rotate at a constant speed through variable speed. When the rotor rotates in a certain liquid, the liquid creates a viscous moment acting on the rotor. The greater the viscosity of the liquid, the greater the viscous moment; Conversely, the smaller the viscosity of the liquid, the smaller the viscous moment.

The viscous moment acting on the rotor is detected by the sensor and the viscosity of the measured liquid can be determined by computer processing.

There are three common types of viscometers.

Capillary viscometer. A capillary viscometer, usually a Sayri viscometer, is a common type of viscometer. Here's how it works:

The sample container (including the outgoing capillary) is filled with the sample to be measured in a thermostatic bath with a column height of h. Open the and the sample begins to flow towards the receiver while the time is calculated until the sample level reaches the scale mark. The more viscous the sample, the longer this period of time.

Therefore, this time is a direct reflection of the viscosity of the sample.

Rotational viscometer. A common rotary viscometer is a cone plate viscometer. It mainly consists of a flat plate and a cone plate.

The motor drives the plate to rotate at a constant speed through the variable speed gear, and relies on the capillary action to keep the measured sample between the two plates, and drives the cone plate to rotate by the friction between the sample molecules. Under the action of the torsion spring in the torque detector, the cone plate rotates at a certain angle and no longer rotates. In this case, the torque exerted by the torsion spring is related to the intramolecular friction (i.e., viscosity) of the sample being measured

The greater the viscosity of the sample, the greater the torque. The torque detector is equipped with a variable capacitor whose moving plate rotates with the cone plate to change its own capacitance value. This change in capacitance reflects the torsion spring torque, which is the viscosity of the sample being measured, which is displayed by the meter.

Vibrating viscometer. This viscometer works on the principle that when an object in a fluid vibrates, it is hindered by the fluid, and the magnitude of this action is related to the viscosity of the fluid.

Commonly used vibratory viscometers are ultrasonic viscometers with a shrapnel inside the detector. When excited by a pulsed current, the shrapnel generates mechanical vibrations in the ultrasonic range. When the shrapnel is immersed in the sample being measured, the amplitude of the shrapnel is related to the viscosity and density of the sample.

In the case of a known density, the viscosity value can be obtained from the measured amplitude data.

I haven't heard the word viscometer, as far as I know, viscosity is a physical property, a property of resistance to tensile force, it is tested through experiments, and it is not possible to measure it, just like the density of the material, it is its own property, and it cannot be measured with measuring tools. At present, it seems that only SPX in China can test the viscosity.

1. The machine must be kept horizontal.

2. When the rotor is put into the sample, it is necessary to avoid bubbles, otherwise the measured viscosity value will be lower, and the way to avoid it is to put the rotor into the sample at an angle, and then install the rotor, the rotor can not touch the cup wall and the bottom of the cup, and the measured sample must not pass the specified scale.

3. When measuring different samples, the rotor must be kept clean and dry, if the rotor has other samples or water residue after cleaning, it will affect the accuracy of measurement.

4. The maximum acidity (pH) should not exceed 2, if the acidity is too large, a special rotor should be selected, and the amount of Zheng product (only 16ml) should be determined when using ULA.

5. Select the viscosity standard according to the measured viscosity range, and verify the instrument before using the viscometer or rheometer each time, or calibrate it regularly to ensure the accuracy of the measurement. Silicone or oil-based standards are available in a wide range of viscosities that meet the properties of Newtonian fluids with an accuracy of 1%.