What Is In-Line Viscometer?
In-Line Viscometer is a measuring instrument used to determine the viscosity of a fluid in a tank containing piping or liquid material.
The viscosity of a fluid is called In-Line Viscometer because the device is installed directly on the manufacturing line, etc., where the viscosity of the fluid is measured, and many digital products are used to calculate the viscosity in real time. In-Line Viscometers are used not only to measure viscosity, but also as switches to activate other safety devices, adjust flow rates, stirring speeds, etc. based on the measured values.
In-Line Viscometer Applications
In-Line Viscometers are used in chemical, industrial, and food processing plants. When selecting an In-Line Viscometer, it is important to consider the flow rate, viscosity, measurement accuracy, ease of maintenance, and ease of monitoring output.
In addition, since viscosity changes depending on temperature, a product that can simultaneously measure the temperature of the measuring section is suitable if the temperature or other environmental factors change during the plant process.
The following are examples of In-Line Viscometer applications.
Monitoring the degree of mixing during stirring operations in a chemical plant
Control of food conditions in transport pipes in food factories
Viscosity control of paints in paint manufacturing processes
Viscosity control of coating materials in paper mills
In-Line Viscometer Principle
Most In-Line Viscometers calculate the viscosity of a fluid based on the amount of resistance to torsional rotation. This type of viscometer is sometimes described as an oscillating type because it measures viscosity by applying torsional vibration to a rod.
In-Line Viscometer of the vibrating type has two inertial masses with the same mass of inertia attached to both ends of a long, thin rod called a torsion rod, one of which is placed in the fluid as a detector. When rotational vibration is applied with the longitudinal direction of the torsion rod as the axis of rotation, the torsion rod is subjected to external torsional force because the measuring element in the viscous liquid is resisted by the inertia mass in the air.
The measuring principle of the In-Line Viscometer is to calculate the change in amplitude of vibration between the inertial mass in air and the measuring element in liquid as the change in viscosity. The vibration of the torsion rod is generated using a ceramic actuator or similar device. Ceramic actuators are also called piezoelectric (piezoelectric) actuators and have a property called the piezoelectric effect, whereby they deform and generate a voltage when an external force is applied.
In-Line Viscometer Structure
An In-Line Viscometer consists of two parts: a measuring section that is connected to the inside of a pipe or tank, and an operating and display section that calculates and outputs the viscosity.
The measuring section has a housing for connection to piping, and inertia masses of the same size are installed in the housing at the top and bottom. The upper inertia mass is immersed in air and the lower inertia mass is immersed in liquid, and each is subjected to different resistance when measuring viscosity.
The thin rod connecting the two inertia masses is a torsion rod. The torsion rod is subjected to a torsional force depending on the magnitude of the viscosity of the liquid. There is a drive unit to apply torsional vibration to the inertia mass and the torsion rod, to which a ceramic actuator is attached.
Other Information on In-Line Viscometer
Definition of Viscosity
Viscosity is described in terms of a liquid sandwiched between two plates. First, when one of the two plates is fixed and the other is shifted horizontally at a certain speed, the relative speed of the two plates divided by the distance between them is the shear rate.
The resisting force from the frictional force generated between the two plates is called the shear stress. Viscosity of a liquid is defined as the coefficient μ when shear rate V and shear stress τ are applied to the following equation (μ = τ/V).
Viscosity is not always constant regardless of shear rate. Fluids whose viscosity remains constant regardless of shear rate are called “Newtonian fluids” and those whose viscosity is not constant are called “non-Newtonian fluids. Non-Newtonian fluids are further classified into three categories based on their characteristics: plastic fluids, quasi-plastic fluids, and dilatant fluids.