There are differences between cone plate viscometers and rotary viscometers in terms of measurement principles, structures, applicability, and operational characteristics. The following is a specific analysis:

Measuring principle

　　Cone plate viscometerMeasure the viscosity of a liquid using the shear force between a conical rotor and a flat plate. The coaxial component consists of a flat plate and a circular conical plate, with the liquid sample sandwiched between them. The electric motor below drives the flat plate to rotate at a constant speed through a variable speed gear. Under the capillary action, the tested sample drives the cone plate to rotate by the frictional force between the sample molecules. Under the action of the built-in torsion spring in the torque detector, the cone plate rotates a certain angle and stops. At this time, the torque applied by the torsion spring is related to the internal friction force (i.e. viscosity) of the measured sample molecules. The higher the viscosity of the sample, the greater the torque of the torsion spring. The torque detector is equipped with a variable capacitor, whose rotor changes its capacitance value with the rotation of the cone plate. The change in capacitance value reflects the change in torsion spring torque, which is then converted into the viscosity of the measured sample.

Rotational viscometer: using different types of rotors to apply shear force in a flowing state, measuring the viscosity of liquids. After starting up, first check the zero position, and then install an inner cylinder with a radius of R2 coaxially in the outer cylinder with a radius of R1, filled with viscous fluid. The synchronous motor rotates at a stable speed, sequentially scaling the disc, and then drives the inner cylinder (i.e. rotor) to rotate through the balance spring and shaft. The inner cylinder is subjected to the viscous torque based on the fluid, and the greater the effect, the greater the torque generated by the balance spring in opposition to it. The pointer on the dial also indicates a larger scale, and the reading is multiplied by a specific coefficient to obtain the dynamic viscosity of the liquid.

structure

Cone plate viscometer: usually composed of a cone, motor, measuring equipment, etc., cone plate and flat plate are easy to install and clean.

Rotational viscometer: composed of a measurement system, liquid container, housing, etc., usually with adjustable rotor and speed, suitable rotor and speed can be selected according to the viscosity of the liquid sample.

Scope of Application

Cone plate viscometer: suitable for measuring liquid samples with medium to high viscosity, commonly used for rheological research of liquid and semi-solid substances, such as polymer materials, coatings, colloids, etc. It focuses more on measuring the accurate value of liquid viscosity, and has a small amount of sample, making it easy to fill and clean, and can measure the normal stress difference.

Rotational viscometer: suitable for measuring liquid samples with medium to high viscosity, widely used for viscosity measurement of liquid and semi-solid substances, such as oils, paints, coatings, plastics, food, drugs, adhesives and other fluids. It focuses more on measuring the sensitivity of viscosity to shear deformation.

Operation characteristics

Cone plate viscometer: The instrument has a stable and accurate rotational speed, clear button markings, easy operation, and programmed design. When the torque is below 20% (or 10%) (based on the instrument alarm limit) and above 90%, the measuring instrument will emit an alarm sound. The screen directly displays viscosity, speed, percentage scale, rotor number, and the maximum measurable viscosity value of the selected rotor at the current speed. The main control board and sub driver board all adopt surface mount technology, and the circuit design adopts advanced microcomputer processors. The structural layout is reasonable and compact. Provide RS232 interface, and the printing interval can be set by the user themselves. The instrument's full range and linearity at all levels are calibrated through a PC interface, and its performance and functionality have reached the advanced level of the same type abroad.

Rotational viscometer: It adopts advanced mechanical design technology, manufacturing process, and microcomputer control technology, with accurate data acquisition, high measurement sensitivity, reliable test results, easy operation, and beautiful appearance. The monitor adopts a white backlight and high brightness LCD display screen, which can directly display the viscosity, rotor number, speed and other information of the sample, with clear data display. Equipped with 4 types of rotors and 4 preset speeds to meet measurement requirements in different ranges. The test results can be displayed in real-time on the screen or printed out through a printer.