What is a Rotational Viscometer? A Key Device for Measuring Fluid Viscosity in the Chemical, Food, and Pharmaceutical Industries

　　In the "pulse" of process industries such as chemical, food, and pharmaceuticals, the behavior of fluids directly determines product quality, production efficiency, and process stability. From a pot of yogurt with a rich and smooth texture, a uniform and stable medicinal solution, to a bucket of paint with excellent leveling properties—behind each lies a common key control parameter: viscosity. It is not only a measure of a fluid's thickness but also a core window into understanding product stability, processability, and end-use performance.

　　So, how can we accurately quantify a fluid's resistance to flow under external forces, providing reliable data support for formula optimization, process parameter determination, and quality standard establishment? We need professional equipment—the viscometer.

　　What is a Rotational Viscometer?

　　A rotational viscometer is a precision instrument that measures the viscosity (internal friction) of a substance by simulating the fluid shear flow process. Its core principle is based on Newton's law of viscosity: when adjacent layers of fluid slide relative to each other, the internal friction (viscous resistance) is proportional to the velocity difference and the contact area, related to the fluid's properties, and independent of the contact surface pressure.

　　Among numerous instrument brands, LND has launched a series of cost-effective, robust, and durable rotational viscometers, thanks to its deep understanding of industrial application scenarios:

　　Working Principle:

　　Shear Field Construction: The instrument consists of a fixed component (outer cylinder/cone plate/parallel plate) and a rotating component (inner cylinder/rotor). The fluid is held between these two components.

　　Shear Action Generation: A motor drives the rotating component at a constant speed (ω). The fluid, due to its viscosity, resists this motion, generating a shear force (F).

　　Signal Conversion and Calculation: A sensor detects the torque (M) corresponding to the shear force. Using parameters such as rotor radius (R), height (H), and gap (δ), the viscosity is calculated via the formula η = K × S (where η is viscosity, K is the instrument constant, and S is the torque percentage).

　　Non-Newtonian Fluid Adaptation: By adjusting the rotational speed to change the shear rate (γ̇∝ω), a "viscosity vs. shear rate" curve can be plotted, revealing the fluid's shear-thinning (viscosity decreases with increasing shear rate) or shear-thickening characteristics.

　　As a well-known domestic instrument brand, LND's rotational viscometers are known for their high precision, wide measurement range, and intelligent features, catering to the needs of various industries including chemical, food, and pharmaceuticals:

　　Chemical Industry:

　　Coatings/Inks: Measure application viscosity (ensuring even coating), monitor storage stability (preventing sedimentation).

　　Polymers: Characterize plastic melt viscosity (guiding injection molding processes), evaluate the bonding performance of adhesives.

　　Food Industry:

　　Dairy Products: Control the viscosity of yogurt and cream (ensuring smooth texture).

　　Baking: Monitor the relationship between dough viscosity and gluten strength (optimizing fermentation processes).

　　Pharmaceutical Industry:

　　Injections/Oral Liquids: Control viscosity (ensuring accurate dosing).

　　Ointments/Gels: Viscosity affects skin adhesion and absorption efficiency.

　　Petroleum Industry:

　　Lubricating Oils: Classify viscosity grades (e.g., 5W-30 engine oil).

　　Drilling Fluids: Adjust viscosity to carry rock cuttings and stabilize wellbores.