The precise measurement principle of the kinematic viscosity analyzer is mainly based on capillary method or Stokes' law, combined with Newtonian fluid mechanics theory. In capillary method, the instrument measures the time required for a certain volume of liquid to flow through a calibrated capillary at a constant temperature, and calculates the kinematic viscosity by combining the product of capillary constant (C) and flow time (t) (ν=C · t). This process strictly follows the Hagen Poiseuille law, ensuring that the liquid flow time is within a reasonable range of 30-300 seconds to reduce errors. For non Newtonian or complex fluids, instruments may use rotational or shear force measurement techniques to indirectly derive viscosity values by applying shear forces and recording fluid deformation rates.
Temperature control technology is the core of ensuring measurement accuracy. The kinematic viscosity analyzer commonly uses high-precision temperature control systems, such as the German Pt100 stainless steel temperature sensor, combined with a micro rotor and U-shaped tube design, to achieve a stable environment with a temperature control range of -20 ℃ to 150 ℃ and an accuracy of ± 0.01 ℃. Thermostatic baths usually use methyl silicone oil or anhydrous ethanol as the medium, and dynamically adjust the heating power with PID algorithm to ensure temperature fluctuations of ≤± 0.01 ℃. Some models are equipped with a four channel independent temperature control system, which can simultaneously process samples with different temperature gradients, improving detection efficiency. In addition, the instrument has built-in liquid level protection and over temperature alarm functions. When the constant temperature liquid is below the safety threshold, it automatically stops heating to avoid measurement deviation caused by temperature fluctuations or medium evaporation.
By combining precise measurement principles with temperature control technology, the kinematic viscosity analyzer can achieve accurate detection over a wide range of 0.1-10000 mPa · s, meeting the stringent requirements for fluid viscosity in industries such as petroleum, chemical, and food.