The online viscosity meter for flasks is a device based on the principles of rotational shear or vibration shear, which monitors the viscosity of liquids in real-time inside the flask. The core is to directly contact the material through sensors and provide feedback on viscosity data, achieving continuous measurement without the need for sampling.
1、 Core working principle: two mainstream technological routes
1. Rotary flask online viscometer (commonly used)
The core of this type of equipment is to install a rotatable "rotor" inside the flask, and calculate the viscosity through the interaction between the rotor and the liquid. The specific process is as follows:
Immerse the rotor into the material: Fix the cylindrical or paddle shaped rotor onto the sensor shaft and immerse it directly in the liquid inside the flask.
Constant speed drive: The motor drives the rotor to rotate at a fixed speed (such as 10rpm, 50rpm).
Shear force feedback: The higher the viscosity of the liquid, the greater the resistance (shear force) to the rotor, which will react on the sensor shaft.
Torque signal conversion: The sensor detects the torque (torque corresponding to resistance) received by the rotor in real time and converts the mechanical signal into an electrical signal.
Viscosity calculation output: The system automatically calculates the viscosity value of the current liquid based on the core formula of "viscosity=torque/speed" (combined with compensation parameters such as rotor coefficient and material temperature), and displays or transmits it in real time to the control system.
2. Vibration type flask online viscometer (high-precision scenario)
This type measures viscosity through the high-frequency vibration of sensors and the damping effect of liquids, and is suitable for materials in low viscosity or volatile flasks:
Vibration probe implantation: Fix a quartz crystal or metal probe (such as a tuning fork) inside the flask, and the probe can generate high-frequency small vibrations (such as 32kHz).
Damping force detection: The higher the viscosity of the liquid, the stronger the damping force (hindering force) on the probe vibration, which can cause changes in the frequency or amplitude of the probe vibration.
Frequency/amplitude analysis: Sensors detect changes in vibration parameters and convert them into electrical signals related to viscosity.
Data calibration output: By pre calibrating the correspondence between viscosity and vibration parameters, real-time viscosity is calculated with higher accuracy than rotary methods and less disturbance to materials.
2、 Key structures and advantages
1. Core components
Detection unit: including a rotor (rotating type) or a vibration probe (vibrating type), which directly contacts the material inside the flask and is the core for obtaining viscosity signals.
Drive and Sensing Unit: Provides rotational power (motor) or vibration excitation (oscillator), while also having built-in torque sensors (rotary) or frequency sensors (vibration).
Temperature control and compensation unit: Some devices integrate temperature sensors, as liquid viscosity is greatly affected by temperature (such as viscosity may change by 5% -10% for every 1 ℃ temperature change). The system will automatically calibrate the viscosity value based on temperature data to ensure accuracy.
Data output unit: Display real-time viscosity data in digital form or transmit it to PLC, DCS systems through interfaces such as RS485 and 4-20mA for production monitoring or automatic control.
2. Applicable scenarios and advantages
Applicable scenarios: Mainly used for flask reaction processes in industries such as chemical, pharmaceutical, and food, such as polymer synthesis, drug dissolution, coating preparation, etc. Real time monitoring of material viscosity changes is required to control reaction progress or product quality.
Core advantage: No need for manual sampling, avoiding measurement errors caused by changes in material state (such as temperature and volatilization) during the sampling process; It can be monitored continuously for 24 hours, providing timely feedback on viscosity abnormalities and reducing the risk of product scrap.