The sensor probe of the online viscometer in the reaction kettle directly contacts the material, and its cleanliness and integrity directly affect the measurement accuracy and equipment life. Cleaning and maintenance should be combined with material characteristics (such as viscosity, corrosiveness, solidity), probe types (such as rotary, vibration, capillary), and equipment operating conditions, following the principles of "regular cleaning, scientific maintenance, and precise calibration". Here are the specific operation guidelines:
1、 Core premise: Safety preparation before cleaning
Shutdown and isolation
First, shut down the stirring device of the reaction vessel, cut off the power supply of the viscometer, and ensure that the probe is in a non working state.
If there is pressure/high temperature material in the reaction vessel, it is necessary to first release the pressure to atmospheric pressure through a pressure relief valve, wait for the material to cool to below 50 ℃ (to avoid high-temperature burns or solvent vaporization), and then empty the residual material in the vessel through a discharge valve (toxic/flammable and explosive materials need to be treated according to the hazardous waste process).
protective measures
Wear acid and alkali resistant gloves, goggles, and protective clothing (for corrosive materials). If using organic solvents for cleaning, it is necessary to operate in a fume hood or explosion-proof area, and open flames are prohibited.
Tool Preparation
Basic tools: Soft bristle brush (made of nylon material to prevent metal scratches on the probe), specialized wiping cloth (lint free cotton cloth, PTFE cloth), needle tube/rinsing pot (used for narrow gaps).
Cleaning reagents: Select according to the characteristics of the material (such as deionized water for water-soluble materials; ethanol, acetone, xylene for oily/viscous materials; soak solidified materials in corresponding solvents, and prohibit direct flushing of sensitive parts of the probe with strong acids and bases).
2、 Cleaning methods for different types of probes
There is a significant difference in the structure of the online viscometer probe, which requires targeted treatment (taking the commonly used rotary and vibration types in industry as an example, with the two accounting for over 80%):
（1） Rotating probes (such as Brookfield, AntonPaar rotational viscometer probes)
Core components: rotor (measuring element), shaft sleeve, seal, prone to entanglement with viscous materials or accumulation of residue.
Conventional cleaning (when the material is not yet solidified)
Step 1: Disassemble the rotor (some probes can be cleaned online and do not need to be disassembled, please confirm the equipment manual). If disassembly is required, use a special wrench to unscrew the rotor fixing nut and gently remove the rotor (to avoid hitting the precise patterns on the rotor surface).
Step 2: Pre rinse. Rinse the rotor, shaft sleeve, and probe base with a low-pressure flushing kettle (water pressure ≤ 0.2MPa) to remove surface floating materials (high-pressure seals are prone to damage).
Step 3: Soak and wipe. Soak the rotor in a container containing cleaning reagents for 5-15 minutes (sticky materials can be extended to 30 minutes, do not soak the motor interface), gently brush the rotor gaps and shaft sleeve threads with a soft bristled brush, and then wipe with a lint free cloth dipped in the reagent until there is no residue.
Step 4: Secondary rinsing+drying. Rinse residual reagents with deionized water (or anhydrous ethanol), and finally blow dry with compressed air (to remove oil and water), or air dry naturally (avoid direct sunlight).
Stubborn stain cleaning (during material solidification/carbonization)
Do not use hard objects such as steel wire balls or sandpaper to scrape! The following methods can be used:
Solvent soaking method: Soak in a warm specialized solvent (such as ethyl acetate for curing resin, 5% dilute nitric acid for carbonized materials, and confirm the corrosion resistance of the probe material) for 30 minutes. After the stain softens, clean it with a soft bristled brush.
Ultrasonic cleaning method: Place the detachable rotor into an ultrasonic cleaning machine (with corresponding solvent added) and clean it at a frequency of 40kHz for 10-20 minutes (only applicable to pure metal rotors without electronic components).
Online in-situ cleaning (CIP, when no disassembly is required)
If the reactor is equipped with a CIP system, the cleaning nozzle can be aligned with the probe and cleaned in a cycle of "pre rinse water → alkaline solution (such as 0.5% NaOH, for oil stains) → rinse water → acid solution (such as 0.3% HNO ∝, for inorganic salts) → final rinse water". Each stage lasts for 5-10 minutes, and finally dried with compressed air.
（2） Vibration probe (such as Vibro viscometer probe, commonly used for high viscosity/granular materials)
Core components: vibrating fork/vibrating rod (sensitive element, surface with piezoelectric ceramic), protective cover, easy to attach sticky materials or get stuck particles.
Basic cleaning
Step 1: If the material has not solidified, directly use a low-pressure flushing kettle (or CIP nozzle) to flush the vibration fork gap and protective cover filter screen, and remove surface adhesion materials.
Step 2: Gently wipe the surface of the vibrating fork with a lint free cloth dipped in cleaning reagent (with light force to avoid damaging the piezoelectric element), inject a small amount of reagent into the gap with a needle tube to rinse, and then rinse with deionized water.
Particle/solidified material cleaning
If the protective cover filter is clogged, use a soft bristled brush to lightly brush the filter mesh, or use a needle to aim at the hole and blow it through (do not stab with sharp objects).
If the vibrating fork is attached to the solidified material, wrap it in a cotton cloth dipped in warm solvent and soak it for 10 minutes. After softening, gently brush it with a soft bristled brush. Do not directly break or tug on the material.
taboo
It is absolutely forbidden to immerse the vibrating probe as a whole (to avoid water ingress into the electronic interface). When cleaning, wrap the junction box/connector at the end of the probe in a plastic bag.
（3） Capillary probe (rare, used for low viscosity fluids)
Core components: capillary tubing, inlet and outlet interfaces, prone to material crystallization or particle blockage.
Cleaning method: Use a needle or micro pump to inject cleaning reagents (such as ethanol, deionized water) from the inlet end, reverse flush the capillary tube (use pressure difference to remove blockages), repeat 3-5 times until the reagent flowing out of the outlet is free of residue, and finally dry the pipeline with compressed air.