The common faults and solutions of liquid-liquid extractors can be summarized into the following categories. Based on the equipment principle, operation process, and maintenance points, targeted solutions are proposed:
1、 Mechanical component failure
1. Motor or pump malfunction
-Phenomenon: Unable to start, insufficient speed, or abnormal noise.
-Reason:
-The power supply is not connected or the fuse is blown;
-Wear of motor bearings or blockage of residues inside the pump.
-Solution:
-Check the power lines, switches, and fuses to ensure normal power supply;
-Clean the inside of the pump body, lubricate the bearings, and replace the motor or repair the pump if necessary.
2. Pipeline blockage or valve malfunction
-Phenomenon: Poor solvent flow, abnormal pressure, or phase separation failure.
-Reason:
-Accumulation of solid particles or high viscosity substances in the sample;
-Valve seal aging or delayed action.
-Solution:
-Add preprocessing steps (such as filtration and centrifugation) to remove particulate matter;
-Disassemble and clean the pipeline, replace clogged filter elements or valves;
-Regularly check valve sealing, apply lubricant or replace seals.
2、 Control system and software issues
1. Program error or shutdown
-Phenomenon: The screen displays error codes, process interruptions, or automatic shutdowns.
-Reason:
-Parameter setting errors (such as time and speed exceeding the range);
-Abnormal sensor signal or communication failure.
-Solution:
-Restore factory settings or reload programs, verify parameter logic;
-Check the sensor connection wire and clean the sensing probe (such as the liquid level sensor).
2. Temperature control failure
-Phenomenon: The actual temperature deviates greatly from the set value or the heating stagnates.
-Reason:
-Heating element aging or temperature control sensor misalignment;
-The water tank is short of water or has poor heat dissipation.
-Solution:
-Calibrate the temperature sensor and replace the damaged heating wire;
-Ensure sufficient water in the water tank and clean the dust on the surface of the radiator.
3、 Airtightness issue
1. Solvent leakage
-Phenomenon: Leakage at the interface, sudden drop in pressure, or diffusion of odor.
-Reason:
-The sealing ring is aging, broken, or not installed properly;
-Loose or corroded pipeline joints with perforations.
-Solution:
-Replace the sealing ring (it is recommended to check it every 6 months);
-Use tools to tighten the joints and apply vacuum grease to enhance sealing;
-For corrosive solvents, use seals made of fluororubber or PTFE material.
2. Poor exhaust
-Phenomenon: The pressure gauge pointer fluctuates violently or has incomplete phase separation.
-Reason:
-Blockage of exhaust valve or bending of pipeline leads to obstruction of airflow.
-Solution:
-Clear the exhaust channel and adjust the pipeline layout to reduce resistance;
-Install a pressure buffering device (such as a one-way valve).
4、 Operation parameter setting issue
1. Low extraction efficiency or emulsification
-Phenomenon: The recovery rate of the target compound is low or it is difficult to separate the two phases after mixing.
-Reason:
-Mismatch of solvent polarity or improper pH value;
-Excessive stirring speed leads to emulsification.
-Solution:
-Optimize solvent ratio (such as increasing the density difference between organic and aqueous phases);
-Adjust the pH value of the sample to the stable range of the compound, and add a demulsifier (such as NaCl);
-Reduce the mixing intensity or extend the settling time.
2. Incomplete phase separation
-Phenomenon: Slow layering or blurry interface.
-Reason:
-The solvent density is close or the viscosity is too high;
-The sensor did not accurately identify the interface position.
-Solution:
-Replace solvent combinations with greater density differences (such as chloroform/water);
-Manually assist in phase separation or upgrade sensor sensitivity.
5、 Preventive maintenance and safety recommendations
1. Daily maintenance:
-Rinse the pipeline with blank solvent after each use to prevent residue crystallization and blockage;
-Regularly lubricate moving parts such as robotic arms and bearings.
2. Consumables management:
-Use high-purity solvents to avoid interference from impurities;
-Record solvent batches and equipment operating parameters for easy traceability of issues.
3. Safe operation:
-When handling volatile or toxic solvents, operate in a fume hood and wear protective equipment;
-Avoid overloading operation and strictly follow the instrument capacity limit when adding samples.