1Glass rotary evaporatorFault diagnosis and elimination of insufficient vacuum degree
Phenomenon: Abnormal reading on the vacuum gauge (higher than expected), reduced collection of condensate, and inability of the system to maintain a stable vacuum.
1. Sealing system failure
Aging/damage of sealing ring: Check whether the main shaft sealing ring and the discharge valve O-ring are cracked or deformed. If they are found, they need to be replaced immediately (recommended material: fluororubber).
Loose interface or foreign object blockage: Check whether the grinding joint and vacuum tube connection are loose, and spray ethanol on the suspicious area to observe whether bubbles are formed; If foreign objects are found, use an ultrasonic cleaner (40kHz) in combination with acetone to clean the internal crystals.
Improper application of vacuum grease: The contact surface between the rotary evaporator spindle and the sealing ring should be evenly coated with high vacuum silicone grease to ensure sealing.
2. Decreased performance of vacuum pump
Emulsification or viscosity reduction of pump oil: Replace the dedicated vacuum pump oil and clean the oil-gas separator.
Loose pipes or blocked check valves inside the pump head: Disassemble the pump head to check the integrity of the diaphragm and clean the check valve with ethanol.
Insufficient power of vacuum pump: If the system resistance is too high (such as pipeline bending or low condenser efficiency), it is necessary to replace the high-power vacuum pump (such as replacing the circulating water pump with a diaphragm pump).
3. Insufficient efficiency of the condensing system
Cooling water temperature too high: Adjust the water temperature to 5-10 ℃ to avoid the accumulation of gaseous solvents.
Blockage of condenser pipeline: Clean the condenser pipeline monthly to ensure sufficient condensation of gaseous solvents.
4. Limit on saturated vapor pressure of solvents
Residual high volatile solvents: Empty the rotary bottle and collection bottle, and if necessary, rinse the system with low boiling point solvents (such as dichloromethane).
5. Glass components are damaged
Crack detection: Use polarized light to detect whether there are micro cracks on the inner wall of the rotating bottle and condenser, and replace damaged parts in a timely manner.
2、 Fault diagnosis and elimination of boiling problem
Phenomenon: The solution boils violently, splashes, and even rushes out of the evaporation bottle.
1. The temperature of the water bath is too high
Improper temperature setting: Lower the temperature of the water bath to below the boiling point of the solvent (such as ethanol temperature not exceeding 35 ℃).
Large temperature fluctuations: Calibrate the temperature control system to avoid dry burning, and use explosion-proof heating tubes for greater safety.
2. Abnormal rotation speed
Excessive rotation speed: Adjust the rotation speed according to the properties of the solution (usually 50-200rpm) to avoid local overheating.
Unstable speed: Check the motor connection wires and carbon brush wear, and regularly maintain the motor.
3. Solution properties and improper handling
Solid precipitation: Reduce the intensity of negative pressure distillation or use atmospheric pressure distillation.
Insufficient recycling bottle capacity: Replace the large capacity recycling bottle to avoid excessive solvent causing a sudden increase in pressure.
Ventilation valve control: Slightly open the ventilation valve to balance the system pressure (requiring full monitoring by the operator).
4. Excessive immersion depth
Immersion of the evaporator bottle too deep: Adjust the immersion depth of the evaporator bottle in the water bath to avoid boiling caused by high temperature and fast speed.
IIIGlass rotary evaporatorSystematic maintenance suggestions
Daily inspection:
Vacuum grease coverage status, cooling water flow rate, pump oil level.
Integrity of glass components (cracks, wear).
Monthly maintenance:
Clean the condenser pipeline and test the pressure holding performance (a vacuum drop of ≤ 5% within 1 minute after closing the valve is considered qualified).
Annual maintenance:
Replace all sealing rings and calibrate the vacuum gauge and temperature control module.
Operating standards:
Avoid using beyond the range (solution volume ≤ 50% of the evaporation bottle).
Regularly clean the evaporator, condenser, and motor heat dissipation port.