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Abnormal Phenomenon and Countermeasure of Rotary Evaporator


Abnormalities and countermeasures

In case of any concerns, make an inspection according to the following table and take countermeasures. Make direct contact with local dealers or the Company if the difficulties persist. 


Inspection Items


Pumping failure of vacuum

1. The container has solvent inside, and it is contained by saturated vapor pressure.

2. The capacity of the vacuum pump is reduced.

3. The vacuum leather hose and connectors are loose, and leakage is found at the vacuum gauge.

4. During the pressure maintaining experiment of the instrument, turn off all external valves and pipelines to maintain pressure for one minute without any solvent; if the pointer of the vacuum gauge is still, this indicates that the air tightness is favorable; if not, see countermeasures to the right.

5. There is debris inside the feeding valve and the pressure control valve.

6. The glass is damaged.

1. Empty the solvent and test it with an empty bottle.

2. Replace the oil (water) of the vacuum pump, rinse and overhaul.

3. Inspect and exclude section by section along the vacuum line.

4. ① Reassemble, scrub the grinding mouth of the glass clean, coat with vacuum silicone grease, align and tighten up the flange.

② Replace the fault seal ring.

5. Clean.

6. Replace or repair.

No heating of bath boiler

1. The bath boiler has no digital display.

2. The green 'OUT' or 'ON' indicator of the temperature controller illuminates, but heating does not occur.

3. When the bath temperature is lower than the set temperature, the green 'OUT' or 'ON' indicator of the temperature controller does not illuminate.

4. The temperature controller displays 'OVER' or '000'.

1. Inspect power supply 220V.

2. Replace the heating ring.

Replace the solid-state relay or relay plate.

3. Replace the temperature controller.


4. Inspect the probe's wiring or replace the probe.

Temperature rushing of bath boiler

3. When the bath temperature is higher than the set temperature, the green 'OUT' or 'ON' indicator of the temperature controller does not distinguish it. (1-2℃ is within normal scope)

2. The green 'OUT' or 'ON' indicator of the temperature controller distinguishes, but heating continues.

3. The digital display bath temperature is far lower than the actual bath temperature.

1. Replace the temperature controller.


2. Replace the solid-state relay or relay plate.


3. Replace the probe or temperature controller.

Galloping of electric motor

(at maximum speed)

1. Inspect whether the coil of the tachogenerator is broken, and use a multimeter to measure the '1, 2' foot of the seven core plug (plug aligning to both sides of the channel); normal resistance should be about 400Ω.

2. A short circuit occurs between the coil of the electric generator and the shell.

3. The magnetic ring of the electric generator does not rotate.

4. The magnetic ring of the electric generator is broken.

1. If the electric generator is broken, replace the coil or put the open-circuit contact through.


2. Loosen the electric generator cap behind the motor to exclude the circuit.

3. Tighten the M5 nut.

4. Replace the magnetic ring of the electric generator.

Motor heating

1. Temperature rising of the motor (shell temperature-room temperature)

△T≤40℃ is within normal scope.

2. In case △T>40℃, take countermeasures to the right.

3. If the flat display part illuminates indicating the electric overload of the motor, take countermeasures to the right.

1. It is allowable to continue utilization without any handling measures.


2. ① Downsize the wing of the agitating valve to reduce the load.


② Increase the rotation speed as appropriate and use mediate speed.


③ Avoid the point of resonance during rotation.


④ Eliminate the abnormal resistance of the mechanical part.


⑤ Maintain the sealing and lubricating parts.


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