Which problems can be self-tested by the rotary evaporator? Yu Xiang answers for you

The rotary evaporator is mainly used for continuously distilling a large amount of volatile solvent under reduced pressure, especially for concentration of the extract and distillation of the receiving liquid during chromatographic separation, and the reaction product can be separated and purified.

Before using the rotary evaporator, we recommend that the staff first understand some basic knowledge about the product and how to deal with it, which will help the work to develop smoothly.

The basic principle of a rotary evaporator is vacuum distillation, that is, under reduced pressure, the distillation flask is continuously rotated as the solvent is distilled.

The distillation flask may be a pear or round bottom flask with a standard ground port, connected to a pressure reducing pump via a highly refluxing serpentine condenser, and the other opening of the reflux condenser is connected to a receiving flask with a grinding port for The organic solvent that is evaporated is received. There is a three-way piston between the condensing tube and the decompression pump. When the system is connected to the atmosphere, the distillation flask and the liquid-receiving flask can be removed and the solvent is transferred. When the system is connected with the decompression pump, the system should be reduced. Pressure state.

When using, depressurize first, then start the motor to rotate the distillation flask. At the end, stop the machine first, then pass the atmosphere to prevent the distillation flask from falling off during rotation. As a heat source for distillation, it is often equipped with a corresponding constant temperature water tank.

What should I do if the vacuum evaporator is not in use during the use of the rotary evaporator? We need to understand what the possible causes are:

1. The capacity of the vacuum oil pump is reduced.

2. The vacuum tube is loose, the joint is loose, and the vacuum gauge is leaking.

3. There is solvent in the container, which is limited by the pressure of the saturated injector.

4. The magnetic particle flaw detector is used for holding pressure test. In the absence of any solvent, all external butterfly valves and pipelines are shut off, and the pressure gauge is kept for one minute. The vacuum gauge pointer should not move, indicating that the airtightness is good, and vice versa.

5. There are debris in the discharge valve and pressure control valve.

6. The glass wool cotton sandwich panel is damaged.

Solution:

1. Vacuum oil pump changes oil (water), cleaning and maintenance.

2. Detect and eliminate piece by piece along the vacuum pipeline.

3. Empty the solvent and test the empty bottle.

4. Reassemble, clean the glass wool sandwich panel, apply vacuum grease, and tighten the flanges. Update the failed seal.

5. Cleaning.

6, update or repair.

The rotary evaporator performance overview has the following points:

1, long-lasting seal - from the seal design and material selection to ensure the corrosion resistance and long life of the dynamic seal system.

2, the bath pot lift - the glass is fixed, the glass is not easy to damage during operation.

3, precision intelligent temperature control, bath temperature fluctuation is one-tenth of the ordinary two-position temperature control. Can reduce the amount of material. The use of non-contact technology, no spark, safety, durability.

4, the bottle withdrawal device - can easily retract the rotating bottle to reduce glass damage.

5, low temperature cold trap - condensed with ice, dry ice, suitable for low boiling point solvent recovery.

6, F4 socket - can greatly reduce the phenomenon of "killing" of glass grinding, reduce damage and increase air tightness.

The rotary evaporator has a built-in lift motor that automatically raises the flask to a position above the heating pot when the power is off. Due to the centripetal force and friction between the liquid sample and the evaporation bottle, the liquid sample forms a liquid film on the inner surface of the evaporation bottle, and the heat receiving area is large; the force generated by the rotation of the sample effectively suppresses the boiling of the sample. The above features and its convenient features allow modern rotary evaporators to be used to quickly and gently distill most samples, even for operators with no operational experience. Deeply welcomed by users, feedback from users, below, Yuxiang instrument experts have answered some common problems of rotary evaporator.

First, why is there sometimes a water pump with two rotary evaporators, the evaporation speed of the two sets is not the same, and the vacuum of the other one is obviously not going down? Is there a poor airtightness?

Answer: Due to the limited pumping capacity of the pump, when the pump is dragged two times, the main pump power will be larger than that of the auxiliary pump, resulting in different vacuum levels of the two units, and the evaporation rate is also different.

Inspection method: The two steamed vacuum line joints are interchanged. If it becomes another vacuum, it is proved that the pump's auxiliary pump power is reduced.

Second, why does the laboratory have a large organic solvent smell when working on a large rotary evaporator?

A: Some customers will use tap water as cooling water to cool the organic steam. This can only be achieved when the winter is very cold in the north. Generally, the tap water temperature will be around 12 ° C ~ 25 ° C. In principle, the temperature of the cooling water bath and the steaming water bath The temperature of the pot should be different by more than 40 °C. Because the temperature of the tap water or the condensate bath facility is not low enough, the organic steam has not been completely condensed into a liquid and is pumped into the atmosphere by vacuum pump, which is not good for the laboratory personnel and the environment. influences.

Inspection method: The condensed droplets of steam can not appear above the upper end of the condensing tube of the rotary evaporator, so that the organic vapor can be completely condensed at the 3/4 position of the lower end of the condenser.