A rotary evaporator is a lab instrument that removes solvent from a sample by spinning a heated flask under vacuum. We build ours so the bath warms the mixture, the vacuum drops the solvent’s boiling point, and a condenser recovers the vapor as liquid. The result: gentle concentration and clean solvent recovery without scorching the product.
What a rotary evaporator actually is
Strip away the jargon and a rotary evaporator, or rotovap, is four parts working together: a driven flask that rotates, a heated bath under it, a condenser above it, and a vacuum line pulling on the whole assembly. Chemists also call it a rotavapor. The point of all four parts is one thing, to boil off solvent at a temperature low enough that whatever you care about, the extract, the reaction product, the concentrate, survives intact.
The rotating flask is what separates this tool from a plain distillation setup. As the flask turns, it spreads the liquid into a thin film across the glass wall. Thin film means more surface area, and more surface area means faster, more even evaporation. That is why a rotovap concentrates a sample in minutes where a static flask would take far longer and risk local overheating.
Our range covers the full span of that idea. A bench 1L automatic-lift rotary evaporator handles routine sample prep on a single-liter flask, while the 10L-50L automatic-lift models take the same physics up to pilot batches. Same working principle, different flask volume and heating budget.
How does the working principle work?
The working principle is a sequence, not a single event. Heat goes in at the bottom, vacuum pulls at the top, and the condenser catches what comes off in between. Here is the chain, start to finish.
Step one, the bath heats the flask. On our bench RE-2000 unit the heating power is 1200W and the bath runs from room temperature up to 99C, held to plus or minus 1C. That accuracy matters, because a swing of a few degrees can push a delicate compound past the point where it degrades.
Step two, the flask rotates while the vacuum holds. Rotation speed on our units runs 0 to 120 rpm, and the vacuum reaches -0.095MPa. At that reduced pressure the solvent boils well below its atmospheric boiling point, so you never have to crank the bath hot enough to cook the sample.
Step three, the vapor rises into the condenser and a cold source turns it straight back to liquid. Step four, that liquid drains into the collecting flask, five liters on the smaller scale-up models and up to twenty liters on the largest, while your concentrated product stays behind in the evaporating flask. Solvent recovered, sample concentrated, nothing wasted.
Why does a rotary evaporator need a vacuum?
Because the vacuum is what lets you evaporate gently. Every solvent has a boiling point that drops as pressure drops. Pull the pressure down to -0.095MPa and even a stubborn solvent comes off at a bath temperature that would never boil it at atmospheric pressure. That is the whole trick, and it is why a rotovap is standard kit anywhere heat-sensitive material is involved.
The alternative, boiling at full atmospheric pressure, forces you to run the bath hotter. Hotter bath, more risk of thermal degradation, oxidation, or bumping. The vacuum sidesteps all of it. It is also why matching the vacuum source and condenser to your solvent matters more than raw heating power, a point our team walks through in the rotary evaporator selection guide.
What is a rotary evaporator used for in the lab?
Three jobs come up again and again: evaporation, concentration, and solvent recovery. In our source material we position rotary evaporators for exactly these, with vacuum and condenser support doing the work. Concretely, that looks like:
- Concentrating extracts. Botanical, food, or reaction extracts get reduced from a dilute solution down to a workable concentrate without cooking off the target compound.
- Recovering solvent for reuse. The condenser sends clean solvent to the collecting flask instead of the fume hood. On the larger units that collecting flask is 10L to 20L, which adds up fast on repeat runs.
- Removing solvent after a reaction. Once a synthesis is done, the rotovap pulls the reaction solvent off so you are left with product, not a beaker of dilute liquid.
The higher-temperature manual-lift line stretches the use cases further. Our 10L-50L manual-lift rotary evaporator runs its bath up to 200C, so higher-boiling solvents that a 99C bench bath cannot touch become workable. Different bath ceiling, different chemistry on the menu.
Bench unit or scale-up unit?
This is the first fork most buyers hit, and it comes down to flask volume and power. A bench unit is built around a single small flask and modest heating. A scale-up unit carries a much larger flask, a bigger bath, and the electrical supply to match. The numbers make the gap obvious.
| Spec | Bench (RE-2000) | Auto-lift 10L (KRE-6010) | Auto-lift 50L (KRE-6050) |
|---|---|---|---|
| Evaporating flask | 1L | 10L | 50L |
| Collecting flask | 1L | 5L | 20L |
| Motor power | 40W | brushless 250W | brushless 250W |
| Total power | 1000W | 2800W | 7800W |
| Power supply | AC220V/50Hz | 220V/50Hz | 380V/50Hz |
| Rotation speed | 0~120rpm | 20-120rpm | 20-90rpm |
Read that 50L column carefully. The jump from 2800W to 7800W total power, and from a 220V single-phase supply to a 380V supply, is not a detail you retrofit later. If your batches are heading past 30L you plan the electrical service around it from the start. Skip the 50L if your batch never exceeds a couple of liters, a 1L bench unit on a standard 220V outlet does that job with far less installed load.
Manual lift or automatic lift?
The lift is what raises the flask out of the bath at the end of a run, and it splits our large-format line in two. Automatic lift is electric, driven from the control panel. Manual lift you raise by hand. Both reach the same 10L-50L flask sizes, so the choice is about workflow, not capacity.
There is a second difference buried in the specs worth knowing before you decide. Our automatic-lift KRE-6010 series pairs its electric lift with a brushless 250W motor across every flask size. The manual-lift RE-1002 series steps the motor with the flask instead, 120W on the 10L and 20L, 180W on the 30L and 50L, and pushes the bath ceiling to 200C against the bench unit’s 99C. So the manual line trades hands-on lifting for a higher-temperature bath, which is the deciding factor if your solvents are on the high-boiling end.
How do you pick the right one?
Do not start with the model number. Start with the run. Six things decide which rotary evaporator fits, and our team confirms each one before quoting: flask volume, condenser type, vacuum pump, cooling source, bath temperature, and lift mode, all read against the characteristics of the solvent you actually use.
Flask volume sets the scale, one liter for sample prep, ten to fifty for pilot batches. Bath temperature is set by your solvent’s boiling point, which is where the 99C bench ceiling versus the 200C manual-lift ceiling becomes a hard filter. The condenser and cooling source have to keep up with how fast you are boiling solvent off, and the vacuum pump has to hold -0.095MPa against your system. Get those matched and the unit runs clean. Guess at them and you either bottleneck the throughput or never hit the vacuum you need.
If solvent recovery is the main goal rather than just concentrating, the trade-offs shift again, which is the focus of our companion piece on choosing a rotary evaporator for solvent recovery. For the full parts-and-options breakdown, the rotary evaporator category page lists every configuration we build, and general purchasing questions are answered on our FAQ-Seite.
Frequently asked questions
What is the difference between a rotary evaporator and a rotovap?
None, they are the same instrument. Rotovap and rotavapor are informal names for a rotary evaporator. All three refer to the flask-bath-condenser-vacuum setup described above.
What vacuum level does a rotary evaporator reach?
Our units reach -0.095MPa. That reduced pressure lowers the solvent’s boiling point so it evaporates at a bath temperature gentle enough to protect heat-sensitive samples, rather than boiling at its normal atmospheric point.
How hot does the bath get?
It depends on the model. Our bench RE-2000 unit runs from room temperature to 99C at plus or minus 1C, which suits most common solvents. The manual-lift 10L-50L line runs up to 200C for higher-boiling solvents.
What is the largest flask you offer?
Our automatic-lift and manual-lift 10L-50L lines top out at a 50L evaporating flask, paired with a 20L collecting flask. For bench-scale work the RE-2000 line uses a 1L flask.
Do I need automatic lift or is manual lift enough?
Manual lift is enough for lower-volume or occasional use and keeps the setup simpler. Automatic electric lift helps when you run the unit often or at larger flask sizes and want the bath raised and lowered from the control panel. Both cover the same 10L-50L flask range.
Where to go from here
Match the flask volume to your batch, match the bath ceiling to your solvent’s boiling point, and confirm the vacuum, condenser, and cooling source can keep pace, in that order. A 1L bench unit and a 50L 380V pilot unit run on the same working principle but ask for very different installs, so pin the run down first. Tell us your solvent, batch size, and whether solvent recovery or concentration is the goal, and we will confirm the configuration against the parameter sheet before anything is quoted.