Pick a rotary evaporator for solvent recovery on three specs: evaporating flask size matched to your real batch volume, manual versus electric lift matched to flask weight, and bath heating power strong enough to sustain rotary evaporation at the rate you need. We build this line from 1 L to 50 L, so here is how the models split.
What does a rotary evaporator do in a solvent recovery line?
A rotary evaporator closes a loop. The rotating flask spreads your mixture into a thin film, the heated bath supplies the energy that evaporation keeps pulling out of the liquid, vacuum holds the solvent’s boiling point down so the film evaporates fast, and the condenser turns the vapor back into liquid that drains into the collecting flask. We build our rotary evaporators around exactly that loop: evaporation, concentration and solvent recovery, always with vacuum and condenser support behind the glass.
That framing matters because it tells you what “recovery rate” actually is. It is not a number printed on the rotary evaporator itself. It is the speed of the slowest stage in the loop — the heat the bath can deliver, the vapor the condenser can re-liquefy, and the vacuum level the pump can hold while cold solvent vapor flows through it. If you want the mechanism first, our explainer on how a rotary evaporator works, from the rotating film to the receiving flask covers the principle. This article picks up where that one stops and turns the spec sheet into a buying decision.
Which flask size matches your actual batch volume?
Size on the evaporating flask, not the collecting flask. The evaporating flask is the ceiling on your batch; the collecting flask only decides how often you stop to drain recovered solvent. On our benchtop RE line the choice is simple:
| Model | RE-101 | RE-201D | RE-301 |
|---|---|---|---|
| Evaporating flask capacity | 1L | 1L | 3L |
| Collecting flask capacity | 1L | 1L | 1L |
| Glass material | GG3.3 borosilicate glass | GG3.3 borosilicate glass | GG3.3 borosilicate glass |
| Vacuum | up to -0.095MPA | up to -0.095MPA | up to -0.095MPA |
| Motor power | 40W | 40W | 40W |
| Rotation speed | 0-120 | 0-120 | 0-120 |
| Bath size (mm) | 260*150 | 260*150 | 260*150 |
| Bath lift | Manual | Manual | Manual |
| Heating power | 1000W | 1000W | 1000W |
| Temperature range | Room temp~200℃ | Room temp~200℃ | Room temp~200℃ |
| Temperature accuracy | ±1℃ | ±1℃ | ±1℃ |
| Power supply | AC220V; /50Hz | AC220V; /50Hz | AC220V; /50Hz |
The RE-101 and RE-201D carry a 1 L evaporating flask on a 24# ground joint; the RE-301 steps up to a 3 L flask on a 50# flange port. All three share the same 260×150 mm bath, 1000 W heater, 0–120 rpm range and manual lift. If your routine batch sits around 5 L, our benchtop 1 L–3 L rotary evaporator line is too small and you move to the RE-501:
| Model | RE-501 |
|---|---|
| Evaporating flask capacity | 5L |
| Glass material | GG3.3 borosilicate glass |
| Vacuum | up to -0.095MPA |
| Motor power | 40W |
| Rotation speed | 0-120 |
| Bath size (mm) | 280*160 |
| Bath lift | Manual |
| Heating power | 1500W |
| Temperature range | Room temp~200℃ |
| Temperature accuracy | ±1℃ |
| Power supply | AC220V; /50Hz |
The 5 L rotary evaporator (RE-501) keeps the same 40 W motor and 0–120 rpm rotation but pairs a larger 280×160 mm bath with 1500 W of heating power. Two judgments from our own testing. First, a flask that is nearly empty forms a poor film — an oversized unit runs slower than a right-sized one, so skip the 5 L if your batch never exceeds 3 L. Second, note the collecting flask on the benchtop line is 1 L across the board: on a recovery run where most of the batch is solvent, plan your drain intervals around that.
When does the lift type stop being a convenience?
At 1–5 L the manual lift on the benchtop line is genuinely fine — the flask is light, and you lower it into the bath once per run. The calculation changes at 10 L and above. A charged 20 L flask is heavy, the bath under it is hot, and during recovery work you raise and lower the flask repeatedly: loading, unloading, and pulling the flask out of the bath fast when foam starts climbing. That is why every model in our 10–50 L line uses an electric lift:
| Model | KRE-6010 | KRE-6020 | KRE-6030 | KRE-6050 |
|---|---|---|---|---|
| Evaporating flask capacity | 10L | 20L | 30L | 50L |
| Collecting flask capacity | 5L | 10L | 10L | 20L |
| Vacuum | -0.095Mpa | -0.095Mpa | -0.095Mpa | -0.095Mpa |
| Motor power | brushless 250W | brushless 250W | brushless 250W | brushless 250W |
| Rotation speed | 20-120 | 20-120 | 20-120 | 20-90 |
| Bath size (mm) | φ350*H220 | φ450*H250 | φ500*H270 | φ550*H320 |
| Bath lift | Electric | Electric | Electric | Electric |
| Total power | 2800W | 5300W | 5300W | 7800W |
| Power supply | 220V/50Hz | 220V/50Hz | 220V/50Hz | 380V/50Hz |
If an operator handles the flask more than a couple of times per shift, buy the electric lift and stop debating it — the automatic lift rotary evaporator line from 10 L to 50 L exists for exactly that workload. Two more things this table tells you. The KRE-6050 tops out at 20–90 rpm where smaller models run 20–120: a 50 L flask spins slower by design, that is correct engineering and not a downgrade. And the KRE-6050 is the only model in the whole range that needs a 380 V/50 Hz supply — check your site power before you order it, not after.
How do bath power and condenser capacity set your real recovery rate?
This is the rule vendors publish the specs for but never state. The bath’s job in solvent recovery is not to boil anything; it is to replace the heat of vaporization as fast as evaporation removes it. When the bath cannot keep up, the liquid in the flask cools, the boiling point stays low but the vapor flow dies, and your recovery rate collapses no matter how deep the vacuum is.
Read the power column across our line with that in mind: 1000 W on the 1–3 L benchtop baths, 1500 W on the 5 L RE-501, then 2800 W total power on the KRE-6010, 5300 W on the 20 L and 30 L models, and 7800 W on the 50 L KRE-6050. The bath grows with it — from 260×150 mm on the benchtop line to φ550×H320 on the 50 L — because a bigger flask needs a bigger heated surface, not just a hotter one.
Heat in is only half the loop. The condenser must re-liquefy vapor at least as fast as the bath generates it, or solvent passes through to your vacuum pump. An undersized cooling source does not announce itself on a datasheet; it shows up as solvent smell at the pump exhaust and a vacuum reading that will not hold. How much cooling you need depends on your solvent’s heat of vaporization and the temperature margin between your cooling medium and the solvent’s boiling point under vacuum — a volatile solvent at deep vacuum moves far more vapor per degree of bath margin than a heavy one. That is why condenser type and cooling source are items we confirm on every order, alongside flask volume, vacuum pump, bath temperature, lift mode and solvent characteristics. The practical takeaway: match the chiller to the bath power and the solvent, not to the flask size.
A five-step decision flow
Run these five questions in order and you land on a model:
| Step | Ask yourself | What the answer points to |
|---|---|---|
| 1 | Largest single batch volume? | Up to 3 L → RE-101/RE-201D/RE-301; around 5 L → RE-501; 10–50 L → KRE line |
| 2 | How often is the flask raised per shift? | Rarely → manual lift is fine; repeatedly → electric lift (KRE line) |
| 3 | What supply does your site have? | 220 V/50 Hz covers everything up to the KRE-6030; the KRE-6050 needs 380 V/50 Hz |
| 4 | How much bath temperature headroom do you need? | The benchtop line runs room temp to 200℃ with ±1℃ accuracy — check that against your solvent under vacuum |
| 5 | What cooling source can you supply? | Match chiller capacity to bath power and solvent, or the condenser becomes the bottleneck |
Most buyers stall at step 1 because they size for the batch they hope to run next year. Don’t. A rotary evaporator earns its keep at the batch size you run every week, and an oversized flask forms a worse film at partial load. Buy for today’s volume; the line is deep enough to scale later.
What vacuum pump and cooling source do you pair with it?
Every model we build is rated to -0.095 MPa at the system level, from the 1 L RE-101 to the 50 L KRE-6050, and all glassware is GG3.3 borosilicate. That vacuum rating is the ceiling the glass and seals support — what you actually hold during a run depends on the pump, the condenser temperature, and the vapor load your solvent throws at them. A pump that is generous on a 1 L flask can be marginal behind a 50 L flask evaporating a volatile solvent flat out.
Treat the rotary evaporator, pump and chiller as one purchase. We size them together because the failure modes pair up: weak pump plus strong bath floods the condenser, strong pump plus weak chiller sends solvent into the pump oil. Our guide to matching a rotary evaporator with the right vacuum pump and chiller walks through the pairing logic in detail, and it is the checklist we use ourselves before confirming a configuration.
FAQ
How full should the evaporating flask be for solvent recovery?
Partial fill only. Rotation needs free surface area to spread the liquid into a thin film, and a flask loaded toward the neck bumps raw mixture into the condenser instead of evaporating it cleanly. If you routinely have more batch than one flask load, step up a flask size rather than overfilling — that is the difference between the RE-301 and the RE-501, and between the KRE-6020 and KRE-6050.
What vacuum level do I need for solvent recovery?
Our whole line is rated to -0.095 MPa, which covers routine volatile-solvent recovery with a properly matched pump and chiller. Whether that is enough for a specific solvent depends on its boiling curve and the bath temperature you want to hold — the lower the temperature your product tolerates, the deeper the vacuum you need. Give us the solvent and your target bath temperature and we will confirm the combination rather than guess.
Do I need a special power supply for the 50 L model?
Yes. The KRE-6050 runs on 380 V/50 Hz with 7800 W total power, while every smaller model — benchtop and KRE-6010 through KRE-6030 — runs on 220 V/50 Hz. Confirm your site supply before ordering the 50 L; retrofitting power after the unit arrives is the delay we see most often on this model.
Is a rotary evaporator the right tool, or do I need molecular distillation?
For bulk recovery of a volatile solvent — where the solvent is what you want to keep and it evaporates far easier than everything else in the flask — rotary evaporation is the right tool. If instead your valuable fraction is the high-boiling, heat-sensitive residue that stays behind, that is a different separation problem; our molecular distillation equipment selection guide covers that case.
The bottom line
Batch up to 3 L: the benchtop RE line, manual lift, 1000 W bath. Around 5 L: the RE-501 with its 1500 W bath. Ten liters and up, or any workload where the flask moves more than occasionally: the electric-lift KRE line, sized by the flask, with the chiller and pump matched to the bath power and your solvent. Browse the full range in our rotary evaporator category, and if your solvent, batch size and site power do not land cleanly on one model, the answers on our FAQ page or a message with your operating conditions will get you a confirmed configuration.