Tired of breaking your balls?
For years, rotary evaporators have been the standard for laboratory solvent recovery, almost every research lab has one in their arsenal. Rotary evaporators are great for benchtop trials, with it’s all glass construction giving a great visual of what is happening in the process. So when it’s time to scale up production, the easy choice is to scale with bigger or more rotary evaporators, right?
No way!
Why, you ask? Rotary evaporators are great for benchtop projects but do not scale well linearly. Let’s look at why.
Fragility:
What does running a rotovap look like? You pull a vacuum on it, load your sample, start your distillation, and wait. Then comes time to remove your extract. You lower your bath, sometimes with a manual crank lift, break vacuum, wipe down the glass flask, carefully remove it, empty it out, clean it, then reassemble and start the whole process again. Unfortunately, you just lost 30 minutes of production time! Sometimes the glass is slippery from water, it can still be hot from the evaporation step, and accidents happen. One slip, now you’ve got a sticky mess on your floor with shards of broken glass, a costly replacement, and you’ve lost all your product and hard work for the day! Now let’s look at an AutoVap, it’s construction is made of all stainless steel, with a few visual indicators made of glass. It has pumps to move product in and out of the system, and can be cleaned in place, requiring almost no disassembly to clean. It is a continuously fed unit as well, so no downtime in between batches, saving you labor, and costly repairs from constant maintenance.
Heating Capacity:
Using that same 50L rotovap, let’s look at the heater element. The wattage of your heater ultimately dictates how much solvent you can recover. Ethanol, for example, requires about 700 watts per gallon to evaporate. So a 50L rotovap with 6400 watts has an absolute maximum throughput of 9.14 gallons per hour (6400 / 700 = 9.14) However, there is another factor at play, surface area, and conductivity. The rotovap sits in a water bath, usually only 1/3rd of it is immersed, limiting the amount of heat transferred from the water bath. To further reduce efficiency, the rotovap’s evaporating flask is made of glass. Let’s talk thermal conductivity. It’s commonly known that there are conductors, and insulators. A material’s thermal conductivity is rated in W/MK, that’s watts per meter Kelvin. Bear with me here. Copper is widely regarded as one of the thermal conductors, with 398 W/MK, which is why you see it used so much in heat exchangers, however, it doesn’t have the greatest range of chemical compatibility, which leads us to 304 stainless steel. 304SS has a modest 14.4 W/MK, not stellar, but it’s other properties make up for it. When you look at glass, it only has 1 W/MK. What does all this jargon mean? Simply put, stainless steel is 14 times as efficient as a conductor of heat! Meaning glass is a terrible conductor, and with it’s limited contact in a rotary evaporator, diminishes its performance even further. Coupled with the fact that a rotovap’s heating bath is open to the element, allowing heat to escape in the form of steam, most 50L rotary evaporators are only rated for 4 gallons per hour of ethanol evaporation!
Residence Time
One often-overlooked limitation of rotary evaporators—especially when scaling up—is residence time. In a rotovap, residence time refers to the amount of time the liquid extract remains exposed to heat during the evaporation process. Because the system relies on slowly rotating a round-bottom flask in a heated bath under vacuum, the sample is subjected to prolonged, low-efficiency heat transfer. With glass being a poor conductor of heat (1 W/mK), and only a portion of the flask submerged in the bath, the thermal energy takes longer to reach and evaporate the solvent. As a result, larger volumes require extended heating to achieve meaningful evaporation, drastically increasing residence time. This prolonged exposure to heat can lead to thermal degradation of sensitive compounds, reduced product quality, and inefficiencies in production workflows. Unlike continuous flow systems, which minimize residence time with faster heat exchange and fluid movement, a rotovap’s batch process inherently slows things down—making it far from ideal when consistency, throughput, and product integrity matter at scale.
Floor Space & Installation
Production floorspace can be some of the most costly space in your operation. Usually with special requirements for floor surfaces, secondary containment, C1D2 or D1 air handlers, gas detection systems, and such. Therefore it’s crucial to maximize your production space to be as efficient as possible. Let’s compare a 50L rotovap to an AV15. The rotovap takes up about 52 x 30 inches of floor space, the AutoVap 15 takes 48 x 20. However, there is a hidden factor, the chiller! While a rotovap’s chiller is usually smaller, due it’s significantly lower capacity (we’re talking 17,000 BTU versus 144,000!) The issue becomes apparent when multiple units are required. Chillers require space around them for airflow, and multiple units can quickly take up much needed utility space, although lower than production space, still extremely valuable. And there is more, most chillers spec’d for a rotovap are destined to live inside. What does that mean? Well, the heat the chiller is removing from your process is then injected into your utility space, which then needs to be cooled down again from your air conditioning unit, DOUBLING the energy cost! Our AutoVap chiller units are designed to go outside, which is the least costly space to install, keeping it out of the way of your production floor, and the heat is removed to the outside, reducing the heat load on your building. To match a AutoVap’s throughput, you would need SIX rotovaps, that take up nine times the space of an AutoVap, and require a significant amount of manual labor to operate. It’s a no brainer why the the AutoVap is more efficient spatially.
Cost per Gallon per Hour (GPH): A Clear Winner
When comparing systems for solvent recovery, cost per gallon per hour is one of the most critical performance metrics — and the difference between traditional rotary evaporators and the AV15 is staggering.
Take a standard 50L rotary evaporator setup from a well-known brand (hint: their initials match Artificial Intelligence):
- Rotovap: $13,990
- Chiller: $12,990
- Vacuum Pump: $4,125
- Total: $31,105
- Throughput: 4 gal/hr
- Cost per GPH: $7,776.25
Now compare that to the AV15, a complete turnkey system including heater, chiller, vacuum pump, and everything you need:
- Complete AV15 Package: $97,680
- Throughput: Up to 25 gal/hr
- Cost per GPH (based on 20 gal/hr conservative rate): $3,907.20
That’s nearly half the cost per gallon per hour — and that’s just the initial capital investment.
When you factor in operational costs, the difference becomes even more dramatic. The AV15 uses a closed-loop system with no atmospheric losses, making it up to 70% more efficient than electric rotary evaporators. Even better, we offer gas heater options, which not only reduce your electric load but cost about one-third as much to operate as electric heat.
Let’s break it down further:
- Energy Use: AV15 consumes just 17.5 kW compared to 38.4 kW for six rotovaps.
- Annual Energy Cost: $4,200 vs. $9,216 — saving over $5,000 a year.
- Labor: AV15 requires only 0.5 operators vs. 2.5 for rotovaps — saving $100,000/year.
- Maintenance: ~$1,000 for AV15 vs. $3,000 for rotovaps.
- Facility Space: AV15 needs just 6.7 sq. ft. vs. 90 sq. ft. for six rotovaps — saving over $8,000/year.
Put it all together, and here’s the bottom line:
- Total Annual Operating Cost: $30,870 for AV15 vs. $146,216 for rotovaps.
- Total Year 1 Cost (CapEx + OpEx): $128,550 for AV15 vs. $332,846 for rotovaps.
- Year 1 Cost per Gallon: $2.57/gal for AV15 vs. $6.93/gal for rotovaps.
That’s over 60% savings in the first year alone — and with less labor, less energy, less downtime, and less space required, the AV15 doesn’t just outperform—it pays for itself in under 1.5 years!
AV15 vs. 6× Rotovaps — Full Operational Comparison
⚡ Energy Consumption
Ethanol requires approximately 700 watt-hours per gallon to evaporate under real-world conditions.
To recover 25 gallons per hour:
- ✅ AV15 power usage: ~17.5 kW
- ❌ Six 50L rotovaps @ 6,400 watts each = 38.4 kW
📊 Annual Energy Cost (2,000 hrs/year @ $0.12/kWh)
| System | Power Load | Annual Energy Cost |
|---|---|---|
| AV15 | 17.5 kW | $4,200 |
| 6 Rotovaps | 38.4 kW | $9,216 |
| Annual Savings | — | $5,016 |
👷 Labor Requirements
| System | Operators | Annual Labor Cost (@ $25/hr) |
|---|---|---|
| AV15 | 0.5 | $25,000 |
| 6 Rotovaps | 2.5 | $125,000 |
| Annual Labor Savings | — | $100,000 |
🛠 Maintenance & Downtime
| System | Maintenance Risk | Annual Cost (Est.) |
|---|---|---|
| AV15 | Low (stainless steel, CIP) | ~$1,000 |
| Rotovaps | High (glass, manual cleaning) | ~$3,000 |
💵 Facility Space Cost
Assuming production space costs $100/sq. ft./year:
| System | Indoor Sq. Ft. | Annual Space Cost |
|---|---|---|
| AV15 | 6.7 | $670 |
| Rotovaps | 90 | $9,000 |
| Annual Savings | — | $8,330 |
🔥 Total Annual Operating Cost
| Cost Category | AV15 (0.5 operator) | 6 Rotovaps | Annual Savings |
|---|---|---|---|
| Energy | $4,200 | $9,216 | $5,016 |
| Labor | $25,000 | $125,000 | $100,000 |
| Maintenance | $1,000 | $3,000 | $2,000 |
| Facility | $670 | $9,000 | $8,330 |
| Total OpEx | $30,870 | $146,216 | $115,346 |
💸 Capital Investment
| System | Equipment Cost |
|---|---|
| AV15 (Turnkey) | ~$97,680 |
| 6× Rotovaps Setup | ~$186,630 |
🧠 ROI Summary
| Metric | AV15 | 6× Rotovaps |
|---|---|---|
| CapEx | $97,680 | $186,630 |
| Annual OpEx | $30,870 | $146,216 |
| Year 1 Total Cost | $128,550 | $332,846 |
| Annual Throughput | 50,000 gallons | 48,000 gallons |
| Cost per Gallon (Y1) | $2.57/gal | $6.93/gal |
🏁 Bottom Line
| ✅ AV15 Advantages | ❌ Rotovap Disadvantages |
|---|---|
| 3× cheaper to run | High energy consumption |
| 80% less labor | 2–3 full-time operators required |
| Over 90% less floor space | Large, inefficient footprint |
| Stainless steel + CIP = low risk | Fragile glass + messy cleaning |
| Lower CapEx, faster ROI | Higher CapEx, slower throughput |