Rotary evaporators — rotovaps — are one of those pieces of equipment that look intimidating until you use one, and then you wonder how you ever did solvent removal without it. They're faster than simple distillation, gentler on your product, and they let you recover your solvent for reuse instead of boiling it off into the hood.
We sell rotovaps from 2L up to 50L. Here's what to know before you buy.
How a rotovap actually works
Your sample goes in the evaporating flask, which clips onto the rotary motor. The flask spins in a heated water bath, coating the inside walls with a thin film of liquid. Meanwhile, a vacuum pump reduces the pressure, which drops the solvent's boiling point. The solvent evaporates at a lower temperature than it normally would, travels up into the condenser, gets chilled back into liquid, and drips into the collection flask.
The rotation is what makes it work so well. That thin film on the flask walls has way more surface area than a static pool of liquid, so evaporation happens fast without cranking the heat.
What size do you actually need?
Flask size doesn't equal working capacity. You should only fill the evaporating flask about 40-50% full to allow the film to form properly and prevent bumping. So a "5L rotovap" really handles about 2-2.5L per run.
2L: Small-batch R&D, teaching labs, analytical prep. Fits on a standard bench, doesn't need much infrastructure.
5L: The most popular size we sell. Handles routine lab work with decent throughput. Big enough to be useful, small enough to be practical.
10L: This is where you'll want motorized lift — lowering a 10L flask full of liquid by hand gets old fast and gets dangerous eventually. Good for labs running multiple batches a day.
20L and 50L: Production equipment. You'll need dedicated floor space, a proper chiller, a bigger vacuum pump, and someone who knows what they're doing. But if you're processing volume, the per-liter cost of solvent recovery drops significantly at these sizes.
Features worth paying for
Motorized lift. On anything 10L and up, this isn't optional. Even on a 5L, it's a nice convenience if you're running back-to-back batches all day.
Digital speed and temperature controls. You need to adjust rotation speed for different solvents, and precise bath temperature matters for clean separations. Analog dials work, but digital controls give you repeatability.
PTFE vacuum seals. The rotating seal is the part that wears out. PTFE (Teflon) seals hold up well against most solvents and maintain vacuum longer. Make sure replacement seals are easy to source for whatever model you buy — you will need them eventually.
Don't forget the supporting gear
A rotovap by itself doesn't do much. You also need:
A vacuum pump — diaphragm pumps are popular for rotovap use because they're oil-free and chemical-resistant. A rotary vane pump pulls deeper vacuum but requires oil changes.
A recirculating chiller to cool the condenser. Running tap water works in a pinch but wastes water and can't reach the cold temperatures you need for volatile solvents. A chiller set to -10°C to -20°C handles most situations.
A cold trap between the rotovap and pump. Catches stray vapor, protects your pump. Worth every penny.
What we carry
The Across International SolventVap series is our most popular line — available from 2L to 50L with motorized lift on larger models, digital controls, and PTFE seals. The 5L and 10L are our top sellers.
BVV rotovaps are built with extraction workflows in mind and come as complete packages ready to run.
Not sure which size or brand fits? Call us at (458) 836-8002 or email info@highdesertsci.com. We'll help you figure it out.