Closed-loop hydrocarbon extraction and solvent quality
Hydrocarbon extraction uses a light solvent such as butane to pull oils and aromatic compounds out of plant material. Done in a properly engineered closed-loop system, it is efficient and repeatable. The solvent you feed it sets the ceiling on how clean the result can be.
Updated November 12, 2026 · First published July 14, 2020 · Puretane
What closed-loop extraction means
In a closed-loop system the solvent stays inside sealed, pressure-rated equipment for the whole cycle. Liquid solvent passes through the plant material, carries the extracted compounds into a collection vessel, and is then recovered and condensed so it can be reused. Little or no solvent is released into the room.
Why open-loop is not an option
Open-loop methods vent butane into the air. Butane vapor is heavier than air, collects in low spots and ignites easily, which is why open-loop extraction has caused fires and explosions. It should not be done. Commercial extraction belongs in a permitted facility, using engineered equipment and the ventilation, gas detection and fire protection your local fire code requires.
Why solvent quality matters
Whatever is in the solvent can end up concentrated in the extract. That makes these numbers on the solvent's Certificate of Analysis worth checking:
- Purity and composition: the n-butane share and what the rest is (isobutane, propane, pentanes).
- Sulfur: sulfur compounds and odorants add smell and off-flavors.
- Moisture: water can freeze in lines and carry contaminants.
- BTEX: aromatic compounds you do not want in a solvent.
- Residue: oils from cans, valves or dirty transfer lines.
Choosing n-butane or a blend
Straight n-butane runs at lower pressure and evaporates more slowly; adding propane raises pressure and speeds evaporation. Many operators run a 70/30 n-butane/propane blend or a custom ratio. Compare them in n-butane vs. isobutane vs. propane blends, and always stay within your equipment's ratings.
Extraction-grade butane from Puretane
Puretane supplies extraction-grade 100% n-butane, lab-tested at 99.68% with sulfur, moisture and BTEX below detection, plus 70/30 and custom blends, in cylinders with CGA-555 liquid valves. We ship by the pallet across the US and Canada. Request a quote.
Frequently asked questions
What is closed-loop hydrocarbon extraction?
An extraction process where the solvent stays inside sealed, pressure-rated equipment and is recovered and reused instead of being vented.
Why is open-loop extraction dangerous?
It releases butane vapor into the room, where it can collect and ignite. It should not be done.
What solvent specs matter most?
Purity and composition, sulfur, moisture, BTEX and residue, all reported on a lot-specific Certificate of Analysis.