What the Chiller Actually Does in Hydrocarbon Extraction
In butane/propane extraction — the hydrocarbon method used across cannabis concentrate production — the cooling system has two jobs: it subcools the liquid solvent so it stays reliably liquid and flows at a predictable rate, and it condenses solvent vapor back to liquid during recovery so you reclaim and reuse it. Both depend on hitting roughly −65°F (−54°C) at the solvent.
Subcooled solvent gives more consistent extraction, better terpene preservation, and faster, more complete recovery — which directly affects how much expensive solvent you lose per run.
Why Systems Are Paired (SLT + ULT)
Reaching and holding deep subcooling at production rates usually takes two stages working together: a Super Low Temp (SLT) condensing unit handling the bulk load, paired with an Ultra Low Temp (ULT) subcooler that pushes the solvent the last stretch to −65°F. The pairing is what lets the system keep up when both extraction and recovery are running.
How Capacity Is Rated
Capacity is solvent mass flow rate, not biomass throughput. A system rated for "300 lbs/hr" means 300 lbs of solvent per hour, not 300 lbs of plant material.
| Configuration | Solvent throughput |
|---|---|
| AG4000-SLT + AG1000-ULT | 90 lbs/hr (1.5 lbs/min) |
| AG5000-SLT + AG2000-ULT | 210 lbs/hr (3.5 lbs/min) |
| AG10000-SLT + AG5000-ULT | 420 lbs/hr (7 lbs/min) |
| AG15000-SLT + AG5000-ULT | 600 lbs/hr (10 lbs/min) |
Selecting the Right Combination
Start from your target solvent flow rate in lbs/min, then pick the SLT condensing unit that handles that load and the ULT subcooler that holds −65°F at that rate. Undersizing here doesn't just slow you down — warm solvent means inconsistent extraction and higher solvent loss on every run.
What to Specify Before You Buy
- Solvent (butane, propane, or a blend) and the subcool target — commonly around −65°F (−54°C).
- Solvent mass-flow rate you need to recover/subcool — this, not biomass, sets capacity.
- Recovery load, not just pre-cool — the chiller must handle the full cycle.
- Hazardous-environment requirements for your room classification.
- Ambient conditions — size for the hottest day.
Common Mistakes
- Sizing for pre-cool only. Solvent recovery adds load the chiller must carry too.
- Undersizing the subcool stage. If the solvent isn't cold enough, yield and recovery suffer.
- Ignoring ambient. Air-cooled capacity drops on hot days — design for the worst case.
FAQ
SLT, ULT, or a paired system?
Hydrocarbon recovery and subcooling to −65°F typically pairs an SLT unit with a ULT unit. The right combination depends on your target solvent flow rate — we'll match it.
What does the rated capacity mean?
For these systems, capacity is expressed as solvent mass-flow (e.g., lbs/hr) at the target temperature — it is not biomass throughput.
Spec a Hydrocarbon Cooling System
Tell us your target solvent throughput in lbs/min and we will spec the SLT + ULT combination that fits.