Hi everyone,
I’m looking for advice on diagnosing my vacuum ethanol recovery setup before I start buying upgrades.
My goal is to recover ethanol from QWET/FECO at around 30–40°C instead of 50–55°C. At 50–55°C the system works acceptably, but at 30–40°C the recovery rate becomes extremely slow.
Current performance:
Recovery rate: ~0.7–0.9 L/hour at 50–55°C
Target: 1–4 L/hour at 30–40°C
Batch size: ~15 L / 4 gallons per run
Current setup:
20 L evaporation chamber on hotplate → 1/4" JIC tubing/connectors (6mm ID, 4.3mm connector bore) → 1/4" ID condenser coil → 20 L collection chamber → vacuum pump
Pump: dual-stage diaphragm pump, 18 L/min / 0.64 CFM, rated ultimate pressure 10 mbar
Tubing/fittings: nominal 1/4", but some JIC connector bores appear to be around ~4.3 mm ID
Please excuse the somewhat rudimentary (and messy) setup:
Vacuum test results:
Pump isolated: ~-30 inHg almost instantly
Collection vessel isolated: ~-27.25 inHg after 30–60 min
Full system dry: ~-25 inHg after 30–60 min
Full system wet / evaporating ethanol: ~-24.5 inHg
My question:
Does the full system only reaching ~-25 inHg when dry point mainly toward leaks in the assembled system?
My instinct is that I should leak-test the full system first before upgrading the pump or vapour path. The likely leak points would be valves, gaskets, manifold connections, or fittings.
I also suspect the 1/4" vapour path and ~4.3 mm connector bores may be restrictive for this scale, but I’m not sure if that should be addressed before or after leak testing.
Would you prioritise:
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leak testing the full assembled system,
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upgrading the 1/4" vapour path to 3/8" or 1/2",
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upgrading the pump,
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or upgrading the vapor path and vacuum pump
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any other suggestions are warmly welcome
I’m trying to avoid buying a larger pump if the real issue is simply leaks or restrictive plumbing.