CO2 Supercritical Co-Solvent Tank Selection
CO2 Supercritical Co-Solvent — Bulk Tank Selection at Cannabis and Hemp Supercritical-CO2 Extraction, Botanical Co-Extract Service, and Hydrocarbon Co-Solvent Staging
CO2 supercritical co-solvent (ethanol Formula 3A + n-propane food-grade + n-butane food-grade + isobutane + dimethyl-ether food-grade modifier blend used at 1-15 weight-percent dosing in supercritical-CO2 extraction at 31C critical temperature and 73.8 bar critical pressure baseline; co-solvent CAS 64-17-5 ethanol + 74-98-6 propane + 106-97-8 butane + 75-28-5 isobutane; supercritical CO2 itself CAS 124-38-9 at sub-zero compressed-liquid + supercritical-fluid phase) is the integrated co-solvent chemistry envelope at North American supercritical-CO2 cannabis + hemp + nutraceutical botanical-extract service. Storage envelope at the co-solvent + recovered-modifier side is concentrated at HDPE atmospheric day-tank service for ethanol modifier staging plus DOT-MC-331 + ASME pressure-vessel + UL-listed propane/butane storage at the hydrocarbon co-solvent side.
U.S. and Canadian supercritical-CO2 extraction throughput is concentrated at licensed cannabis processors (Nuvata, Apeks Supercritical, Eden Labs, Vitalis Extraction Technology, MedPharm, Ananda Hemp, BlueSky Bio Analytical) plus industrial hemp cannabinoid extraction operations (Folium Biosciences, Open Book Extracts, Treetop Biopack, ABRcanna, Beam Cannabis, Mile High Labs predecessor operations) plus nutraceutical botanical-extract operations (kava, kratom, valerian, milk-thistle, echinacea, turmeric, mushroom, ginseng, hops, hemp). Storage envelope is concentrated at HDPE 200-1,500-gallon ambient day-tank service for ethanol modifier staging combined with ASME pressure vessel storage at the supercritical-CO2 + propane + butane side.
The eight sections below cite OSHA 29 CFR 1910.106 flammable-liquid + 1910.111 anhydrous ammonia + 1910.110 LPG storage + NFPA 30 + NFPA 58 + NFPA 30A + NFPA 1 Fire Code + IFC Chapter 53 + IFC Chapter 57 + DOT 49 CFR 173 + ATF 27 CFR 19/20 + USDA 7 CFR 990 + DEA 21 CFR 1308 + state cannabis-regulator framework + ASME Boiler and Pressure Vessel Code Section VIII + ICH Q7 + cGMP 21 CFR 211 + routine operating practice at North American licensed CO2-extraction cannabis + hemp + botanical service.
1. Material Compatibility Matrix
The CO2 supercritical co-solvent envelope is a multi-phase engineering problem: supercritical CO2 itself at 73.8 bar + 31C requires ASME pressure-vessel construction (HDPE not specified at SCFE reactor service); ethanol modifier at ambient atmospheric staging is HDPE-acceptable at static-bonding-grade construction; propane + butane + dimethyl-ether co-solvent require ASME + DOT-MC-331 + NFPA 58 listed pressure storage. HDPE day-tank application at this envelope is restricted to ambient ethanol modifier staging only.
| Material | Ethanol modifier @ ambient | Liquid CO2 @ -20C 20 bar | Propane/Butane @ ambient ASME | Notes |
|---|---|---|---|---|
| HDPE rotomolded | A | D | D | Acceptable at ambient ethanol modifier ONLY; not specified at CO2 or LPG |
| XLPE rotomolded | A | D | D | Same envelope as HDPE |
| 316L stainless steel | A | A | A | Standard at SCFE reactor + cryo CO2 receiver + LPG ASME tank service |
| 304 stainless steel | A | A | A | Acceptable at non-chloride service; 316L preferred at cGMP |
| Carbon steel ASME pressure | B | A | A | Standard at LPG horizontal ASME + UL-listed CO2 receiver |
| FRP (vinyl ester) | B | D | D | Acceptable at ambient ethanol; not specified at pressure vessel service |
| PVDF (Kynar) | A | B | C | Premium at ambient + cold ethanol; check spec at cryo CO2 |
| PTFE / Teflon | A | A | A | Premium gasket + diaphragm at SCFE + cryo + cGMP |
| FEP / PFA | A | A | A | Premium tube + lining at high-purity service |
| Aluminum 5083 / 6061 | A | A | A | Acceptable at MC-331 LPG cargo tank + DOT-CO2 cylinder |
| EPDM | D | C | D | NOT acceptable at ethanol or LPG; marginal at CO2 |
| Nitrile (Buna-N) | D | D | B | Not acceptable at ethanol or CO2; acceptable at pure propane |
| Viton (FKM) | A | B | A | Standard at ethanol + LPG; verify spec at SCFE service |
| Kalrez / FFKM | A | A | A | Premium at SCFE + cGMP cleanroom |
| Brass / Bronze | B | A | B | Acceptable at LPG fittings; not preferred at ethanol |
| Copper | B | A | B | Standard at CO2 cryo line + LPG meter; ethanol service risk |
| Carbon steel uncoated | C | B | A | Pressure-vessel-grade at LPG; ethanol pickup contamination |
| Glass-lined steel | A | A | A | Premium at cGMP API-grade SCFE reactor |
The dominant industrial pattern at North American licensed cannabis + hemp + nutraceutical supercritical-CO2 extraction service is HDPE or XLPE rotomolded atmospheric ethanol modifier day-tank in the 200-1,500-gallon range at the static-bonding-grade construction, combined with ASME-listed 316L stainless or carbon-steel-pressure-vessel CO2 receiver + propane/butane LPG tank at the high-pressure side. OneSource Plastics' 5-brand HDPE network covers the ambient ethanol modifier day-tank envelope only; pressure-vessel CO2 + LPG storage is specified separately by the supercritical-CO2 system OEM (Apeks, Eden Labs, Vitalis, Waters, Thar) within their integrated extraction skid.
2. Real-World Industrial Use Cases
Cannabis Supercritical-CO2 Extraction (Adult-Use + Medical Markets). Licensed adult-use + medical cannabis processors operating supercritical-CO2 extraction across California (MedMen + Curaleaf legacy + Cresco), Colorado (Stratos + Mary's Medicinals + Wana), Oregon (Cura Cannabis legacy + Quill), Washington (Truly + Heylo), Nevada, Arizona, Massachusetts, Illinois, New York, New Jersey, and the rest of the legal-state framework operate Apeks + Eden Labs + Vitalis + MRX + Waters supercritical-CO2 skids at 70-700 bar pressure and 35-80C temperature. Storage envelope at the co-solvent side: HDPE 200-1,000-gallon ambient ethanol modifier day-tank for cold-injection at the SCFE pump head ahead of recovery-and-recycle.
Industrial Hemp Cannabinoid CO2 Extraction. Licensed industrial-hemp processors operating supercritical-CO2 extraction under USDA Hemp Production Final Rule + Health Canada framework process biomass to broad-spectrum + isolate CBD + CBG + minor cannabinoid product at multi-hundred-kilogram-per-day biomass throughput. Storage envelope: HDPE 500-2,000-gallon ethanol modifier day-tank at the warehouse pump house, plus ASME-listed liquid-CO2 storage at 20-50 ton bulk-CO2 tank (cryogenic Linde, Air Liquide, Air Products, Praxair-Linde supply).
Nutraceutical Botanical Supercritical-CO2 Extract. ICH Q7 + cGMP 21 CFR 211 nutraceutical and pharmaceutical botanical-extract operations (kava, kratom, valerian, milk-thistle, echinacea, turmeric, mushroom, ginseng, ashwagandha, hops, rosemary antioxidant, calendula, chamomile, lavender essential oil, citrus essential oil) operate supercritical-CO2 extraction at USP-grade + EP-grade + ICH-Q7 botanical-feedstock framework. Storage envelope: 316L stainless preferred at full-cGMP operations; HDPE acceptable at upstream ethanol modifier day-tank at the staging side.
Hop Oil and Brewery Botanical Extract. Hop oil + hop CO2 extract production at brewery + hop-broker scale (John I. Haas, Hopsteiner, Yakima Chief Hops, Cargill, Steiner) operates supercritical-CO2 hop-cone extraction at 70-300 bar pressure with optional ethanol or propane co-solvent at sub-1% dosing. Storage envelope: 316L stainless ASME BPE preferred at food-grade + brewery-supply-chain operations; HDPE acceptable at ethanol modifier day-tank.
Specialty Food and Flavor Supercritical-CO2 Extract. Coffee decaffeination (Swiss Water, Mountain Water, KVW Coffee Tech), spice + essential-oil + flavor extraction (McCormick, ADM Decaf, Givaudan, Symrise, IFF, Firmenich), and specialty-food supercritical-CO2 extraction operate at the same envelope. Food-grade or USP-grade ethanol + propane modifier dosing is standard at sub-5% weight-percent for selective compound extraction. Storage envelope: 316L stainless ASME BPE preferred at full FDA cGMP + 3-A Sanitary operations; HDPE acceptable at ethanol modifier day-tank service.
Lab-Scale Supercritical-CO2 Extraction Research. University and contract-research-organization analytical-scale supercritical-CO2 extraction (UF, OSU, NCSU, Purdue, UCSD, Cornell, FAU, USC, Texas Tech, Colorado State, Oregon State, Washington State) operates Apeks + Eden Labs + Waters bench-scale + pilot-scale skids at sub-50-gallon batch capacity. Storage envelope: 50-200-gallon HDPE ambient day-tank or USP-grade carboy ethanol modifier holding at the bench-scale side.
3. Regulatory Framework
OSHA 29 CFR 1910.106 + 1910.110 + 1910.111 Hazardous-Liquid Storage. OSHA Flammable and Combustible Liquids 29 CFR 1910.106 governs ethanol modifier storage; 29 CFR 1910.110 (Storage and Handling of LPG) governs propane + butane co-solvent storage; 29 CFR 1910.111 (Anhydrous Ammonia) at related ammonia carrier service. Storage-room construction + ventilation rate + explosion-proof electrical + sprinkler density apply per Class IB + Class IIIA flammable-liquid + LPG service classification.
NFPA 30 + NFPA 58 + NFPA 30A Frameworks. NFPA 30 Flammable and Combustible Liquids Code (ethanol modifier), NFPA 58 Liquefied Petroleum Gas Code (propane + butane), NFPA 30A Code for Motor Fuel Dispensing (related fuel-grade hydrocarbon dosing service), NFPA 1 Fire Code, and IFC Chapter 53 (compressed-gas storage) + IFC Chapter 57 (flammable + combustible liquids) drive the AHJ-permit framework for any supercritical-CO2 + co-solvent extraction facility.
DOT 49 CFR 173 + ATF 27 CFR 19/20. DOT 49 CFR 173 Hazardous Materials Regulations govern compressed-gas + flammable-liquid in-transit shipping (CO2 cylinder + LPG cargo tank + ethanol cargo tank). ATF 27 CFR 19/20 governs undenatured + denatured ethanol modifier permit + recordkeeping framework at any cannabis + hemp + botanical extraction operation.
USDA 7 CFR 990 + DEA 21 CFR 1308. USDA Hemp Production Final Rule (2018 Farm Bill 7 CFR 990) governs licensed industrial-hemp cultivation + processing (THC delta-9 less-than-0.3% testing, USDA-approved or state-equivalent regulator licensing, recordkeeping retention). Federal cannabis (THC delta-9 greater-than-0.3%) remains Schedule I under DEA 21 CFR 1308; state cannabis-regulator framework operates without federal preemption challenge through current rescheduling discussion.
State Cannabis Regulator Framework. CA DCC, CO MED, WA WSLCB, OR OLCC, NV CCB, AZ DHS, MA CCC, IL IDFPR, MI MRA, NJ CRC, NY OCM, MD MMCC, VA Cannabis Control Authority, MO DCR, MN Office of Cannabis Management, OH Division of Cannabis Control + state-level testing-laboratory + chain-of-custody + tax-stamp framework drive operational compliance at any state-licensed CO2-extraction facility.
ASME Boiler and Pressure Vessel Code Section VIII. SCFE pressure vessels (extractor + separator + receiver + recovery-recycle vessel) operate under ASME Section VIII Division 1 or 2 design, fabrication, inspection, and stamping framework. Pressure-relief device sizing per API 520/521 + ASME PTC 25 + facility AHJ review at every commissioning + 10-year recertification interval.
cGMP 21 CFR 211 + ICH Q7 at Pharmaceutical-Grade Operations. FDA Current Good Manufacturing Practice 21 CFR 211 + ICH Q7 GMP for APIs framework apply at FDA-registered pharmaceutical or nutraceutical CO2-extraction operations. ASME BPE Bioprocessing Equipment standard drives 316L stainless surface-finish + cleanability + drainability + sterility specification at the SCFE reactor side.
EPA SPCC and Stormwater Framework. Cannabis + hemp + botanical CO2-extraction sites with bulk ethanol modifier storage exceeding 1,320-gallon aggregate threshold require Spill Prevention, Control, and Countermeasure (SPCC) plans under 40 CFR 112; concurrent industrial stormwater permitting under 40 CFR 122 multi-sector general permit applies at most processing sites.
4. Storage System Specification
Ethanol Modifier Day-Tank (HDPE Atmospheric Service). SCFE-skid ethanol modifier day-tank at HDPE rotomolded 200-1,500-gallon scale: HDPE resin per ASTM D1248 specification with conductive carbon-black additive at static-discharge service; vertical flat-bottom or conical-bottom vessel; 3-inch ANSI flanged top fill with grounded camlock dry-disconnect; 2-inch flanged bottom outlet with bonded ball valve; conservation vent with flame arrestor sized per NFPA 30 + API 2000; 18-inch top manway for inspection; ultrasonic level transmitter with high-high alarm; static bonding strap to facility ground grid; sample valve at 12 inches above bottom outlet; integration with metering pump + check valve + pressure transmitter ahead of the SCFE pump suction.
Liquid CO2 Bulk Storage (ASME Pressure Vessel). Bulk liquid-CO2 storage at 20-50 ton (44,000-110,000-pound) capacity scale: vacuum-insulated ASME pressure vessel rated at 350-500 psi MAWP; cryogenic vaporizer + super-heater + downstream pressure-control regulator; perimeter security fence + impact protection bollard; redundant pressure-relief device sized per API 520; carbon-steel or 316L stainless construction. HDPE not specified at this service.
Propane and Butane LPG Storage (ASME + NFPA 58). Propane + butane co-solvent bulk storage at ASME-listed horizontal pressure vessel 250-3,000-gallon water capacity scale per NFPA 58 + DOT 49 CFR 173.315; UL-listed coatings + cathodic protection at outdoor installation; perimeter clearance distance per NFPA 58 Table 6.4.1.1; carbon-steel ASME construction. HDPE not specified at this service.
Recovered Co-Solvent Reclaim Holding. Post-SCFE recovered ethanol + propane + butane co-solvent reclaim cycle generates 95-99% recovered stream staged at HDPE (ethanol modifier only) or ASME-listed pressure vessel (LPG modifier) ahead of next-cycle re-use. ATF 27 CFR 19/20 + state cannabis-regulator + recovery-volume reconciliation at every batch.
Spent and Off-Spec Co-Solvent Holding. Off-spec ethanol modifier holding ahead of off-site disposition at HDPE 100-500-gallon temporary holding tank in a secondary-containment pan. Off-spec LPG modifier disposition handled via in-place ASME holding tank + DOT 49 CFR 173 + EPA RCRA framework.
5. Field Handling Reality
Handler PPE. SCFE co-solvent bulk handling: chemical-resistant gloves (nitrile or neoprene at brief contact, butyl at extended exposure) + safety glasses + face shield at any open-pour transfer + fire-resistant coverall (Nomex or equivalent FR garment) + closed-toe steel-toe footwear with anti-static sole + flame-retardant lab coat. Eye-wash station + emergency shower per OSHA 29 CFR 1910.151. Class I Div 1 explosion-proof flashlight + intrinsically-safe radio at any flammable-liquid + LPG storage area access.
Tanker Receipt and Bulk Transfer. Ethanol modifier transport: 4,500-7,500-gallon DOT-MC-307 stainless cargo tank or 250-330-gallon UN-rated IBC. Propane + butane transport: DOT-MC-331 cargo tank at LPG bulk delivery; DOT 4BA + 4BW + ICC-3AA cylinder at smaller-scale delivery. Liquid-CO2 transport: vacuum-insulated MC-338 cryogenic cargo tank from regional industrial-gas supplier (Linde, Air Liquide, Air Products, Praxair-Linde, Matheson). Off-loading at the licensed extraction facility: facility-side air-operated diaphragm or magnetic-drive centrifugal transfer pump at ethanol service; ASME-listed cargo-tank PTO or pump-back at LPG service; cryogenic transfer line + pressure-equalization vapor-return at liquid-CO2 service.
Static Electricity and Vapor Management. The dominant operating-discipline reality at any ethanol modifier transfer is static-electricity ignition risk: free-fall fill velocity must be limited to less-than-1 m/s during initial fill, with submerged fill via dip pipe terminating within 6 inches of tank bottom mandatory at any HDPE or non-conductive vessel. Conductive-grade HDPE with carbon-black additive (less-than-1E6 ohm-meter surface resistivity) is preferred. LPG transfer additionally requires ASME-listed bonded transfer hose + dry-disconnect coupling + PTO-actuated emergency shutoff valve.
Batch QC and Recovered-Solvent Reconciliation. Each modifier batch requires sample collection at receipt + at recovered-solvent reclaim cycle: ethanol proof check via hydrometer or densitometer, water content via Karl-Fischer titration, color + odor + appearance at every receipt sample. LPG modifier QC includes vapor-pressure check at 70F + gas-chromatograph composition + sulfur + olefin content per HD-5 + HD-10 specification. ATF 27 CFR 19/20 + state cannabis-regulator + cGMP 21 CFR 211 framework drives recordkeeping discipline.
Spill Response. Ethanol modifier spill response: immediately evacuate to 50-foot minimum radius; eliminate ignition sources; trained responder in fire-resistant PPE + SCBA proceeds with absorbent pads + AR-AFFF foam suppression; do not flush spill to drain; contain to secondary containment + transfer to off-site disposal via DOT-registered transporter under EPA RCRA F003 listed solvent waste manifest. LPG modifier release response: immediately evacuate downwind to 300-foot minimum radius; eliminate ignition sources; allow vapor cloud to dissipate (do not attempt to extinguish gas fire unless flow is shut off); notify facility safety officer + state cannabis regulator + DOT + LPG supplier emergency-response contractor.
Tank Cleaning and Inspection. Annual or campaign-end tank inspection: ethanol modifier HDPE day-tank drain + ventilate to less-than-25% LEL ahead of any internal entry; confined-space entry per OSHA 29 CFR 1910.146 with continuous LEL meter + supplied-air respiratory protection + standby attendant. ASME pressure vessel CO2 + LPG inspection at 5-year + 10-year ultrasonic + radiographic NDE per API 510 + ASME PCC-1 framework.
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