Apeks Fabrication
14381 Blamer Rd 
Johnstown OH 43031

Creating Value for our Fabrication Partners since 2001

Supercritical and Critical Point Drying


Critical Point Drying Systems

Apeks Fabrication's flagship supercritical CO2 essential oil extraction systems are the foundation for our Critical Point Drying (CPD) equipment. CPD is used during the manufacturing of aerogels, MicroElectroMechanical Systems (MEMS), silicon wafer coating processes, and other applications where the surface tension forces related to evaporation of a liquid are detrimental to the delicate surface structures of the product.  CO2 is an excellent choice as a supercritical fluid due to the fact that it is widely available, inert and has a low critical point (31C and 1072psi).  

Apeks Fabrication's CPD equipment takes advantage of Apeks' proprietary Valveless Expansion Technology, CO2 recirculation and recovery capabilities, and the product separation features to allow for safe, efficient and effective critical point drying.  

Process:1500-5L and 1500-20L operate in the sub-critical and supercritical CO2 range
  • Critical point drying typically follows the following steps:
    • Product is grown or developed in a carrier fluid like acetone or methanol
    • The product is inserted into the drying vessel while immersed in the intermediate fluid
    • The intermediate fluid is replaced with liquid CO2 
    • The liquid CO2 is heated and/or pressurized to transition the liquid into a supercritical fluid
    • Pressure is decreased while temperature is held above 31C
    • Pressure is slowly released and the product is allowed to cool
    • Product is removed from the drying vessel
Benefits of Apeks Fabrications CPD systems:
  • Large vessel sizes available (up to 5.75" diameter - custom vessels available).
  • Manual or automatic operation available.
  • Full recovery of carrier or intermediate fluid possible.
  • Built in hoist for controlled raising and lowering of product into drying vessel.
  • Utilizes Apeks' existing CO2 recirculation and recovery to reduce equipment lead times and increase reliability.
  • Effective - Drying vessel has built in filters to prevent nanowires or nano particles from entering the rest of the system.  Filters also act as a liquid CO2 dispersant to avoid exposing product to solid streams of CO2.  User selectable flow in top or bottom of drying vessel is standard.
  • Safe - All vessels are designed and manufactured in accordance with ASME specifications and pressure ratings.  Dual, redundant safety features protect the system from accidental overpressurization.  Tubing connections are made with proven compression fitting technology - the same fittings are used on aircraft and off-shore oil platforms.  Non-isolable pressure gages are on each pressure containing vessel for visual verification of depressurization prior to opening.
  • Environmentally friendly - System recirculates CO2 during extraction and allow for recovery of CO2 after extraction is complete.
  • Easy to clean - All stainless steel construction.  Vessels have polished interiors and quick opening/closing mechanisms.  All tubing can be removed and re-assembled for thorough cleaning. Separators/collection vessels use FDA sanitary fitting and connections.
  • Reliable - VET (Valveless Expansion Technology) - no constrictions or regulating valves to cause clogging of the system and loss of production time. 
  • Efficient - Regenerative heat transfer significantly reduces overall energy consumption.  Jacketed vessels and water recirculation allow for capture and transfer of heat through drying cycle.
  • Easy to understand - open frame design and visual indication of valve positions allows for easy assessment of flow paths and system configuration. No mysterious boxes with inlet and outlet connections on the outside.
  • Flexible - additional drying vessels, tables or accessories can be easily added to the system.
  • Small footprint - systems are designed to minimize space requirements - all operations occur from the front of the system.
  • Production friendly - integral weighing scale and system timer help users efficiently run their drying operations.
System Specifications:

Drying Vessel
  • Inner diameters up to 5.75"
  • Lengths up to 60"
  • Pressure - maximum pressure - 1500 psi (103 bar)
  • Temperature - max 200F (93C)
  • Materials - 304 stainless steel except closure bolts which are zinc coated grade 8 steel.  Vessel interior is polished to food grade level.
  • Closures - ASME flange, both ends with integral hinges 
  • Sealing mechanism - self energized o-ring seals
  • Filter - integral filters on flanges. 20 micron standard, other sizes available.
  • Temperature measurement - internal K type thermocouple senses internal drying temperature
  • Drying vessel is jacketed for temperature control
  • Safety - non-isolable spring loaded safety relief valve prevents accidental over-pressurization
  • Custom vessels also available - just ask!
CO2 Recirculation Pump
  • Flowrate - up to 25 CFM gas flow
  • Construction - pneumatically driven, dual piston type
  • Materials - all wetted parts are 316 stainless steel
  • Filter - coalescing filter on inlet to prevent oil introduction
  • Safety - non-isolable spring loaded safety relief valve prevents accidental over-pressurization
Carrier fluid collection vessels - 
2 collection vessels standard on each unit.  1st collection vessel volume is adjustable for varying amounts of liquid collection
  • Volume: 2.5 Liters per separator  
  • Pressure - Maximum pressure - 500 psi (34 bar)
  • Temperature - up to 200F (93C)
  • Materials - all 304 stainless steel 
  • Closures - FDA sanitary style bolted
  • Sealing mechanism - sanitary gasket 
  • Safety - non-isolable spring loaded safety relief valve prevents accidental over-pressurization
Separation Mechanism
  • Valveless Expansion Technology (VET) - flow path from drying vessel to 1st collection vessel is continuous diameter with no constrictions.  Separation of carrier liquid occurs in 1st separator utilizing centrifugal separation and CO2 depressurization.  
Heat Exchangers 
  • Construction - tube in tube style
  • Materials - all 304 stainless steel
  • Cooling/Heating media - Regenerative HX is CO2, Temperature Control HX is water or water/glycol mix
  • Recirculating chiller/heater
  • Temperature range: -10C to 80C (14F to 176F)
  • Flow rates up to 3GPM
  • Materials - all 304 stainless steel 
  • Weighing - integral weighing system for CO2 with tare and zeroing 
  • Integral air driven or electric hoist for controlled raising/lowering of product cartridges
Control System
  • Input - 110V, 15A
  • Functions - user programmable timer displays set time and run time
  • Safety - pressure transducers monitor system pressure and shut down system to prevent accidental over-pressurization
  • Optional - Data acquisition 
  • Optional - Fully automated system complete with pneumatic actuated valves and programmable user interface
System Requirements
  • Compressed Air - minimum 65 SCFM clean, dry air regulated to 150 psi or less.  
  • Extractor Electrical - 115V AC, 60 hz, 15A
  • Chiller/Heater Electrical - 220V AC, 1 phase, 60 hz, 15A
  • CO2 - Gaseous CO2 with dip tube