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PDF DownloadImage Gallery K850 Critical Point Drier

  • K850 Critical Point Dryer
  • Standard specimen holder
  • Standard specimen holder - ready to load
  • Porous specimen pots for small or delicate specimens
  • Flow Meter (Optional)

arrow11K850 Critical Point Dryer with Thermoelectronic Heating and Adiabatic Cooling

The K850 Critical Point Dryer is designed for use with CO2, having first replaced any water in the specimen by a series of dehydration, often in the same fluid such as Acetone, which will also be the intermediate fluid.

(Wet Specimen) – Water – Acetone – 30% – 100% – CO2 – C.P.D. – (Dry Specimen)

The specimens for critical point drying are located in the pressure chamber of the K850. The chamber is pre-cooled to allow it to be readily filled with liquid CO2 from a gas cylinder. The chamber is then heated to just above the critical temperature with subsequent critical pressure being achieved. The CO2 gas is vented through a needle valve, to avoid specimen distortion.

The K850 is fitted with thermoelectronic Heating and Cooling and Temperature control of +5°C on Cooling, and +35°C on Heating. This ensures the critical point is accurately obtained, avoiding excess pressures or temperatures, or the need to rely on pressure relief valves to control pressure during the heating cycle. The chamber is vertical, with top loading, to ensure specimens do not become uncovered during the drying process, with a side viewing port to locate the miniscus for the correct level when initially filling the chamber.

The K850 is fitted with a fine let down needle as standard and flow gauge is no longer required. A separate flow meter is available if your application requires highly accurate monitoring and/or flow control.


  • Vertical chamber with top filling and bottom draining
  • Normal operating temperature 35°C pressure 1500 psi
  • Thermoelectric Peltier cooling and heating
  • Fine control needle valve pressure letdown
  • Illuminated chamber with side viewing port and protective 'Lexan' shield
  • Stirrer system for enhanced solvent exchange
  • Temperature monitoring and control with thermal cut-out protection
  • Pressure monitoring with pressure relief valve and rupture disc protection
  • Polycarbonate safety shield


Instrument Case 450mm (W) x 350mm (D) x 175mm (H)
Weight 12Kg
Specimen Chamber 32mm(Dia) x 47mm (height)
(Tested to 3000 psi)
Temperature Gauge 0-120°C
Thermal Cut-Out 40°C
Pressure Gauge 0-3000 psi
Pressure Relief At 1500 psi
Rupture Disc At 1900 psi
Peltier Cooling/Heating +5°C to +35°C
Two On/Off Valves Inlet/Outlet/Cool/Vent
Needle Valve Letdown
Supply 115V 60Hz (6 Amp Max)
230V 50Hz (3 Amp Max)
Services Requires CO2 gas cylinder direct connection
by high pressure hose. (High pressure hose
included with instrument.)

Ordering Information

91090 K850 Critical Point Dryer complete POR Quote
Replacement Parts
91091 Mesh Basket each 250.00 Add to Cart
91092 Porous Spec Pots 10/pk 170.00 Add to Cart

Technical Data sheet

Critical Point Drying Principles

PDF DownloadImage GalleryK850 Critical Point Drierarrow11K850WM Large Chamber Critical Point Dryer

The K850WM is compact, benchtop instrument designed to critical point dry a complete 150mm/6" wafer. A convenient wafer holder allows rapid transfer and ensures that pre-drying does not occur.

The K850WM has built-in heating and water cooling using the E4860 Recirculating Heater/Chiller. This combination will give temperature control of +5°C cooling and +35°C during heating. This ensures the critical point is accurately obtained, avoiding excess pressures or temperatures, or the need to rely on pressure relief valves to control pressure during the heating cycle.

The K850WM has a vertical chamber which allows top-loading of specimens. A viewing port is fitted in the top plate for specimen observation. The specimen exchange mechanism is simple to use and ensures the specimen remains under liquid during loading.


  • 170mm diameter chamber - optimized for wafer/MEMS drying
  • Vertical chamber with top-loading and bottom draining - ensures specimens do not become uncovered during drying
  • Thermoelectric heating - accurate temperature control
  • Fine control needle valve pressure let down - precise control
  • Temperature monitoring and control with thermal cut-out protection
  • Pressure monitoring with safety cut-out for over pressure
  • Three-year warranty

Specimen handling

100mm or 150mm diameter wafers are held in a PTFE holding tray. The tray including wafer is immersed in acetone in order to remove all moisture from the specimen. After dehydration, the wafer and holder are transferred into the pre-cooled specimen chamber using the wafer transfer device. On completion of the critical point drying process, the wafer is removed from the chamber using the transfer device prior to further processing.

Ordering Information

91090-WM K850WM Large Chamber Critical Point Dryer   POR Quote


E4860 Recirculating Heater/Chiller (for cooling chamber)   POR Quote
E3102 Carbon Dioxide bottle heating system   POR Quote

For our Critical Point Dryer Accessories

Technical Data Sheet

Critical Point Drying Principles

PDF DownloadImage GalleryE3100 Critical Point Dryer

  • E3100 Critical Point Dryer
  • E3100 Critical Point Dryer, with specimen holder, tool kit and CO2 transfer hose
  • E3100 specimen 'boat' – with nine specimen holders
  • E3100 specimen holder for microscope cover slips
  • Holder for 3.05mm TEM grids
  • Porous specimen pots for small or delicate specimens
  • E3000 component parts
  • Critical point drying phase diagram
  • E3100 Kit
  • E3000 Service Kit
  • E3100 Service Kit

arrow11E3100 Critical Point Dryer

Where increased chamber volume is required, for either size or quantity of specimens to be dried, the large capacity model E3100 is available. The chamber dimensions are 63.5mm internal diameter x 82mm in length, giving approximately three times the volume of the E3000. The transfer boat will also accept three times the number of specimen baskets.


  • Proven reliability – over 6,000 critical point dryer installations world-wide
  • Simple robust construction – easy to maintain (there are no electrical components) – many critical point dryer users carry out their own routine maintenance
  • Horizontal chamber and large viewing window – excellent visibility of the fluid level and drying process
  • Large robust valves for draining of fluids, ingress of liquid CO2 and venting of gas – the rapid ingress of CO2 helps prevent pre-drying of specimens
  • Safety – the design has been independently type tested to proof pressures in excess of the working pressure and bursting disc rupture pressure. A pressure bursting disc is also fitted to safeguard against misuse
  • Specimen handling – optional specimen holders for microscope coverslips and TEM specimen grids. Porous pots are available for fragile or very small specimens
  • Three-year warranty

Temperature control

Dial gauges display pressure in the chamber and the temperature of water circulating through the jacket. Three pressure valves permit easy connection to the liquid CO2 cylinder and allow liquid agitation and venting of the chamber. A source of hot running water is essential. Cooling is also useful, especially for sequential process runs or in hot climates.

The temperature of the E3100 chamber is raised with a hot water supply. Mains water can be used but a more elegant method involves the use of the optional E3500 Thermocirculator, which is connected directly to the inlet and outlet of the water jacket. The temperature of the circulatory fluid can be pre-set (eg at 37°C, just above the critical temperature).

A second alternative is the model E4860 Recirculating Heater/Chiller, which can be used to pre-cool the chamber to below ambient prior to loading specimens and then to heat the chamber to the critical temperature.


Safety is, of course, an important consideration with all pressure vessels. Should critical pressure and temperature be inadvertently exceeded, a bursting disc is incorporated in the chamber support. The critical point drying chamber itself is tested to 2,500psi, which is approximately twice the working pressure. A guard is also fitted over the viewing window.

E3100 Specimen Boat
E3100 Specimen Boat

Specimen holder (boat)

An important feature is the design of the transfer boat. This permits specimens in the intermediate fluid to be transferred to the critical point dryer. On sealing the chamber, the intermediate fluid begins to drain and can be replaced with liquid CO2. In this way the specimens are never allowed to dry out during the specimen loading and transfer stage of the process.

The E3100 is supplied with a standard tissue holder (boat). The E3100 is supplied with the E3100-01 tissue boat and has three slots each with three tissue baskets, making a total of nine tissue baskets. Other choices of holders are listed below under Options and Accessories.

Bonded chamber seals – Nitrile or EPDM?

E3100 is fitted with a standard with nitrile bonded window and door seals. Nitrile is a good general material due to its ability to withstand attack by solvents, such as ethanol. However, if acetone is used as the transition fluid then the EPDM seals have been found to be more resistant to chemical attack by that solvent.

If you are ordering an E3100 and are planning to use acetone as the transition fluid, please state this on the order and EPDM bonded seals will be fitted.

For existing instruments, both Nitrile and EPDM bonded seal can be ordered as spare parts.

Glass microscope coverslip holder
Glass Microscope Coverslip Holder
CPd Porous Pots
Porous Pots
CPD TEM grid holder
TEM Grid Holder
E3500 Thermocirculator
E3500 Thermocirculator
E4800 Recirculating Heater Chiller
E4800 Recirculating Heater Chiller
CPD TEM grid holder
E3000 Service Kit
CPD TEM grid holder
E3100 Service Kit

Options and Kits

Glass microscope coverslip holder (option): Specially adapted boats allow glass coverslips to be held firmly during drying. The E3000-02 is designed for the E3000 and has a maximum capacity of seven coverslips. Likewise, the larger E3100-02 coverslip boat is available for the E3100 'Jumbo' Critical Point Dryer and has a carrying capacity of 21 coverslips.

TEM grid holder (option): The E3000-1 holder for 3.05mm grids and the E3000-2 grid holder for 2.3mm grids can be used with all Electron Microscopy Sciences critical point dryers. Maximum number of grids is three.

Porous pots with lids (option): EMS 800A solvent-resistant porous pots (12.7mm x 15.5mm) with lids are ideal for very small or very delicate specimens.

Service Kits:

Service kits are available for both the E3000 and E3100; see the ordering table below. Please call our service department for specific questions.

For the E3000 (NOTE: E3000-01 is included as standard):

  • E3000-1 Specimen holder for 3.05mm grids
  • E3000-2 Specimen holder for 2.3mm grids
  • E3000-01 Specimen holder for tissue (boat)
  • E3000-02 Specimen holder for coverslips
  • EMS 800A Porous pots with lids 12.7mm x 15.5mm (pack of 10) for micro-specimens
  • E3500 Thermocirculator for control of heating cycle
  • E4860 Recirculating Heater/Chiller to control heating and cooling cycle (please specify voltage)

For the E3100 (NOTE: E3100-01 is included as standard):

  • E3100-1 Specimen holder for 3.05mm grids
  • E3100-2 Specimen holder for 2.3mm grids
  • E3100-01 Specimen holder for tissue (boat)
  • E3100-02 Specimen holder for coverslips
  • EMS 800A Porous pots with lids 12.7mm x 15.5mm (pack of 10) for micro-specimens
  • E3500 Thermocirculator for control of heating cycle
  • E4860 Recirculating Heater/Chiller to control heating and cooling cycle (please specify voltage)

Site Requirements

Site selection: The apparatus should be positioned in the laboratory with convenient access to:

  • Hot and cold water supply (if the optional E3500 Thermocirculator or E4860 Recirculating Heater/Chiller are not used)
  • Mains power supply (for E3500 and E4860 only)
  • Fume cupboard or window, or an area of good ventilation
  • Space for CO2 siphon cylinder

CO2 Cylinder: The E3000 and E3100 require a cylinder of liquid CO2 fitted with a siphon tube (indicated by a vertical white stripe on the cylinder). If there is any doubt regarding the presence of a siphon tube, advice should be sought from the gas supplier.

Cylinder connection threads vary from country to country and even between manufacturers in the same country. For example, the transfer pipe supplied is fitted with ¼" British Standard Pipe (BSP) and 0.86" x 14 TPI union. These are standard threads for the UK and generally in the rest of the world, but will not fit cylinders in the USA.

An E3000-US kit should be specified for use within the USA; this includes a transfer pipe adaptor which will fit USA cylinders. If it is deemed necessary to fabricate another transfer pipe, advice should be sought from a local supplier of high-pressure fittings.

Heating and cooling: Use a mixer to the laboratory hot and cold water outlets, terminating with a 6mm/¼" hose connection for the PVC tubing supplied. A 'Y' piece connected to the hot and cold water taps is also suitable. The E3000 and E3100 require both hot and cold water during the operating cycle. Cooling facilitates filling of the work chamber with liquid CO2, and heating is required to take the liquid above its critical point.

Good control of the water temperature is essential for good results, hence the recommended use of the E3500 Thermocirculator or, more conveniently, the E4860 Recirculating Heater/Chiller which gives precise control of cooling and heating.

Space requirement: A minimum bench space of approximately 230 x 230mm is required.

Ordering Information

E3100 Large Chamber Critical Point Dryer
Chamber dimensions: 63.5mm Ø x 82mm length
Supplied with:
- E3100-01 Specimen holder for tissue (boat)
- 1m liquid CO2 delivery tube
- O ring and L gasket set (including window and door bonded seals)
- Spare bursting disc and retaining copper (Cu) washer
- Steel bar for tightening/untightening the door
- Flat wrench (for removing the window retaining ring)
- Comprehensive manual
- Pressure test certificate
E3000-061 Service Kit for E3000 Quote
E3100-061 Service Kit for E3100 Quote

Technical Data Sheet

Critical Point Drying Principles

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