Freeze Drier and Turbo Freeze Drier

EMS 750 Freeze Drier

What is FREEZE DRYING?

The application of freeze drying for specimen preparation for TEM and SEM is a well established practice.

Its application is to reduce the distortion which occurs when a wet specimen dries by normal evaporation. This distortion is due to the forces of surface tension going from a liquid to vapor phase such as water to water vapor, commonly the situation in a Biological Specimen. However, if we freeze the specimen and maintain it frozen, then by applying a vacuum, we can obtain a situation where we can remove the frozen water by sublimation, avoiding the liquid phase, and reducing the distortion. This rate of sublimation is very much a function of temperature and vacuum, and associated drying time which is in the order of several hours or longer. Ideally, freeze drying could be carried out at temperatures below the recrystallization of ice, which will require an inordinately long drying period. In practice, temperatures of -60°C have been found to give reasonable results under vacuums achievable with two stage rotary pumps, having ensured that good, fast freezing of the specimen has been carried out initially.

Peltier cooled stage The EMS 750 Freeze Drier operates at rotary pump vacuum using a 'Peltier' Thermoelectric stage, with drying temperatures of the order of -60°C, with back-up water cooling at a nominal 15°C. Both the Temperature and the Timer can be pre-selected, and the drying cycle will be completed automatically. Provision is made at the end of the drying cycle to allow the specimen to assume room temperature, or be subsequently warmed prior to embedding. Disposable desiccant containers are located in the preparation chamber to enhance the water vapor removal, and with a suitable container, the vacuum chamber can be utilized to prepare liquid nitrogen 'slush' for fast freezing.

Features

Thermoelectric cooling and heating
Convenient to use cold stage
Accurate temperature and time monitoring and control
Automatic drying cycle
Modular electronics
Clean line design
Polycarbonate safety shield

Specifications

Instrument Case	450mm(W)x350mm(D)x175mm(H)
Work Chamber	Borosilicate Glass: (H) 165mm(Dia.)x125mm
Weight	18Kg
Specimen Stage	-60°C to +60°C
Vacuum Gauge	ATM to 1 x 10-2 mbar
Temperature Controller & Monitor	-90°C to +90°C Display Resolution to 0.1°C
Timer	0-999 Hours
Supply	115 volts 60 Hz (12 amp Max incl pump) 230 volts 50Hz (6 amp Max incl pump)
Services	Water Cooling at nominal 15°C
Vacuum Pump (Recommended)	Complete with vacuum hose and oil mist filter 85L/Min
Size	470mm(L)x150mm(W)x250mm(H)
Weight	20Kg

Ordering Information

91080	EMS 750 Freeze Drier complete with accessories	POR	Request Quote
91005	Rotary Vacuum Pump	$2,306.00	Add to Cart

Replacement Parts

91013	Glass cylinder 165mm (6")		$175.00	Add to Cart
91014	"L" Gasket to suit 165mm ( 6") cylinder)	1 pair	$95.00	Add to Cart
91085	Desiccant Containers (set of 3)		$10.00	Add to Cart
91086	Slushing pot

Optional Accessories

91040	EMS 250 Carbon Coating Attachment	POR	Request Quote
91082	EMS 350 Sputtering Attachment	POR	Request Quote

For more information on Freeze Drying, please see Freeze Drying Principles.

EMS 775 Turbo Freeze Drier

FREEZE DRYING:

The application of freeze drying for specimen preparation for TEM and SEM is a well established practice.

Its application is to reduce the distortion which occurs when a wet specimen dries by normal evaporation. This distortion is due to the forces of surface tension going from a liquid to a vapor phase such as water to water vapor, commonly the situation in a Biological Specimen. However, if we freeze the specimen and maintain it frozen, then by applying a vacuum, we can obtain a situation where we can remove the frozen water by sublimation, avoiding the liquid phase, and reducing the distortion. This rate of sublimation is very much a function of temperature and vacuum, and associated drying time which is on the order of several hours or longer. Ideally freeze drying could be carried out at temperatures below the recrystallization of ice, which will require an inordinately long drying period. In practice, temperatures of -60°C have been found to give reasonable results under vacuums achievable with two stage rotary pumps, having ensured that good, fast freezing of the specimen has been carried out initially.

EMS 775 Turbo Freeze Drier For particular applications, however, it can be necessary to freeze dry at temperatures below -80°C with lower sublimation rates for delicate specimens. This requires a better vacuum than can be obtained using a rotary vacuum pump.

The EMS 775 Turbo Freeze Drier operates at temperatures down to -140°C and employs a Turbomolecular pumping unit, backed by a Rotary Vacuum pump.

The lower temperatures are achieved by using a Liquid Nitrogen fed Cold Stage.

The pre-frozen specimens are admitted into the cooled stage of the drying chamber through a vacuum gate valve which interfaces to the specimen transfer chamber.

The system incorporates both Time and Temperature Control, and at the end of the drying period, the stage may be heated prior to specimen removal. The system also has facilities for purging with Nitrogen Gas.

For extended drying periods, an auto top-up device can be provided as an option to continuously 'fill' the chamber's liquid nitrogen dewar.

The option of a custom designed specimen freezing chamber to produce 'slushy' sub cooled liquid nitrogen is available which also interfaces to the specimen transfer chamber.

The option for a carbon coating attachment to carbon coat without breaking a vacuum is available.