E3000

The design of the E3000 features a horizontal pressure chamber measuring 30.1mm internal diameter x 82mm in length. The chamber has an external water jacket for temperature control and specimens are introduced via a removable rear door. The front of the chamber is fitted with a 25mm diameter window which permits easy viewing of the liquid level.

E3100

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.

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 E3000 and 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

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.

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.

Both the E3000 and E3100 are supplied with a standard tissue holder (boat). The E3000 comes with the E3000-01 tissue boat and has a single slot with three tissue baskets. Specimens are loaded into each basket and the gauze lid moved laterally to seal the top.

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, with photographs of these shown above.

Bonded chamber seals – Nitrile or EPDM?

All models of E3000 and E3100 are 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 E3000 or 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 spares items.