Martin-christ Epsilon 2-10D LSCplus Instrukcja Użytkownika Pobierz pdf (Strona 18)

Freeze-dryer EPSILON 2-10D LSCplus

2 Layout and mode of operation

Version 04/2013, Rev. 1.5 of 16/12/2014 • sb

Translation of the original operating manual

Fig. 10: Vapour pressure curve above ice

From a physical point of view, the freeze-drying process covers three

phases (see figure below):

(1) Freezing: The product to be dried is frozen under atmospheric pressure.

This can be done either directly in the freeze-dryer or in a separate deep-

freeze. The freezing temperature should be approximately 10°C below the

solidification point of the product.

(2) Evacuation: When the product is sufficiently frozen, the vacuum pump is

activated. The pressure inside the drying chamber will be lowered to the

value that corresponds to the freezing temperature in accordance with the

vapour pressure curve above ice.

(3) Sublimation: Thermal energy is added to the product, thus starting the

sublimation process. Due to the added energy, the water in the product is

converted into water vapour. Since the ice condenser is much colder than

the product that is to be dried, the vapour pressure in the ice condenser is

considerably lower than above the product. As a result, the water vapour

that is released by the product streams to the ice condenser, where it

condenses on the condenser coils.

Once the free water has been extracted from the product during the main

drying phase, the last traces of bound water will also be removed at a final

pressure that is as low as possible and at higher temperatures. This takes

place by way of  desorption. This drying phase is also called final drying.

6.11 mbar

0.37 mbar

-30°C

Melting

Sublimation

Triple point

SOLID

LIQUID

GASEOUS

Pressure

(mbar)

Temperature (°C)

1 2 ... 13 14 15 16 17 18 19 20 21 22 23 ... 134 135

Brak uwag

Martin-christ Epsilon 2-10D LSCplus Instrukcja Użytkownika Strona 18