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8.Work Plan for Carrying out Freeze-
Drying
8.Plan de travail pour realiser une
lyophilisation
To be able to determine the real temperature at the subli-
mation surface, the chamber (10) must be isolated from the
condenser coils (19). When this is done, the pressure in the
chamber reaches the vapor saturation pressure.
/ Close the valve plate (5) for 5 to 10 seconds.
O Write down the temperature value indicated.
Note:
The pressure and temperature values can also be deter-
mined using a line recorder. A special recorder output
socket (35) can be found at the rear of the unit for this
purpose (Fig.6, page 7).
Example:
The sublimation temperature of the product is -15°C; i.e.,
a temperature of -20°C should not be exceeded. This cor-
responds to a maximum chamber pressure of 1 mbar
according to the vapor pressure diagram (Fig. 9).
- This way of determining the temperature can be used
only if sufficient water vapor is being sublimated.
g) Secondary drying
As soon as primary drying has been completed, proceed as
follows:
V Open the valve plate (5) completely to decrease the
flow resistance as far as possible during secondary
drying.
Stop the pressure regulation as follows:
/ Set the pressure at a value < 5 x 10
2
mbar.
Secondary drying has been completed as soon as the follo-
wing conditions have been attained:
- ultimate pressure has been reached
- the final product temperature has been reached (see
Point 7.2.2, page 23).
- No marked rise is pressure is noticed during a pressure
rise measurement over a measuring period of 60 to 120
seconds.
h) Run down of the vacuum pump (16)
After secondary drying has been completed, the vacuum
pump (16) should be left to run down for approximately 30
minutes. During this, the gas ballast valve should be open,
the shutoff valve (32) or pressure regulating valve (33)
should be closed.
This makes it possible to remove any substances which
may have condensed in the pump oil and lengthens the ser-
vice life of the oil. (See the operating manuals for the TRI-
VAC D 4 B/D 8 B pumps and the manual for the pump
oils).
Afin d'etablir exactement la temperature de sublimation
de la surface du produit, il faut isoler la chambre de des-
siccation (10) de la chambre de condensation (2). Alors
s'etablit reellement la tension de vapeur du produit.
A cette fin :
/ la vanne-plateau doit etre fermee pendant 5 a 10 secon-
des et noter la valeur de la temperature obtenue.
Remarque:
Les valeurs de pression et de temperatures peuvent
egalement etre enregistrces. A l'arriere de l'apparcil,
vous trouverez une sortie d'enregistrement (35) fig. 6,
p. 6.
Exemple:
Temperature de sublimation du produit -15°C, c.a.d., on
ne depassera pas la valeur de t° de -20°C; ce qui corre-
spond a une pression maximale dans la chambre de lmbar
(suivant courbe diagramme, fig. 9).
- Cette facon de proceder peut etre realisee tant que Ton
sublime la vapeur d'eau.
g) Post-lyophilisation
En fin de lyophilisation principale:
/ La vanne-plateau completement ouverte afin d'eviter
tout laminage du flux gazeux.
/ Regulation de pression declenchee. Pour cela: etablir la
valeur de consigne a une pression inferieure a 5 x 1O
2
mbar.
La post-lyophilisation est terminee quand la pression fina-
le et la temperature finale du produit sont atteintes et
egalement lorsqu'on n'obtient aucune remontee de pressi-
on en fermant la vanne-plateau pendant 60 a 120 secon-
des.
h) Phase finale de fonctionnement de la pompe a vide
La pompe a vide (16) fonctionne env. 30 minutes apres la
fin de la post-lyophilisation en phase de regeneration;
c.a.d. la vanne d'isolation fermee - le lest d'air de la pom-
pe a vide etant toujours ouvert.
Par cette fonction, les condensats melanges a l'huile de la
pompe a vide peuvent etre elimines et la duree de fonc-
tionnement avec la meme huile prolongee (voir mode
d'emploi TRIVAC D 4 B/D 8 B).
30
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