INNOV@ ECFAN DHR -AGU-0912-E
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Evacuation and Charging Operations
4.1
Introductions
The contemporaneous presence of liquid and vapour requires for both to be in a state of saturation (Gibb’s law),
as shown in Fig. 8. In thermal equilibrated conditions, the pressure in the tank corresponds to the ambient
temperature. Withdrawal of refrigerant from the tank has following effects:
·
... withdrawal of refrigerant charge:
.... ....
pressure drop inside the tank.
·
... pressure drop inside the tank:
.. ..... ....
T drop & change of status.
·
... T drop & change of status:
.. .... ..... ....
evaporation of part of the liquid, causing a cooling down of the liquid.
·
... cooling of liquid:
.. .......... .... .... ..... ....
thermal exchange with ambient air, further evaporation of remaining
iquid;the original pressure in the tank will be restored after a certain
period of time.
Fig. 8
Gibb’s law diagram
4.2
Full vacuum and charge of the unit
Vacuum cycle
In general it is better to apply a “long” rather than a “hard” vacuum: reaching a low pressure too abruptly may in
fact cause that any remaining humidity evaporates instantaneously, thus freezing part of it.
Fig. 9
Vacuum cycle diagram
This type of work must be carried out by qualified personnel only trained to do their job in
accordance with current laws and regulations.
P
Enthalpy h
T tank/ambient
Saturated gas
Saturated
liquid
P [Pa]
Time
200 s
6
150
Summary of Contents for INNOV DM R Series
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