Operation
23
GA12119_00_A3 - 01/2012 - © Oerlikon Leybold Vacuum
4
Operation
The cold head is switched on and off with the compressor unit.
For operation, the Operating Instructions for the compressor unit are needed:
13000547_002_xxx (COOLPAK 6000 H / 6200 H)
17200020_002_xxx (COOLPAK 2000 / 2200)
Observe the safety information in Section 0.6.3.
Cooldown Time for 2nd Stages
The cooldown time t
0
of the cold head in a vacuum are specified in Section
1.3.
If the thermal load due to radiation is ignored, the cooldown time with
components attached can be estimated as described as follows:
t
0
=cooldown time of cold head without components
=average refrigerating capacity of the cold head
C=heat capacity of the additional components between 300 and 20 K
⌠
300 K
C =
∑
m
i
c
i
(T) dT
i
⌡
20 K
m=mass
c(T)=specific heat
The following values can be inserted for the integral:
⌠
300 K
Material
ci (T) dT
⌡
20 K
———————————————————————
Copper
79 Ws·g
-1
Aluminium
170 Ws·g
-1
Stainless steel
81 Ws·g
-1
The following values apply for
when operating one cold head with the
recommended compressor unit:
COOLPOWER 5/100
10 W ± 10%
COOLPOWER 7/25
12 W ± 10%
Maximum Permissible Cold-Head Temperature
The temperature of the cold head must not exceed 50 °C at the refrigerating
stages. Higher temperatures may damage components inside the cold head.
Q
2
Q
2
t = t
0
+ ——
C
Q
2
CAUTION
