Dräger caleo - Humidity Control

Theory of Operation
159
Operating Instructions Caleo, Software 2.n
Humidity Control
Humidity Control
*
Caleo provides a means for hygienic humidification of the
incubator air
*
by evaporating (boiling) water from a separate
supply (water bag or water reservoir).
With closed-loop humidity control, only the desired relative
humidity setpoint is entered, and Caleo then automatically
controls the evaporator output of the humidifier to maintain the
preset relative humidity in the patient capsule.
Caleo allows to control humidity in two different fashions:
– manual adjustment of humidity setpoints,
or
– automatic humidity control (AUTO humidity).
Manual humidity setpoints
A value between 30 % and 99 % relative humidity can be set.
The actual humidity level is measured by a humidity sensor in
the patient capsule (integrated into the sensor module at the
head end of the patient capsule). If the setpoint is higher than
the actual measured relative humidity (air too dry), the
humidifier receives a signal to allow more water vapor into the
patient capsule. Relative humidity inside Caleo therefore rises.
If the set value is lower than the actual measured relative
humidity (air too humid), the humidifier receives a signal to
allow less water vapor into the patient capsule.
Relative humidity inside Caleo therefore falls.
AUTO humidity
In closed-loop humidity control, the user can choose between
setting relative humidity setpoints manually (see above) and
AUTO setting. In AUTO mode, the setpoint for the relative
humidity is calculated and set automatically by the system as a
function of air temperature (see graph to the right).
This function is based on the observation that small and
relatively immature infants require both a higher air
temperature and higher relative humidity than larger infants.
Consequently, in AUTO mode, the set value for relative
humidity is calculated and set as a function of air temperature.
The lower the air temperature setting, the lower the set value
for relative humidity.
* Available option
105
Automatic closed-loop humidity control
Set value for air temperature [°C]
Set value for relative humidity [% r.h.]
100
90
80
70
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30
20
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10
0