Theory of Operation
Chapter 3: Theory of Operation
Isolette® Infant Incubator (Model C2000) Service Manual Page 3 - 31
3
The impeller also provides the internal circulation at a much greater
flow than that of the fresh gas inflow. The total flow of fresh and
circulated air is directed past the airflow sensor and around the heater.
The air enters the infant compartment up through the slots at the front
and rear of the main deck and then passes between the front and rear
inner walls. The air circulates past the sensor module, which contains
the temperature sensing probe that encapsulates the air temperature
control thermistor and a high air temperature alarm thermistor. After
circulating within the infant compartment, the air then re-circulates
down through a slot in the right end of the main deck, and back to the
impeller. When the access panel of the hood is open, the air continues
to flow upward past the opening, creating a warm air curtain to minimize
the drop in air temperature in the incubator. The temperature is
regulated using either the incubator’s air or the infant’s skin temperature
as the controlling parameter; the desired mode is selected by the front
panel keys.
In either mode of operation, the heater output is proportional to the
amount of heat required to maintain the desired temperature.
Air Mode
In Air Mode, the air temperature is maintained from 68 °F to 99 °F
(20 °C to 37 °C) (99 °F to 102 °F (37 °C to 39 °C) in Temperature
Override Mode), as selected by the Air Set Temperature Up and Down
arrow keys on the front panel. A probe located in the sensor module
monitors the incubator’s air temperature and compares it with the air’s
set temperature setting. The probe supplies this information to the
heater control circuitry, which regulates the heater output to maintain
the air temperature setting. The actual air temperature appears on the
Air Temperature display. A second sensor within the air temperature
probe serves as a backup to limit the maximum incubator temperature.
If the high temperature limit activates, the heater shuts off.
In Air Mode, the infant’s temperature is a function of the air temperature
and the infant’s ability to establish and maintain its own temperature. A
small infant, or one with underdeveloped homeostatic control, may not
be able to maintain a stable temperature at the desired level.
In Air Mode, there is a 15-minute setpoint retention. When you first
power the unit on, the air setpoint temperature is 95 °F (35 °C); for
example, if you change the air setpoint temperature to 95.9 °F
(35.5 °C), and a power failure occurs, the air set temperature comes up
to 95.9 °F (35.5 °C) if the unit turns on again before 15 minutes elapse.
To Next Page
Loading...
Need help?
General
