11
set point, the High Limit needs to be adjusted. Previously turned to its maximum
position as stated in section 5.1, now turn the control knob counterclockwise just
until the SAFETY ACTIVATED indicator light comes on. Next, turn the control
knob clockwise just until the indicator light goes off. Then turn the control knob
clockwise two (2) of the smallest divisions on its scale past the point where the
indicator light went off. This should adjust the High Limit set point to
approximately 1
°
C above the Main Temperature Control set point. It is
recommended that the High Limit set point be checked periodically to assure no
changes have occurred. A mark on the dial will aid for future reference if changes
to this set point occur.
5.5
Temperature Alarms:
The Main Temperature Control has visual/audible alarm
indicators for HIGH and LOW conditions that are activated whenever the actual
temperature is 1
°
C above or below the set point. There is a built in delay of fifteen
(15) minutes on the occurrence of the audible LOW alarm. This prevents the
alarm from activating every time the door is opened and the temperature drops.
5.6
Muting Audible Alarm:
The audible alarm can be muted for a single alarm
occurrence by pressing and holding down either the UP or DOWN arrow pad for
several seconds until the alarm is muted and the MUTE indicator comes on. This
means the alarm is muted for that particular condition while it exists, but is not
muted indefinitely or for a separate condition that may occur.
5.7
CO
2
Supply:
As stated at the beginning of this section, do not connect the CO
2
supply to the incubator until the temperatures have been set. Use only MEDICAL
GRADE CO
2
with an in-line filter (provided with your tubing kit) from the tank to the
incubator. These incubators use CO
2
in small quantities. Precise metering of
input is vital for maximum performance and only a two-stage CO
2
pressure
regulator is recommended. Note that some single-stage CO
2
pressure regulators
have two (2) gauges, be certain you are using only a two-stage regulator.
5.8
CO
2
Regulator:
The high-pressure stage of the regulator coming direct from the
supply tank must have a range from 0 to at least 2000 PSI (actual tank pressure
as read on the gauge). The low-pressure stage should have a range from 0 to at
least 40 PSI. The low-pressure gauge indicates actual CO
2
pressure into the
incubator. Connect the CO
2
supply from the low-pressure stage of the regulator to
the 3/8" inlet fitting on the left side of the unit marked CO
2
TO CHAMBER.
CAUTION:
CO
2
pressure to the incubator inlet is rated from 5 to 40 PSI. DO NOT exceed
40 PSI.
5.9
CO
2
Principle of Operation:
The microprocessor CO
2
control system interprets
the information from the CO
2
sensor, displays the CO
2
concentration directly on
the digital display, reads the set point and controls the percentage of CO
2
in the
incubator chamber. The infrared (IR) sensor operates under the principle that a
certain frequency of infrared light is absorbed by CO
2
. The more CO
2
present in
the chamber the more light is absorbed. The IR sensor is only sensitive to CO
2
,
so its accuracy is consistent no matter what the conditions are in the incubator.
