Shellab SCO2W-2 - Manual (Page 13)

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displays the CO
2
concentration directly on the digital display, reads the CO
2
set point and
controls the percentage of CO
2
in the incubator chamber.
F. The IR controlled unit is known as a direct sensor and operates under the principal that a
certain frequency of infrared light is absorbed by CO
2
. The more CO
2
is present the more
light is absorbed. Its accuracy is consistent no matter what the conditions are in the
incubator. The IR controller utilizes an infared spectrophotometer to directly read the flow of
CO2 gas into the chamber.
G. It is recommended that the accuracy of your CO
2
control system be monitored by measuring
the actual CO
2
concentration on a weekly basis with a Fyrite or other measuring device.
This should be done when the chamber has not been disturbed for an extended period of
time, i.e. after the weekend, or first thing on Monday morning.
5.10 Setting the CO
2
Control: Attach the supply hose to the incubator and turn on the CO
2
supply. Set
the CO
2
control to the desired set point using the procedure described in section 5.3.
5.11 Adjusting CO
2
Display: After the incubator has had several hours to stabilize at CO
2
set point,
measure the actual CO
2
% with a Fyrite. If there is any difference between the Fryite and the display,
use the procedure described in section 5.4 for making the display match the Fyrite. See Section 7.0
for Fyrite use.
NOTE: When using the Fyrite, insure that gas is not being injected while the reading is being
taken. Changing the CO
2
set point to 0.0 prior to taking the sample and change the set point
back to the desired value after the use of the Fyrite is finished.
5.12 Audible Alarms: The temperature control and the CO
2
control are both equipped with visual and
audible alarms.
A. Temperature Alarms: The temperature control has alarm indicators for high and low
conditions that are activated whenever the actual temperature is 1

above or below the set
point.
B. CO
2
Alarms: The CO
2
controller has alarm indicators for high and low alarm conditions that
are activated whenever the actual CO
2
% is 1% above or below the set point.
C. Audible Alarms: Both controls are equipped with audible alarms that are activated when
either of the HIGH or LOW indicators are activated. The audible alarms can be muted for a
single alarm occurrence by pressing and holding down either the UP or DOWN button for
several seconds until the alarm mutes. There is a built in delay of approximately 15 minutes
on the occurrence of a LOW alarm. This time delay prevents the audible alarm from
activating every time the door is opened and the temperature and CO2 drops.
5.13 Description of nGS (NO Gas Warning) Function: (If equipped)
The CO2 Low alarm activates 15 minutes after the CO2 level drops more than 1% below the set
point. If the cause is not corrected in the next 5 minutes the CO2 display will flash nGS, indicating
a no gas warning. nGS will continue to flash until the CO2 level is within 1% of set point (or above
4% if the set point is 5%). The audible alarm can be muted but the visual low alarm indicator will
continue to be lit and the display will continue to flash nGS until the low alarm deactivates. No
action is required by the user other than to correct the cause of the CO2 drop. Note: It may take
several hours after loss of gas before the CO2 low alarm comes on. This depends on the
unit’s
natural rate of decay if no CO2 is injected. CO2 low alarm does not activate until CO2 has fallen
more than 1% of set point (or below 4% if set point is 5%).
Restore gas supply. Check CO2 tank and gas supply lines to the unit.
As soon as the gas supply is restored and the CO2 level rises to less than 1% below set point
(above 4.0% if set point is 5%) the display will stop blinking nGS and will again show the sensor
reading. No action is required by the user other than correcting the cause of the drop in gas
supply. The audible alarm can be muted but the visual low alarm indicator will continue to be lit
and the display will continue to flash nGS until the low alarm deactivates.