NuAire NU-5710, Operation And Maintenance Manual

Page: 42 / 64

OM0249 Page 42 of 64
Rev 4 June/2020
When unit chamber has stabilized at the operational temperature, CO
2
%, the RH set point has been chosen and with
water in the tank the heater has been powered for at least 60 minutes ensuring it is up to temperature. Allow the
RH system to achieve set point and stabilize there for at least 30 minutes. Then a measurement with an independent
hygrometer probe can be made It is usually inserted into the chamber through the chamber access port located on
the right side of the incubator. The Hygrometer must be up left undisturbed until it indicates that it is up to the
chamber temperature or until the temperature on the hygrometer stops increasing for at least 5 minutes. Take a
reading then move to the Display Offset Calibration described in the next section to adjust the RH value for the
incubator system.
ACCURACY OF CALIBRATION W/ THE HYGROMETER:
The hygrometer used to calibrate the Incubator sensor will have a tolerance that is specified by the manufacturer of
the instrument. The tolerance of accurate hygrometers can be as tight as + 2% others can have tolerances of + 3% or
greater at this humidity level. This means that when 90% is read on the instrument the actual relative humidity
percentage can be at the high or low limit of the hygrometer’s tolerance. If condensation is encountered the value
that the incubator displays can be adjusted accordingly.
9.5.3 Display Offset Calibration:
Pressing the Calibrate button on the Service settings screen produces the
Calibrate the RH offset screen as show to the right. Press the Calibrated
sensor reading value (blue text) to access the key pad screen then, to
input the independently measured value and press the ENT button on the
key pad. This returns you to the “Calibrate RH offset” screen. I might take
a couple of seconds for the new value to appear in this screen. Then,
press the SAVE button to return to the “Service settings screen”. Pressing
the exit button in that screen will return you to the MAIN screen.
NOTES:
1. When you use the Water pan method of calibration remember to set the “Air Inject Time” back to 5 (sec).
Otherwise Condensation is likely to form in the chamber. That Option is accessed through Service
settings/General/Options button.
2. Choose the desired set-point that you want to run the system at in the “Environmental Set Point screen
remembering that it was set to 0 (zero) for the calibration.
9.6 O
2
Calibration – System available on Models NU-5731 and NU-5741
When unit chamber has stabilized at the operational temperature, CO
2
%, and RH%, O
2
system has been powered for at
least 10 minutes ensuring the sensor is up to temperature - take an O
2
measurement with an independent instrument
through the chamber sample port used for taking CO
2
readings. It is located behind the cover under the incubator outer
door and, if necessary, perform the following:
NOTE: If a Fyrite instrument is used,
BE SURE TO READ THE O
2
FYRITE OPERATING AND SAFETY INSTRUCTIONS
FOR PROPER O
2
MEASUREMENTS AND SAFETY CONSIDERATIONS.
Display Offset Calibration:
Press the Calibrate button on the Service settings screen produces the Calibrate the O
2
offset screen. Press the Calibrated
sensor reading value to access the key pad to input the independently measured value then press the ENT button on the
key pad. When you return the Calibrate O
2
offset screen press the save button to return to the System settings screen.
Press the exit button in this screen to go back to the main screen.
10.0 Maintaining Your DHD