Shellab SRI20-2 - Manual (Page 7)

7
OPERATION
The refrigeration system, heater, and air circulating fan are used in conjunction with the
temperature control circuit to achieve sensitive temperature control. The thermostat sensor
located in the air stream senses any temperature deviation from the control point, and heat is
provided to maintain desired temperature. The circulating fan provides even air distribution
throughout the chamber and assures temperature uniformity.
Regardless if the temperature maintained, the compressor operates continuously. This
constant operation minimizes component failure which are more frequently associated with a
cycle type operation. Note that a factory set Low-Limit Thermostat will shut off the compressor
when temperatures reach 1

C.
5.1 The power supply must match the unit’s requirements listed on the data plate located on
the side of the incubator.
5.2 Plug the service cord into the power supply and turn the Power Switch to the ON
position. Turn the Overtemperature Thermostat to its maximum position, clockwise using
a coin or flat edged tool.
5.3 Place a certified reference thermometer (not supplied) in the center of the chamber. Be
certain the thermostat is not touching any shelving or chamber walls. Taping the
thermometer to a petri dish raises it off the shelf and keeps the scale in view. Placing
the reference thermometer in the chamber at this stage of operation will allow for
calibrating the control with out the loss of processing time.
5.4 Loading Procedure: Adequate spacing should be allowed between items whenever
possible. Proper spacing will allow maximum air circulation, which is necessary for
temperature uniformity.
5.5 Set Main Temperature: Enter desired set point temperature. To enter set point mode
on the control, press either the UP or DOWN arrow pad one time. The digital display will
begin to blink from bright to dim. While blinking, digital display is showing the current set
point, which can be changed by pushing the UP and DOWN arrow pads until the desired
value is reached. If the arrow pads are not touched within five (5) seconds the display
will stop blinking and read the temperature in the chamber. Allow at least 24 hours for
the temperature to stabilize at set point.
5.6 Calibrating Main Temperature Control: It is recommended that calibration is done
once the unit is installed in its working environment and has been stabile at set point for
several hours. Once stabile, compare the reference thermometer with the digital display.
If there is an unacceptable difference, put the display into calibrate mode by pushing
both UP and DOWN arrow pads at the same time until the display blinks on and off.
While blinking, the display can be changed to match the reference thermometer by
pushing the UP or DOWN arrow pads. If no arrow pads are pushed within five (5)
seconds the display will revert to displaying the set point. Allow the incubator
temperature to stabilize again, and repeat the process if necessary.
Section
5