Shellab SRI21FV-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.
The factory PID settings of the control will cycle the compressor on and off at regular, temperature controlled
intervals. This cycling will cause the temperature to fluctuate above and below setpoint and is perfectly normal. This
setting is highly recommended for Drosophila applications; however it can be changed for other applications. 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: The main temperature control has two displays. The upper displays the actual
temperature of the unit and the lower is the set point. To change the set point, push the up or down arrow
until the desired value is reached. Allow at least 24 hours for temperature to stabilize. It is highly
recommended that operators read the included Watlow manual and refer to it for for advanced programming
applications. As mentioned earlier, the PID settings from the factory will cycle the compressor on and off at
regular intervals. This is done to prevent damage to the incubator during Drosophila applications.
5.6 Calibrating Main Temperature Control: As mentioned previous the main control is set up to cycle the
compressor on and off causing the temperature to fluctuate. To calibrate temperature the incubator must run
at a stable temperature. To make the incubator to run at a stable temperature the PID values must be
changed in the Watlow control. Follow the instructions below to change the PID values to make the
incubator to stabilize and calibrate the temperature. Before starting place a reference thermometer on the
middle shelf like it was explained previously.
Section
5