Shellab SRI21D-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 temperature 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 of the temperature maintained, the refrigeration system operates continuously. This
constant operation minimizes component failures which are more frequently associated with a
cycling type operation. Note that a factory set Low-Limit Thermostat will shut off the compressor
when temperatures reach around 1

C so samples will not freeze.
5.1 Plug incubator into electrical service corresponding to data plate rating located on the side
of the unit. Turn the power switch to the ON position and turn the Overtemperature
Thermostat to its maximum position, clockwise using a coin or flat edged tool.
5.2 Place a certified reference thermometer (not supplied) in the center of the chamber. Be
certain the thermometer 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 a
reference thermometer in the chamber at this stage of operation will allow for calibrating
the control without the loss of processing time.
5.3 Loading Procedure: Adequate spacing should be allowed between items whenever
possible. Proper spacing will allow maximum air circulation, which is necessary for
temperature uniformity.
5.4 Frost Buildup: Excessive frost buildup on the evaporator coil located on the lower rear
wall can affect temperature uniformity. Liquid containers should never be placed in the
chamber without covers. The evaporation of moisture within the chamber will only add
frost and hasten the need for defrosting. Defrosting instructions are available in
Maintenance Section 6.
Section
5