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Customizing Chamber Transitions

Do you know how your plant growth chamber controls changes for variables like temperature, relative humidity, light intensity and C0₂?

CMP6060 controller installed on walk-in growth chambers

Generally, there are two ways to control chamber conditions like temperature, relative humidity, light intensity and C0₂ - in a step-like fashion or as a gradual change to new set points. The optimal method depends on your overall research objectives, methodology and the capability of your chamber’s control system to accommodate either or both of these transition styles.

Step Transitions: When conditions in a controlled environment like temperature, RH, light and C0₂, are set to change in a step-like fashion, the new set point will activate the chamber’s mechanical process to adapt  to the new set point value as quickly as the physical system is capable. For example, when a program holding steady at 15°C encounters a new set point of 25°C, the chamber will cease cooling until it reaches 25°C. The actual temperature, however, will not match the set point instantaneously; rather, it will take time for the conditions in the chamber to reach the desired set point. The ability to achieve set point targets will depend on system loads and capacities. As depicted in the graph below, there will also be some degree of variation between the set point and the actual condition while the chamber adjusts to the new target.

Gradual Transitions: When chamber conditions are set to change gradually to a new set point, a smooth linear transition occurs. This may be desirable in experiments where the researcher’s objective is to more closely mimic transitions that occur in the natural environment. In this case, the chamber provides  significantly less variation between the set point and the actual condition during the transition. See graph below.

Conviron offers control systems that allow for different transition methods (step vs. gradual) and rates - as well as enabling simultaneous transitions of multiple chamber conditions. For example, rapid changes in temperature may be combined with very slow changes in light intensity, humidity or C0₂.

 

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