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P a g e
OPERATION
T
HEORY OF
O
PERATION
Shaking Platform
The unit is equipped with an orbital shaking platform providing circular agitation to samples. The
orbital shaking speed is programmed using the Set RPM controls on the front control panel.
Metal counterweights included with the incubator come installed beneath the shaking platform. The
end-user can add or remove weights to accommodate varying sample loads. This stabilizes the
platform during operation, preventing possible damage from excessive vibration. A severely
unbalanced shaking platform may also cause the unit to move across the workspace.
The intensity of the platform agitation is controlled by adjusting the pivot point of the shaker arm and
repositioning the counterweights installed beneath the platform. These adjustments change the
platform orbit to create moderate or heavy agitation.
Shaking Platform Timer
The incubator timer function allows the end-user to program the shaking platform to agitate for a set
amount of time. When the timer reaches zero, the platform ceases shaking.
Heating
When powered, the incubator heats to and maintains a user-selected target setpoint in the incubation
chamber. The incubator senses the chamber air temperature using a solid-state probe mounted on the
chamber interior wall. When the incubator detects that the chamber temperature has dropped below the
target setpoint, it pulses power to the heating elements inside the chamber walls.
The incubator uses Proportional – Integral – Derivative (PID) control to avoid significantly overshooting the
setpoint. This means the rate of heating slows as the chamber temperature approaches the target
temperature. If the chamber temperature is above the setpoint, the incubator uses minimum heating to
control the rate of cooling and avoid dipping below the setpoint.
Additionally, the PID loops optimize heating rates for the temperature environment around the incubator.
If the incubator is operating in a cool room, it will increase the length of heating pulses to compensate.
Likewise, when operating in a warm room the incubator uses shorter pulses. If the ambient temperature
conditions change significantly, there may be minor over or undershoots as the incubator adapts.
SSI incubators rely on natural heat radiation for cooling. These units can achieve a low-end temperature
just above the ambient room temperature plus the internal waste heat of the unit.