Shellab BACTRON600 - Manual (Page 25)

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OPERATION (CONTINUED)
Accessing the Workstation
Items such as media containers and laboratory equipment can be introduced to or removed from
the
BACTRON’s anaerobic environment through the pass box. The pass box creates a near
anaerobic environment through three cyclic applications of the BACTRON’s vacuum pump to
reduce air volume in the pass box, followed by gas replenishment injections. The pass box
operates in one of two modes: A user-initiated three stage auto-cycle, or through use of the manual
control switch to cycle the pass box atmosphere three times. The option to manually cycle the pass
box is primarily intended as a backup for the auto cycle system.
Users can access and work glove-free in the workspace chamber by donning the sleeve
assemblies attached to the front panel arm ports. The sleeve assemblies are also compatible with
exam gloves for handling pathogenic samples inside the workspace. After being donned
– but prior
to opening the arm port doors – the sleeve assemblies are purged by using the foot pedal assembly
to apply reduced pressure to the sleeves with the vacuum pump, then to charge the sleeves with
AMG.
Purging, sealing, and effective use of the sleeve assemblies requires bare skin contact between the
widest part of the user’s forearms and the cuff ring of the sleeve assembly. Smooth, small items
held in hand may be introduced into the workspace chamber through the sleeve assemblies.
Incubators
BACTRON300 and BACTRON900 are each provided with a cabinet style incubator in the
workspace chamber. The BACTRON600 and BACTRON900 come with a rotating tray (Lazy
Susan) in a side storage incubator.
Each incubator ’s temperature is controlled b y a digital controller board using a solid state
temperature sensor probe attached to the incubator body and a heating element. When heating the
incubator, the controller uses Proportional
– Integral – Derivative (PID) analytic functions to slow
the rate of heating as it approaches the user-selected set point. This is done to avoid overshooting,
and to correct for naturally occurring measurement errors.
The digital controller also uses PID learning functions to optimize its warming rates for hotter or
cooler environments. If the BACTRON is moved to a new location with a significant temperature
difference from its previous surroundings, it may require 24 hours of incubator run time for the
controller to fully adapt to the new thermal environment and obtain its previous high level of
temperature stability. This is why the incubator should be run at its application set point for 24 hours
prior to calibration. Additionally, the heat loss from leaving the incubator doors open for long
periods of time (an hour or more) can trick the controller into thinking it is operating in a cool
environment. This can result in a period of temperature overshooting.