Shel lab BACTRON300, Installation And Operation Manual, Page: 35 / 86

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OPERATION (CONTINUED)
The Over Temperature Limit System
The OTL is a mechanical heating cutoff included with each incubator, and which operates
independently of the incubator microprocessor. It is intended to be set by the user to approximately
1
°
C above the current operating temperature set point. The OTL prevents runaway heating in the
event that the main controller fails while in its heating mode.
If the incubators temperature exceeds the OTL cutoff setting, a red indicator illuminates and an
alarm buzz sounds. At the same time OTL depowers the incubator heating elements. It will
continue to do so as long as the incubator air temperature remains higher than the OTL cutoff
setting.
Manometer Pressure Gauge and Check Valve
The water-filled manometer in the workspace chamber serves as a visual pressure gauge and
dynamic venting check valve during instances of excess overpressures. The manometer is filled to
the top reference ring when the chamber is at room pressure. When an anaerobic atmosphere has
been established and the chamber is under overpressure, the water will be forced down by 0.5
inches to the bottom reference ring.
Figure 25: Chamber Manometer8
An increase in atmospheric pressure inside the workstation drives down water farther within the
Manometer. Excessive pressure will cause the water to bubble as chamber atmosphere is vented
through the manometer and out of the workstation. This helps prevents damage to workstation
gaskets and the acrylic glass panels. The manometer exhaust vent is a port consisting of a
transparent tube and black O-ring located on the back, right side of the BACTRON.