Fisher Scientific I903C, Operation Manual

Page: 38 / 56

Section 6
Factory Installed Options
Note Before installation of BUS components, make sure the power to the
freezer is disconnected, the battery switch is turned off (O) and the freezer
has warmed to ambient temperature.
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The built-in BUS (back up system) will keep the freezer chamber
temperature below the critical level in the event of a power or equipment
failure. If power to the freezer fails, or temperature increases to the back up
alarm set point, the BUS injects liquefied gas into the chamber to keep the
chamber temperature within the specified range.
The BUS operates on an internal 12-volt, rechargeable battery which is
kept charged during normal operation by the integral battery charger.
1. Locate the mounting hole for installing the injection tee assembly. See
Figure 6-1.
Note Cover open end of injection assembly with tape to keep insulation
from entering the nipple.
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2. Slide 3/8” flatwasher over open end of nipple.
3. Insert the covered end of the injection assembly through exterior hole.
Isotemp ULT Chest 6-1 Fisher Scientific
BUS - Back Up System
Install Injection Assembly
Mounting hole for injection tee
Figure 6-1. Mounting location