Factory Installed Options; Back Up System (Bus); Install Vent Stack, Solenoid And Injection Assembly - Thermo Scientific 902 Operating And Maintenance Manual

Back Up System (BUS)

- P/N 1960445, 1960447
Install Vent Stack, Solenoid
and Injection Assembly
Thermo Scientific

Factory Installed Options

Section 5
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.
The built-in BUS (back up system) maintains 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. Install the injection assembly through the 1/2" pre-punched hole,
directly behind the 2" vent stack hole in the center of the chamber
ceiling.
Note Cover the open end of injection assembly with tape to keep
insulation from entering the nipple.
2. Slide 3/8" flatwasher over open end of nipple.
3. Insert the covered end of the injection assembly through the exterior
hole.
4. Remove the tape covering from the end of the nipple and install the
1/8" NPT brass tee on the open end of the nipple. Place Permagum
sealant between the brass tee and the interior top.
5. Remove the two Phillips head screws securing the metal bracket on the
vent stack assembly.
6. Install the vent stack through the opening and secure it to the top of
the freezer, using screws.
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Model 900 and 5900 Series 5-1