Thermo Scientific BF51728, Installation And Operational Manual

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| Maintenance
9-56
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330985H01
1100°C Box Furnace
Chapter 9
a. Organic contaminants may be removed by burning them out. Refer to section
“Initial Furnace Start-Up/Drying-Out Process” to do this.
b. Inorganic contaminants may embed themselves into the ceramic insulating
materials and heating elements. Recommend replacement. Contact Technical
Service for further use or replacement.
Thermocouple Replacement
Refer to Figure 6 “Thermocouple Replacement” as you perform the following procedure:
1. Remove any atmosphere piping connected to the gas inlet tube assembly (item #2 in
Figure 6).
2. Remove the two screws from the gas inlet tube assembly. Pull the gas inlet tube
assembly straight out of the furnace.
3. Remove the screws from rear panel comers. Remove the rear panel (item # 1 in
Figure 6).
4. Note polarity and wire location. Loosen the terminal screws and remove
thermocouple lead wires.
5. Remove thermocouple mounting screws.
6. Slide out head and old thermocouple (item #3 in Figure 6).
7. Replace the thermocouple and connect new wires. Be careful not to bend the
thermocouple wire. Red is always negative.
8. Replace the furnace rear panel.
NOTE For optimal performance, the thermocouple should be replaced once a year. In
some situations a more frequent replacement schedule is warranted. SnSr or Sbr on
the controller display indicates a broken thermocouple.
CAUTION : Failure to pull the gas inlet tube assembly straight out of the furnace will
result in damage to the gas inlet tube assembly or the heating unit.