INSTALLATION
If your new probe is to be installed in an existing probe entry, be advised that your warranty requires that the probe should extend no more than 4" (101mm) into the furnace chamber. This is because, at operating temperatures, the sheath can sag enough to cause breakage of the zirconia-sensing element.
NOTE: Your Gold Probe has been thoroughly tested in our controlled atmosphere furnace. Therefore, the sheath shows evidence of thermal discoloration.
For new installations, an entry fitting must be provided at the furnace wall to permit the probe to extend from 2" to 4" (51mm to 101mm) into the furnace chamber. Listed here are several conditions that should be considered when choosing a location for the entry fitting. Most of these conditions allow for some compromise, and represent, at best, recommendations.
ENTRY FITTING LOCATION
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In top third of work zone......
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Close to control thermocouple......
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Distant from radiant tubes......
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Away from carrier gas entry......
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Clear of work baskets......
A variety of fittings have been used to provide the 1" (25.4mm) NPT entry. The simplest is the 1 1/2" (38mm) coupling, as shown in Fig. 4.
The furnace is prepared by drilling a 1 1/2" (38mm) diameter hole through the wall and the insulation. The hole must be at right angles to the wall to avoid interference with probe insertion. The fitting is then welded or screwed to the wall to provide a gas-tight entry.
Your Gold Probe™ has been shipped with an o-ring compression fitting which allows you to adjust the insertion. Manual tightening of the cap is adequate for side mounting. A wrench should be used for vertical mounting to assure probe will not move. When installing in a hot furnace, insert the first four inches directly, then at a rate of 2" (51mm) per minute in order to avoid thermal shock fracture.
WARNING
Zirconia is thermal shock sensitive. Insert into hot furnace no faster than 2" (51mm) per minute (after first 4 inches or 101 millimeters).
If you already have a control system for your carbon sensor, you have been provided with a reference air supply and perhaps a probe conditioning system as well. It is important to emphasize that the reference air be clean and dry. Any combustibles or moisture in the reference air will cause the sensor to read low, resulting in over-carburization. Avoid the use of lubricated plant compressed air. Air connection at the sensor should be silicone rubber tubing to avoid problems related to the high temperatures normally encountered at the sensor connection block. It is recommended that SSi filter P/N 31033 or equivalent be used with the Gold Probe. This will provide 93% efficiency against 0.01 micron particles for the air reference supply and help avoid contamination of the internal airway and electrode.
