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9112A Calibration Furnace
User's Guide
4.3
4.4
4.5
4.6
14
"Dry-out" Period
WARNING: Before initial use, after transport, and any time the instru-
ment has not been energized for more than 10 days, the instrument needs
to be energized for a "dry-out" period of 1-2 hours before it can be as-
sumed to meet all of the safety requirements of the IEC 1010-1. If the
product is wet or has been in a wet environment, take necessary measures
to remove moisture prior to applying power such as storage in a low hu-
midity temperature chamber operating at 50°C for 4 hours or more.
Power
The furnace utilizes a grounded AC supply of 230 VAC (±10%), 20 amps, sin-
gle phase, 50/60 HZ. An eight foot 2 conductor with ground, power cord is pro-
vided. A separate ground connection is provided and required to permanently
connect the instrument to earth ground for added operator safety.
WARNING: Ensure accessability to the mains plug for disconnection
from supply source.
Equilibration Block Assembly Installation
After the furnace has been installed and the permanent earth ground appropri-
ately attached, the equilibration block assembly may be inserted. Carefully in-
sert the block assembly into the tube with its insulation packing per Figure 1.
Extreme care should be taken installing the Equilibration Block since it is very
heavy and the fused silica tube is very fragile. A 1/8 to ¼ inch air gap between
the front access plate and the front panel of the furnace is required in order to
prevent the front panel from getting too hot. Care must be taken to prevent dirt,
insulation, or anything else from getting between the block and the fused silica
tube or it might break during heat up due to thermal expansion differences. The
fit between the block and the tube is typically loose in order to accommodate
this expansion.
CAUTION: If the furnace must be moved for any reason, remove the
block assembly to prevent breakage of the fused silica tube.
Probe Installation
Install the temperature control and over temperature cutout probes from the as
shown in Figure 1 and Figure 3. Insert the probes carefully to the depth shown
in order to insure that the sensor is properly located in the equilibration block.
The control probe should be inserted through the guard cover first so that the
cover can be properly installed afterward. Position the rear guard block as
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