Operating instructions

The cone bent too far: Use a
negative Cone Offset for a cooler
firing, such as -10 (°F).
Note: Do not be overly con
-
cerned with achieving an exact 6
o’clock bend. The difference be
-
tween a 3 o’clock and a 6 o’clock bend is only a few
degrees.
When Cone Temperature
Is Off More Than 20°F/11°C
The maximum amount that Cone Offset can change the
temperature is 20°F/11°C. When the temperature is off
more than that amount,correct with Thermocouple Offset.
FAN
Control the Optional AOP Receptacle in Cone-Fire
The AOP (auxiliary output) is a special-order kilnswitch
box receptacle. The Sentry controls the power to the AOP
receptacle. The AOP is usually used to power a kiln vent. In
the Fan option, select when an AOP-powered kiln vent will
turn on during Cone-Fire.
Beforethe Fan optionwill appear on theOptions list,(1)
you must enter a Cone-Fire program in active memory and
(2) you must select in the AOP1 or AOP2 option.
(See page 22 for instructions on selecting .)
From , press repeatedly until
appears.
Press . Use the and keys to se-
lect one of these settings:
I
The vent is on during Pre-Heat, the
cone firing, and Slow Cooling. It turns off
at 212°F/100°C.
I
The vent is on during Pre-Heat and
the cone firing. Then it shuts off. (It is off
during Slow Cooling.)
I
The vent is off all the time.
After selecting one of the above, press
. Press to return to .
Note: If thetemperature is above 1650°F / 900°C and
the kiln is struggling to reach temperature, the vent fan
will automatically turn off.
General Options
General options are available on all Sentry controllers.
TCOS / Thermocouple Offset
Calibrate the Thermocouple(s)
The thermocouple is the rod protruding into the firing
chamber. It measures temperature. Thermocouples can
“drift” as they age, causing a shift in temperature readings.
Thermocouple Offset calibrates the controller to compen
-
sate for drift.
Note: The thermocouple must protrude into the firing
chamber the correct distance: 1” for ¼”wide
thermocouples,
1
2
" -
5
8
" for 1/8” wide thermocouples.
Thermocouple Offset for Ceramic Firings
In ceramics, Cone Offset (see page 20) adjusts only one
range of pyrometric cones without affecting the other
cones. Thermocouple Offset, on the other hand, affects all
cones and all Ramp-Hold firings equally. For example, a 5°
hotter setting in Thermocouple Offset fires everything 5°
hotter.
Note: If you find that all your cones are consistently
under- or over-firing, adjust Thermocouple Offset. If
you need to adjust only a particular cone, use Cone
Offset.
Calibrating Thermocouple Offset
With a Digital Pyrometer
You can calibrate Thermocouple Offset using a cali
-
brated digital pyrometer. Oneway to calibrateyour pyrom
-
eter is to take it to a heat treater or other location that has a
calibrated controller you can trust. Take a reading from a
furnace with your pyrometer. Either zero it out to match
the calibrated controller on the furnace, or write down the
temperature difference between your pyrometer and the
reliable source. Store your pyrometer. Use it only for cali-
brating controllers. Thus, it remains a reliable calibration
standard.
Note: The temperature at which you calibrated your
digital pyrometer should be the same temper-
ature you use to check the controller’s tem-
perature readout. Example: If you took a
reading from a reliable source at 2000°F, you
should check the controller reading at
around 2000°F.
Mount the thermocouple of the calibrated
pyrometerin thefiring chambernear the Sen
-
try’s thermocouple. With the Sentry on Hold,
compare readings between the Sentry and the
calibrated pyrometer. Adjust Thermocouple
Offset to compensate for any temperature
difference between them.
Note: You can also return your controller to the fac
-
tory to have it calibrated on certified test equipment.
Setting Thermocouple Offset
You can enter a temperature change up to 45°F/25°C
higher or lower than the zero factory setting.
From ,press repeatedly until
appears.
Press . , or a Thermocouple Offset, will
appear.
Using the and keys, enter the new offset. (See
chart on next page.) Press . will ap
-
pear. To return to , press .
21
Cone Offset af-
fects a range of
cones in
Cone-Fire mode.
Thermocouple
Offset affects all
firings in both
modes.