Sentry Industries Sentry 2.0 - Manual (Page 11)

Watch the pyrometric witness cones through the peep-
hole. Press STOPwhen the correct witness cone bends, not-
ing how much Hold time was needed. Program that much
Hold time the next time you fire the same type of ware loaded
to the same capacity.
Note: During Hold, the display temperature will
alternate with time left in Hold. To figure hold time
for the next firing, subtract time left in Hold from
the total Hold time entered.
When Hold is set to 99.99 hours, the Sentry will remain at
that temperature indefinitely, until STOP is pressed.
Slow Cooling (COOL)
Slow cooling enhances the quality of some ceramic
glazes. Slow cooling encourages crystal develoment, deeper
gloss, and sometimes startling color shifts. Iron red glazes
seem to respond well to slow cooling. For these reasons we
have added a Slow Cooling feature to Cone-Fire.
■ Slow Cooling begins after the cone firing (and Hold, if
any) and ends at 392°F/200°C.
■ When COOL appears in Cone-Fire programming, enter
a cooling rate between 1°F/C to 180°F/82°C. A good start-
ing point is a rate of 90°F/50°C.
■ Enter a rate of 0 to turn Slow Cooling off.
Note: Slow Cooling can extend the firing time by
many hours. For instance, if the shutoff tempera-
ture is 1945°F/1063°C, and the cooling rate is
100°F/55°C, the kiln will take 15 ½ hours to reach
392°F/200°C.
When the Kiln Shuts Off Too Soon
If the kiln shuts off before the pyrometric witness cone
bends, you can turn the kiln back on and keep firing. Simply
program the next hotter cone in Cone-Fire. Then from
IdLE , press START. The kiln will begin firing, taking up
where it left off.
Note: By looking at the witness cones through a
peephole, you will know if the kiln shuts off too
soon.
If the kiln shuts off within 100°F/55°C of maturity, and the
temperature drops 50°F/28°C or more after the kiln shuts
off, do not depend on the witness cones. Once they cool
50°F/28°C after they have been heated to within 100°F/55°C
of maturity, they will not bend properly. This is because they
form a hard shell.
Wrong Thermocouple Type
If a Type-K thermocouple is installed on your kiln, but
your controller is set for Type-S, the kiln will continually
underfire by a wide margin. See page 19 to check thermo-
couple type.
For Kilns with AOP Outlet
The AOP (auxiliary output) is a special-order receptacle
mounted in the kiln switch box. The Sentry controls power
to the AOP receptacle. The AOP is usually used to power a
kiln vent.
The Fan option, which is accessed through the OPTIONS
key, determines when an AOP-powered kiln vent will oper-
ate during Cone-Fire.
Before the Fan option will appear on the Options list, (1)
you must enter a Cone-Fire program in active memory and
(2) you must select FAN3 in the AOP option. (See page 20
for instructions on selecting FAN3 in the AOP option.)
1 From IdLE , press OPTIONS repeatedly until FAN
appears.
2 Press ENTER. Use the 1 and 2 keys to select one of
these settings:
■ ON The vent is on during Pre-Heat, the cone firing,
and Slow Cooling. It turns off at 212°F/100°C.
■ OPT The vent is on during Pre-Heat and the cone fir-
ing. It is off during Slow Cooling.
■ OFF The vent is off all the time.
3 After selecting one of the above, press ENTER. Press
STOP to return to IdLE .
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