Rate As Degrees Per Minute; Rate As Time Needed To Reach The Target Temperature; Hold (Hd ); Temperature Overshoot - Sentry Xpress 5.0 Instructions For Use Manual

Sentry Xpress 5 Cone-Fire / Ramp-Hold
If you want the kiln to fire at full speed, enter a rate of
9999. See step 5, inside the red box on the previous page.
Note: In Program Review, a heating rate of 9999 is
displayed as . When a kiln is heated at full
[FULL]
power, it may overshoot the target temperature,
especially in the lower range. To avoid this, add an
extra segment with a slower rate for the last 50 de-
grees of temperature rise.
CAUTION:
The Sentry Xpress includes error
messages to warn you when the kiln is at the wrong
temperature. Firing the kiln at full rate turns off
some of these warnings. See TEDE, Temperature
Deviation, and HTDE, High Temperature Devia-
tion, page 21.
If you are not sure how fast to fire, remember an old fir-
ing adage: When in doubt, slow it down.

Rate as Degrees Per Minute

Rate as degrees of temperature change per minute
works the same as temperature change per hour. Only the
math is different.
A maximum (Full) rate per minute is 29.97°F / 16.65°C.
After you have entered all the segments for your pro-
gram, zero out the remaining available segments. Do that
by entering 0 for the next available ramp rate.
Rate as Time Needed to Reach the
Target Temperature
After selecting [TIME]
program the amount of time that each segment should take
to reach its target temperature. For example, 1 hour and 30
minutes is programmed in Rate as 01.30.
The Time mode in some ways is different and opposite
the standard degrees-per-hour rate explained above:
For a Full rate, or the fastest that the kiln will fire, select
a time rate of 00.00.
After you have entered all of the segments for your pro-
gram, you will need to zero out the remaining available
segments. To do this, select a rate of 99.00 hours.
Question I programmed a FULL rate, yet my kiln
heated at only 550°F per hour.
Answer The controller is limited by the heating ca-
pacity of each kiln. Your kiln heated at 550° per
hour because that is its maximum heating rate.

Hold (HD )

Hold is the length of time that you want the kiln to re-
main at the target temperature. Hold is also called soak or
dwell time. Hold helps even out the temperature through-
out the kiln. Hold can be used in either heating or cooling
segments.
In programming step 7, previous page, enter the hold
time. When hold is set to 99.99 hours, the Sentry Xpress will
14
in the RATE option, page 22,
Do not leave your kiln unattended during operation.
remain at that temperature indefinitely until you press the
Start/Stop key.
Ceramics: Watch the pyrometric witness cones
through a peephole during hold. Press the Start/Stop key
when the correct witness cone bends, noting how much
Hold time was needed. Program that much Hold time the
next time you fire the same type of ware.

Temperature Overshoot

When a kiln is heated too fast, it may overshoot the tar-
get temperature, especially in small kilns at lower tempera-
tures. To avoid this, add an extra segment to slow the firing.
The segment with the slower rate should begin about 40° -
60° below the target temperature of the following segment.
AOP: Turn on a Fan, Light, or Alarm
The AOP (auxiliary output) is an optional receptacle, or
socket, mounted on the kiln. If your kiln has the auxiliary
output receptacle and you want to use it, see the AOP1 op-
tion on page 22. Follow the instructions to activate the
AOP.
Plug a kiln vent, light, or bell into the receptacle, and use
your controller to turn the receptacle on or off for each seg-
ment. (The light or bell act as alarms.)
During programming,
ment (
[FN 1] [FN 2] [FN 3]
arrow keys to select ON or OFF for each segment.
appear only if the auxiliary output has been activated in the
AOP1 option, page 22.

Programming a Cooling Segment

For controlled cooling, program a segment to a lower
target temperature than that of the previous segment.
Example: You fire at a rate of 500°F per hour to 1450°F
in your first segment. Then you want the kiln to cool at a
rate of 100°F per hour down to 700°F. Here is how you
would program the two segments:
Rate
Segment °F/°C
1 500 / 277
2 100 / 55
Segment 1 is the heating segment. Segment 2 is the cool-
ing segment. The controller does not use minus numbers
for cooling. Just enter a lower target temperature than that
of the previous segment. Segment 2 will lower the tempera-
ture to 700°F / 371°C.
Pointer: If you prop the lid or door of the kiln for a
fast cooling, program a fast cooling rate for that
segment. If you lower the temperature quickly by
propping the lid but program a slow cooling rate,
the controller will raise the temperature again.
Example: Some glass artists flash-cool the glass just after
it fuses. They open the door a few inches to remove heat,
then close it again. This takes the glass down rapidly
through the devitrification range. To program a flash-cool,
[FN] will appear for each seg-
etc.). Use the up and down
[FN]
Temp.
°F/°C Hold
1450 / 788 00.00
700 / 371 00.00
will