Sentry Industries Sentry Xpress 4.0 - Manual (Page 5)

5
Rate
Each segment must include a rate, which is degrees of
temperature change per hour.
The kiln will fire at full power when the rate is
1799°F/999°C. Full power displays as .
Note: To enter full power from , press the
key once.
Hold
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 maintains a steady temperature for the
length of time you specify. You can use Hold in both heat-
ing-up and cooling-down segments.
When Hold is set to 99.59 hours, the controller will re-
main at that temperature indefinitely, until you press
. To enter a 99.59 hour Hold, press the
once from 00.00 during programming.
Note: During a Hold, the display flashes between the
Hold temperature and time left in Hold.
Two Firing Modes:
Single-Speed and Ramp-Hold
To give you greater flexibility, your controller has two
firing modes:
Single-Speed Mode (see next page)
Often times, all you will need is Single-Speed mode,
which has one segment that includes a rate (temperature
change per hour), a target temperature, and (if needed)
hold time.
In Single-Speed mode, you can choose one of five firing
speeds. Then enter the temperature you are firing to.
Ramp-Hold Mode (see page 7)
Ramp-Hold mode offers much greater flexibility than
Single-Speed mode. Use Ramp-Hold to create custom fir-
ings with up to 8 segments. The controller can store 4
Theory of
Operation
The temperature you are firing to is called the target
temperature. After the controller reaches the target tem-
perature, it can also hold that temperature.
The controller fires at a controlled heating rate. The rate
is figured in degrees per hour. If you selected a rate of 100°
per hour, it would take 10 hours for the kiln to reach 1000°.
Rate is similar to “miles per hour.”
In summary, the controller does three basic tasks:
1) It fires at a controlled heating rate, or speed, mea-
sured in degrees of temperature change per hour.
2) It fires to a target temperature.
3) It can hold the target temperature.
The controller fires in segments, or stages. A segment is
a given heating rate to a targettemperature.Shown above is
a segment with a rate of 625° per hour, a target temperature
of 1250°, and a hold of one hour.
Heating rate is figured in degrees per hour. The recom-
mended heating rate for the material you are firing is usu-
ally available from your supplier. It also varies depending
on the thickness of the material.
To figure how long a firing segment will take, subtract
the current temperature from the target temperature and
divide the resultant temperature by the heating rate. In the
diagram above, the firing time is 1250° - 80° (room tempera-
ture) = 1170 ÷625 = 1.87 hours.
The controller can fire up to 8 segments per firing. One
segment is often all that is needed, though.
After the controller has finished firing the last segment,
it will turn off power to the elements.
Note: If you enter a rate of 0000 in segment 1, or if the
target temperature in segment 1 is lower than the cur-
rent temperature, will appear in the display.