800.545.6566
www.riogrande.com
Sentry Express Digital Temperature Controller
4
Sharing your passion for making jewelry.
Products. Service. Know-how.
Power Failures
After a power failure, the controller will con-
tinue firing provided that:
The kiln temperature is above 212°F/100°C when the
power comes back on.
The temperature dropped no more than 180°F/100°C
while the power was off.
Power Failure Messages
PF 1
The power failed during firing, and tempera-
ture dropped more than 180°F/100°C.
PF 2
The power failed during firing, and kiln tem-
perature was below 212°F/100°C when the power came
back on.
CPLT Message: Firing Completed
When the firing has success-
fully completed, the Sentry
Xpress will shut off power to
the elements. Then three mes-
sages will cycle one after the other:
1.
CPLT
(complete)
2. Firing time in hours and minutes
3. The current kiln temperature
Thunder Storms and Power Surges
Unplug the kiln or disconnect the power when the
kiln is not in use, especially during thunder storms and
in areas with frequent power surges. If the kiln is part
way through a firing when a storm begins, it is probably
okay to continue the firing with close supervision. Do
no leave the kiln unattended.
Theory of Operation
The temperature you are firing to is called the target
temperature. After the controller reaches the target
temperature, 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 target temperature. Shown
above is a segment with a rate of 625°, a target tem-
perature of 1250°, and a hold of one hour.
Heating rate is figured in degrees per hour. The rec-
ommended heating rate for the material you are firing
is usually 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 temperature) = 1170 ÷ 625 = 1.87 hours.
The controller can fire up to 8 segments pre firing.
One segment is often all that is needed, though.
After the controller has finished firing the last seg-
ment, it will turn off power to the elements.
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
FULL
.
Note:
To enter full power from
0000
, press the
Down
Arrow
key once.
Parts of a Segment
500°
1500°
2000°
1000°
2
1
3
4
Ramp
Hold
“Ramp” means to
raise or lower the
temperature.
“Hold” means to
maintain a
temperature.
This segment will reach the target temperature of 1250° in 2 hours, then
hold that temperature for 1 hour.
Rate = Firing Speed
500°
1500°
2000°
1000°
2
1
3
4
Ra
te
=
1000
° per hour
Ra
te
= 500
° per hour
Rate
= 333
° per hour
Hours
Rate is fi gured in degrees per hour
