Sentry Industries Sentry 2.0 - Manual (Page 19)

Calibrating Thermocouple Offset
With a Digital Pyrometer
You can calibrate Thermocouple Offset using a cali-
brated digital pyrometer. One way to calibrate your pyrome-
ter is to take it to a heat treater or other location that has a cal-
ibrated 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 tem-
perature difference between your pyrometer and the reliable
source. Store your pyrometer. Use it only for calibrating con-
trollers. Thus, it remains a reliable calibration standard.
Note: The temperature at which you calibrated
your digital pyrometer should be the same tempera-
ture you use to check the controller’s temperature
readout. Example: if you took a reading from a reli-
able source at 2000°F, you should check the control-
ler reading at around 2000°F.
Mount the thermocouple of the calibrated pyrometer in
the firing chamber near the Sentry’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.
Setting Thermocouple Offset
You can enter a temperature change up to 45°F/25°C
higher or lower than the zero factory setting.
1 From IdLE , press OPTIONS repeatedly until
TCOS appears.
2 Press ENTER. C O , or a Thermocouple Offset, will
appear.
3 Using the 1 and 2 keys, enter the new offset. (See
chart below.) Press ENTER. TCOS will appear. To
return to IdLE , press STOP.
Thermocouple Offset Settings
°F Setting °C Setting Result
C 0 C 0 No adjustment
H 1-45 H 1-25 Kiln will fire hotter
C 1-45 C 1-25 Kiln will fire cooler
Thermocouple Offset Examples
Setting Result
H 1 Kiln will fire 1° hotter
H 17 Kiln will fire 17° hotter
C 12 Kiln will fire 12° cooler
Multiple Zone Thermocouple Offset
1 From IdLE , press OPTIONS repeatedly until
TCOS appears.
2 Press ENTER. TC1¯ (top thermocouple) will appear.
3 While TC1¯ displays, press OPTIONS. The other
thermocouple(s), then TCOS , will appear with each
press of the OPTIONS key.
3 zone kilns: TC1¯ TC2 - TC3 _ TCOS
2 zone kilns: TC 1¯ TC3 _ TCOS
4 When the correct thermocouple appears, press
ENTER.
3 Using the 1 and 2 keys, enter the new offset. (See
charts at left.) Press ENTER. The thermocouple you
adjusted (i.e. TC ¯ ) will appear. Select another ther-
mocouple, or return to IdLE by pressing STOP.
Selecting °F or °C (CHG-)
The controller operates in your choice of °F or °C temper-
ature. In °C display, a lighted dot appears in the lower right.
In °F, it disappears. To switch from °F to °C or vice versa:
1 From IdLE , press OPTIONSrepeatedly until CHG-
appears.
2 Press ENTER. Use the 1and 2keys to select °F or
°C .
3 After selecting one of the above, press ENTER. Press
STOP to return to IdLE .
°F/°C Temperature Conversion Formula
Below are formulas for converting temperture between
°F and °C. Converting a firing rate requires a different for-
mula than firing temperature:
Firing Temperature
(i.e. “Fire to 1600°F.” 1600°F = 871°C)
(°C x 1.8) +32 = °F
(°F - 32) ÷ 1.8 = °C
Firing Rate and Temperature Change
(i.e. “Fire at 200°F per hour” or “Fire 200°F hotter.” 200°F =
111°C)
°C x 1.8 = °F
°F ÷ 1.8 = °C
Thermocouple Type (TC)
Select Type-K, S or R Thermocouple
The Sentry can be used with Type-K, S or R
thermocouples. If you specialize in firings above
2200°F/1204°C, you should use the Type-S or R. Type-K is
best suited for temperatures below 2200°F/1204°C.
CAUTION: Be careful about changing the
thermocouple type! If you select Type-S or R,
but your kiln is wired with a Type-K, your kiln will
underfire. If you select Type-K and your kiln is
wired with a Type-S or R, your kiln will OVERFIRE.
After using the Reset (RST) option (page 21), make
sure you have the correct thermocouple selected.
Reset changes thermocouple selection to Type-S!
1 From IdLE , press OPTIONSrepeatedly until TC
appears.
2 Press ENTER. Use the 1 and 2 keys to select TC K
TC R or TC S .
3 After selecting one of the above, press ENTER. Press
STOP to return to IdLE .
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