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.
1From IdLE , press OPTIONS repeatedly until TCOS appears.
2Press ENTER. C O , or a Thermocouple Offset, will appear.
3Using 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 | H | Kiln will fire hotter | |
C | C | 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
1From IdLE , press OPTIONS repeatedly until TCOS appears.
2Press ENTER. TC1¯ (top thermocouple) will appear.
3While 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 |
| ||
4When the correct thermocouple appears, press
ENTER.
3Using 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:
1From IdLE , press OPTIONSrepeatedly until CHG- appears.
2 Press ENTER. Use the 1and 2keys to select °F or °C .
3After 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
CAUTION: Be careful about changing the thermocouple type! If you select
1From IdLE , press OPTIONS repeatedly until TC appears.
2 Press ENTER. Use the 1 and 2 keys to select TC K TC R or TC S .
3After selecting one of the above, press ENTER. Press STOP to return to IdLE .
19
