![background image](http://html1.mh-extra.com/html/omega/871a/871a_user-manual_737648009.webp)
4.1.2
Accuracy Check
1. Prepare a pure-water ice bath (see paragraph 4.2.3, step 5).
2. Connect a thermocouple probe to input 1 of the unit.
3. Immerse the probe into the pure-water ice bath and allow ten
minutes for thermal stabilization.
4. Turn on the instrument and use Tables 4-1 and 4-2 to verify
that the readings on each range are within specification.
TABLE 4-1
MODEL 871A RANGE CHART
TABLE 4-2
MODEL 872A RANGE CHART
4.2
CALIBRATION FOR MODEL 871A
4.2.1
Equipment Needed
1. DC Voltage Calibrator with 1 ±0.01% of setting ± 20
µV accuracy.
2. 100: 1 divider: 1.98 kilohm and 20 ohm wirewound resistors with
0.02% ratio accuracy or better.
3. OMEGA TRC III Ice Point Reference Chamber or distilled water ice
bath.
4. OMEGA type K TRP Reference Probe or make a thermocouple transi-
tion junction (see paragraph 4.2.3).
4.2.2
Environmental Conditions
To meet all specifications, the conditions for calibration should be an
ambient temperature 23º ± 1ºC; relative humidity less than 80%.
Range
Allowable Reading
2000°F
32°
±
2°
200°F
32.0°
±
1.8°
1370°C
0°
±
1°
200°C
0.0°
±
1.0°
Range
Allowable Reading
1400°F
32°
±
2°
200°F
32.0°
±
1.8°
760°C
0°
±
1°
200°C
0.0°
±
1.0°
6
Содержание 871A
Страница 21: ...SCHEMATIC MODEL 871A DIGITAL THERMOMETER 18 ...
Страница 22: ...SCHEMATIC MODEL 872A DIGITAL THERMOMETER 19 ...