Emerson Rosemount5081, Инструкция по эксплуатации, Страница: 55 / 152

7.2 Calibrating ORP sensors
7.2.1 ORP overview
ORP is a function of temperature. The accuracy of a sensor/transmitter loop is about ± 1 °C.
A new sensor does not need to be calibrated often. Only calibrate the loop when:
1. ± 1 °C is not acceptable.
2. Suspected error in temperature measurement
7.2.2 Calibrating temperature with an ORP sensor
1. Place the ORP sensor and a reference thermometer in an insulated container of
water at ambient temperature. Keep the sensor submerged at least 3 in. below the
water level. Stir continuously and wait at least 20 minutes for the water, sensor, and
thermometer to reach a constant temperature.
2. Press CAL on the IRC to enter the CALIBRATE menu.
The STD submenu appears.
3. At the STD submenu, press NEXT .
The TEMP ADJ submenu appears.
4. Press ENTER to display the temperature editing prompt.
5. Compare the temperature displayed by the transmitter with the temperature
measured by the reference thermometer. If there is a discrepancy between the two
values, use the editing keys to change the measured value to that of the
thermometer.
NOTICE
The reading cannot be changed more than 15 °C.
6. Press ENTER .
The value is saved, and the display returns to the TEMP ADJ submenu.
7. Press EXIT to leave the CALIBRATE menu.
8. Check for linearity by measuring the temperature of water: -10 to -15 °C and +10 or
+15 °C than the water used for calibration.
Measurements
Instruction Manual 45