Calibration - Monochloromine - Emerson Rosemount 1066 Instruction Manual

Instruction Manual
LIQ-MAN-1066
9.6.3 Calibration – Monochloromine
A monochloramine sensor generates a current directly proportional to the concentration of
monochloramine in the sample. Calibrating the sensor requires exposing it to a solution
containing no monochloramine (zero standard) and to a solution containing a known amount of
monochloramine (full-scale standard). The zero calibration is necessary because monochloramine
sensors, even when no monochloramine is in the sample, generate a small current called the
residual or zero current. The transmitter compensates for the residual current by subtracting it
from the measured current before converting the result to a monochloramine value. New sensors
require zeroing before being placed in service, and sensors should be zeroed whenever the
electrolyte solution is replaced. The best zero standard is deionized water. The purpose of the In
Process calibration is to establish the slope of the calibration curve. Because stable
monochloramine standards do not exist, the sensor must be calibrated against a test run on a grab
sample of the process liquid. Several manufacturers offer portable test kits for this purpose.
To calibrate the chlorine sensor, access the Calibration screen by pressing ENTER from the main
screen, and press ENTER.
The following calibration routines are covered:
1. Zero Cal Zeroing the sensor in solution with zero total chlorine
2. Grab Cal Standardizing to a sample of known monochloramine concentration
To calibrate monochloramine:
1. Press the MENU button
2. Select Calibrate. Press ENTER.
3. Select Monochloramine. Press ENTER.
The adjacent screen will appear. To calibrate Monochloramine or
Temperature, scroll to the desired item and press ENTER.
The following sub-sections provide you with the initial display screen that appears for each
calibration routine. Use the flow diagram for Chlorine calibration at the end of Sec. 9 and the live
screen prompts to complete calibration.
The adjacent screen appears after selecting Monochloramine calibration:
Calibration
Section 9: Calibration
April 2017
1.234 µS/cm 25.0 ºC
SN Calibrate?
Monochloramine
Temperature
1.234 µS/cm 25.0 ºC
SN Calibration
Zero Cal
In Process Cal
79