Emerson Rosemount 1056, Инструкция по эксплуатации

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The following screen will appear if In Process Cal is
successful. The screen will return to the conductivity
Cal Menu.
This screen may appear if In Process Cal is unsuccessful.
The screen will return to the conductivity Cal Menu.
S1: 1.234µS/cm 25.0ºC
S2: 12.34pH 25.0ºC
S N InProcess Cal
Calibration
Error
Press EXIT
S1: 1.234µS/cm 25.0ºC
S2: 12.34pH 25.0ºC
S N InProcess Cal
Updated cell
constant:
3.01350/cm
7.6 Calibration — Chlorine
With a Chlorine measurement board and the appropriate sensor, Model 1056 can measure any of four variants of
Chlorine:
• Free Chlorine
• Total Chlorine
• Monochloramine
• pH-independent Free Chlorine
The section describes how to calibrate any compatible amperometric chlorine sensor. The following calibration
routines are covered in the family of supported Chlorine sensors:
• Air Cal
• zero Cal
• In Process Cal
7.6.1 Calibration — Free Chlorine
7.6.1.1 Description
A free chlorine sensor generates a current directly proportional to the concentration of free chlorine in the sam-
ple. Calibrating the sensor requires exposing it to a solution containing no chlorine (zero standard) and to a solu-
tion containing a known amount of chlorine (full-scale standard). The zero calibration is necessary because chlo-
rine sensors, even when no chlorine is in the sample, generate a small current called the residual current. The
analyzer compensates for the residual current by subtracting it from the measured current before converting the
result to a chlorine value. New sensors require zeroing before being placed in service, and sensors should be
zeroed whenever the electrolyte solution is replaced. Either of the following makes a good zero standard:
• Deionized water containing about 500 ppm sodium chloride. Dissolve 0.5 grams (1/8 teaspoonful) of table
salt in 1 liter of water. DO NOT USE DEIONIZED WATER ALONE FOR ZEROING THE SENSOR. THE
CONDUCTIVITY OF THE ZERO WATER MUST BE GREATER THAN 50 μS/cm.
• Tap water known to contain no chlorine. Expose tap water to bright sunlight for at least 24 hours.
The purpose of the In Process calibration is to establish the slope of the calibration curve. Because stable chlorine
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. Observe the following precautions when taking
and testing the grab sample.
• Take the grab sample from a point as close to the sensor as possible. Be sure that taking the sample does not alter
the flow of the sample to the sensor. It is best to install the sample tap just downstream from the sensor.
• Chlorine solutions are unstable. Run the test immediately after taking the sample. Try to calibrate the sensor
when the chlorine concentration is at the upper end of the normal operating range.
THIS SECTION DESCRIBES HOW TO CALIBRATE THE MODEL 1056 WITH A FREE CHLORINE SENSOR.
THE FOLLOWING CALIBRATION ROUTINES ARE COVERED.
Instruction Manual
LIQ-MAN-1056
Section 7.0: Calibration
April 2017