Selecting Type Of Chlorine Measurement - Emerson Rosemount Analytical FCLi Instruction Manual

MODEL FCLi
5.5 SELECTING THE TYPE OF CHLORINE MEASUREMENT
5.5.1 Purpose
This section describes how to do the following:
1. Program the analyzer to measure free chlorine (and pH). This step is necessary because the Model FCLi ana-
lyzer can be used with other sensors to measure other chlorine oxidants. It can also be used to measure ORP
(oxidation reduction potential). When used in the Model FCLi, the analyzer should be programmed to meas-
ure either free chlorine (FCLi-01) or free chlorine and pH (FCLi-02).
2. Set manual pH correction to 7.00. This step is necessary because the analyzer can also be used to measure
free chlorine using a sensor that requires a continuous pH correction.
3. Determine the level of electronic filtering of the sensor current
4. Enable or disable dual slope calibration.
5. Make various pH measurement settings. The analyzer supplied with the Model FCLi is designed to be as ver-
satile as possible. For pH measurements using the FCLi, the following settings should be left at their default
values.
a. solution temperature correction
b. analyzer isopotential point
c. enable or disable glass impedance fault.
5.5.2 Definitions — Chlorine
1. FREE CHLORINE. Free chlorine is the result of adding sodium hypochlorite (bleach), calcium hypochlorite
(bleaching powder), or chlorine gas to fresh water. Free chlorine is the sum of hypochlorous acid (HOCl) and
hypochlorite ion (OCl - ).
2. TOTAL CHLORINE. Total chlorine is the sum of free and combined chlorine. Combined chlorine generally
refers to chlorine oxidants in which chlorine is combined with ammonia or organic amines.
3. MONOCHLORAMINE. Monochloramine (NH
chlorine. It is commonly used to disinfect drinking water.
4. pH CORRECTION. The analyzer supplied with the FCLi can also be used with a free chlorine sensor (the
Model 499ACL-01) that requires a continuous pH correction. The FCLi uses a chlorine sensor that does not
require pH correction (the Model 498CL-01). Set the pH correction to Manual and enter pH 7.00.
5. INPUT FILTER. Before converting the sensor current to a chlorine reading, the analyzer applies an input filter.
The filter reduces noisy readings, but increases the response time. The level of filtering is selected by choos-
ing the amount of time required for the display to reach 63% of a step change.
6. DUAL SLOPE CALIBRATION. The free chlorine sensor loses sensitivity at high concentrations of chlorine. The
FCLi analyzer has a dual slope feature that allows the user to compensate for the non-linearity of the sensor.
Cl) is the product of a chemical reaction between ammonia and
2
SECTION 5.0
PROGRAMMING THE ANALYZER
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