Emerson Rosemount FCL-01 Reference Manual page 59

Reference Manual
00809-0100-3412
Figure 5-1: Sensor current as a function of free chlorine concentration
A.
B. Sensor current
C.
D. Chlorine, ppm
E. Slope = sensor current/ppm chlorine
F. Full scale standard
G.
Any of the following makes a good zero standard:
• Commercially available bottled drinking water.
Note
Do not use distilled water
• Deionized water containing about 500 ppm sodium chloride. Dissolve about 0.5 grams
(⅛ teaspoonful) of table salt in 1.1 quart (1 liter) of water.
Note
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 full-scale standard 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 standards when taking and testing the grab
sample.
• Take the grab sample from a point as close to the Rosemount FCL as possible. Be sure
that taking the sample does not alter the flow of the sample to the unit. The ideal
Rosemount FCL 1056
i full scale
i zero
c stnd
Calibration
October 2023
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