Transcript Free Residual Chlorine Measurement

pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Free Residual Chlorine
Measurement
?
Why measure residual chlorine in
drinking water?
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IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Chlorine Chemistry
Free Chlorine = HOCl + OCl--
Combined Chlorine = NH2Cl + NHCl2 + NCl3
Total Chlorine = Combined Chlorine +
Free Chlorine
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IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Chlorine Chemistry
Cl2 + H2O
HOCl
HOCl + H+ + ClH+ + OCl--
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IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
% Distribution HOCl vs. pH
100
90
80
70
60
% HOCI
50
40
30
20
10
0
4
5
6
7
pH
8
9
10
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IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Measurement Methods
Colorimetric
Open /Electrode Buffered
Amperometric/Polarographic
High Resolution Redox
pH/ORP Method
Galvanic Sensor
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IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Colorimetric Systems
Operating Principle
Add buffer and indicator solution to a known
volume of water.
After mixing, measure wavelength of light
transmitted through sample to determine
color change and thus, amount of free
residual chlorine in the sample.
04/05/0
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www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Colorimetric Systems
Advantages
Price.
High pH is not a limiting factor.
EPA approved DPD measurement.
Disadvantages
Uses reagents.
Must use pumps, valves and capillary tubes.
Can only generate a new residual reading
every 2 1/2 minutes.
High maintenance.
No pH or temperature output.
04/05/0
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www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Open Electrode/Buffered Systems
Operating Principle
A known volume of sample water is pumped
into a chamber and buffered to a pH of 4.
Two bare electrodes are in contact with the
sample inside the chamber and based upon mV
readings, a free residual chlorine value is
derived.
04/05/0
4
www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Open Electrode/Buffered Systems
Advantages
High pH is not a limiting factor.
Disadvantages
Use of buffers.
Must use pumps and valves.
High maintenance.
Difficult start-up.
No pH or temperature output.
04/05/0
4
www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Amperometric/Polarographic
Membrane Sensor
Operating Principle
A sensor consisting of a membrane (which
allows HOCL to migrate through it), two
dissimilar metal electrodes, and an electrolyte
are submersed into the water sample.
A free residual chlorine reading is derived
based on mV changes experienced by the
sensor.
04/05/0
4
www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Amperometric/Polarographic
Membrane Sensor
Advantages
Ease of use
No reagents or buffers added
Disadvantages
No pH or temperature compensation
(OPTIONAL)
No flow regulation
No pH or temperature output
(OPTIONAL)
04/05/0
4
www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
High Resolution Redox
Operating Principle
Characterize free residual chlorine demand
based upon ORP values of the water sample.
04/05/0
4
www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
High Resolution Redox
Advantages
In some instances, does a better job of
determining residual chlorine demand.
Disadvantages
Does not measure free residual chlorine
directly.
Any oxidant present in water sample will
be read as an increase in free residual
chlorine.
04/05/0
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www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
IC Controls - pH/ORP Method
Operating Principle
Water flows through a Dual Flow Cell
consisting of an ORP and a PH sensor.
Microprocessor in the analyzer calculates the
free residual chlorine (HOCL+OCL-)
concentration by using a polynomial
formula. This calculation requires the
analyzer to know the measured ORP, PH and
temperature values.
04/05/0
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www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
IC Controls - pH/ORP Method
Advantages
No reagents or buffers added.
No moving parts.
pH and temperature compensated.
Easy to set up and calibrate.
Multiple measurement readouts/outputs.
Dedicated relay control for residual chlorine and pH.
Disadvantages
Does not measure free residual chlorine directly.
Any oxidant present in water sample will be read as an
increase in free residual chlorine.
04/05/0
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www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Model 875 Galvanic Free Chlorine
Operating Principle
A sensor consisting of a membrane (which
allows Cl2 to migrate through it), two
dissimilar metal electrodes, and an electrolyte
are submersed into the water sample.
A free residual chlorine reading is derived
based on mV changes experienced by the
sensor.
04/05/0
4
www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Model 875 Galvanic Free Chlorine
Advantages
Ease of use
No reagents or buffers added
Absolute Zero
Pretensioned Membrane Cap
Galvanic Technology
Disadvantages
Manual pH compensation
(now Available in 876)
04/05/0
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www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Model 875 Galvanic Free Chlorine
Polarographic
vs
IC Controls Galvanic
What's the difference?
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IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Polarographic
Applied voltage from the Cathode to the Anode.
Reaction of Chlorine at Cathode generates a current.
Output can go below zero; a value that does not exist.
Therefore, decreased accuracy in calibration and measurement
Anode
Cathode
Membrane
Cl2 Cl
O
O 22
Cl O O
2 2 2
V
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IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Galvanic
No applied Voltage. Chlorine is the fuel for the battery.
Therefore, absolute zero and better accuracy.
Anode
Cathode
Membrane
Cl2 Cl
O
O 22
Cl O O
2 2 2
04/05/0
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www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Recharging the Sensor
Over time the sensor internal will deplete and the
membrane and fill solution will need replacement.
Historically, this was a difficult process with creases
being formed in the membrane and air bubbles in the
fill solution which cause inaccurate readings. At
times the process could take up to 1 hour to replace a
membrane and put a sensor back on line.
The model 835 sensor provides ease of use which
includes fast, reliable and simple maintenance.
04/05/0
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IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Pre-Tensioned Membrane Cap
Membrane
Module
Maintenance is made easy
with the Pre-Tensioned
Membrane cap.
This system ensures there
are no air bubbles or creases
in the membrane cap which
will cause false inaccurate
readings.
Tip
Retainer
An easy process that allows
recharging and re-installation
in less than 5 minutes.
04/05/0
4
www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Model 875 Galvanic Free Chlorine
Galvanic Technology
Absolute Zero
No Reagents Required
Pre-Tensioned Membrane Cap
Proven Technology
Superior Design
Better Results
www.iccontrols.com
04/05/0
4
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS
pH / ORP
Conductivity
Dissolved Oxygen
Chlorine
Standards
Model 875 Galvanic Free Chlorine
875 Analyzer
875 Panel
835 Galvanic Sensor
04/05/0
4
www.iccontrols.com
IC Controls 875 Free Available Chlorine System
R1.0 © 2004 IC CONTROLS