Endress+Hauser CCS140 User manual

Products Solutions Services
Operating Instructions
CCS140/141
Sensors for measuring free available chlorine
BA00058C/07/EN/14.18
71423117
2018-10-23

CCS140/141 Table of contents
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Table of contents
1 About this document ........... 4
1.1 Warnings ........................... 4
1.2 Symbols used ........................ 4
2 Basic safety instructions ....... 6
2.1 Requirements for the personnel ........ 6
2.2 Designated use ...................... 6
2.3 Workplace safety .................... 6
2.4 Operational safety ................... 6
2.5 Product safety ....................... 7
3 Product description ............. 7
3.1 Product design ....................... 7
4 Incoming acceptance and
product identification ......... 12
4.1 Incoming acceptance ................ 12
4.2 Product identification ................ 12
5 Installation .................... 14
5.1 Installation conditions ............... 14
5.2 Mounting the sensor ................ 15
5.3 Post-installation check ............... 17
6 Electrical connection .......... 17
6.1 Connecting the sensor ............... 18
6.2 Ensuring the degree of protection ..... 20
6.3 Post-connection check ............... 20
7 Commissioning ................ 21
7.1 Function check ..................... 21
7.2 Sensor polarization .................. 21
7.3 Sensor calibration ................... 21
8 Diagnostics and
troubleshooting ............... 23
9 Maintenance .................. 25
9.1 Maintenance schedule ............... 25
9.2 Maintenance tasks .................. 25
10 Repair .......................... 32
10.1 Spare parts ........................ 32
10.2 Return ............................ 32
10.3 Disposal ........................... 32
11 Accessories .................... 33
11.1 Device-specific accessories ............ 33
12 Technical data ................. 34
12.1 Input .............................. 34
12.2 Performance characteristics .......... 36
12.3 Environment ....................... 36
12.4 Process ............................ 36
12.5 Mechanical construction ............. 37
Index ................................. 38

About this document CCS140/141
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1 About this document
1.1 Warnings
Structure of information Meaning
LDANGER
Causes (/consequences)
If necessary, Consequences of non-
compliance (if applicable)
‣Corrective action
This symbol alerts you to a dangerous situation.
Failure to avoid the dangerous situation will result in a fatal or serious injury.
LWARNING
Causes (/consequences)
If necessary, Consequences of non-
compliance (if applicable)
‣Corrective action
This symbol alerts you to a dangerous situation.
Failure to avoid the dangerous situation can result in a fatal or serious injury.
LCAUTION
Causes (/consequences)
If necessary, Consequences of non-
compliance (if applicable)
‣Corrective action
This symbol alerts you to a dangerous situation.
Failure to avoid this situation can result in minor or more serious injuries.
NOTICE
Cause/situation
If necessary, Consequences of non-
compliance (if applicable)
‣Action/note
This symbol alerts you to situations which may result in damage to property.
1.2 Symbols used
Symbol Meaning
Additional information, tips
Permitted or recommended
Not permitted or not recommended
Reference to device documentation
Reference to page
Reference to graphic
 Result of a step

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1.2.1 Symbols on the device
Symbol Meaning
Reference to device documentation

Basic safety instructions CCS140/141
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2 Basic safety instructions
2.1 Requirements for the personnel
Installation, commissioning, operation and maintenance of the measuring system may be
carried out only by specially trained technical personnel.
‣The technical personnel must be authorized by the plant operator to carry out the specified
activities.
‣The electrical connection may be performed only by an electrical technician.
‣The technical personnel must have read and understood these Operating Instructions and
must follow the instructions contained therein.
‣Measuring point faults may be repaired only by authorized and specially trained personnel.
Repairs not described in the Operating Instructions provided must be carried out only
directly at the manufacturer's site or by the service organization.
2.2 Designated use
Drinking water, process water and bathing water must be disinfected through the addition of
appropriate disinfectants such as chlorine gas or inorganic chlorine compounds. The dosing
quantity must be adapted to continuously fluctuating operating conditions. Too low
concentrations in the water could jeopardize the effectiveness of the disinfection. Too high
concentrations can lead to signs of corrosion and have an adverse effect on the taste and
smell, while also generating unnecessary costs.
The sensor was specifically developed for this application and is designed for continuous
measurement of free chlorine in water. In conjunction with measuring and control equipment,
it allows optimal control of disinfection.
Use of the device for any purpose other than that described, poses a threat to the safety of
people and of the entire measuring system and is therefore not permitted.
The manufacturer is not liable for damage caused by improper or non-designated use.
2.3 Workplace safety
As the user, you are responsible for complying with the following safety conditions:
• Installation guidelines
• Local standards and regulations
Electromagnetic compatibility
• The product has been tested for electromagnetic compatibility in accordance with the
applicable European standards for industrial applications.
• The electromagnetic compatibility indicated applies only to a product that has been
connected in accordance with these Operating Instructions.
2.4 Operational safety
Before commissioning the entire measuring point:
1. Verify that all connections are correct.

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2. Ensure that electrical cables and hose connections are undamaged.
3. Do not operate damaged products, and protect them against unintentional operation.
4. Label damaged products as defective.
During operation:
‣If faults cannot be rectified:
products must be taken out of service and protected against unintentional operation.
2.4.1 Special instructions
‣Do not operate the sensors under process conditions where it is expected that osmotic
conditions will cause electrolyte components to pass through the membrane and into the
process.
2.5 Product safety
The product is designed to meet state-of-the-art safety requirements, has been tested, and
left the factory in a condition in which it is safe to operate. The relevant regulations and
European standards have been observed.
3 Product description
3.1 Product design
The sensor consists of the following functional units:
• Measuring chamber
– To protect the anode or cathode from the medium
– With a large volume of electrolyte for a long service life in combination with the large
anode and the small cathode
• Sensor shaft with
– Large anode
– Cathode embedded in plastic
– Optional temperature sensor
• Membrane cap with
– Robust PTFE membrane
– Special support grid between cathode and membrane for a defined and consistent
electrolyte film and thus a relatively constant indication even at varying pressures and
flows

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1
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5
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3
A0037109
1 Fixed cable
2 Sensor shaft
3 O-ring
4 Large anode, silver/silver chloride
5 Gold cathode
6 Measuring chamber
7 Membrane cap with dirt-repellent membrane
8 Screw cap for securing the membrane cap
3.1.1 Measuring principle
Free available chlorine levels are determined using hypochlorous acid (HOCl) in accordance
with the amperometric measuring principle.
The hypochlorous acid (HOCl) contained in the medium diffuses through the
sensor membrane and is reduced to chloride ions (Cl-) at the gold cathode. At the silver anode,
silver is oxidized to silver chloride. Electron donation at the gold cathode and electron
acceptance at the silver anode causes a current to flow which is proportional to the
concentration of free chlorine in the medium at constant conditions.
The concentration of hypochlorous acid (HOCl) depends on the pH value. An additional pH
measurement should be used to compensate for this dependency.
The transmitter uses the current signal to calculate the measured variable for concentration in
mg/l (ppm).
3.1.2 Effects on the measured signal
pH value
pH dependency
Molecular chlorine (Cl2) is present at pH values < 4. Consequently, hypochlorous acid (HOCl)
and hypochlorite (OCl– remain within the range of pH 4 to 11 as components of free chlorine.

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As hypochlorous acid splits up (dissociates) with an increasing pH value to form hypochlorite
ions (OCl–) and hydrogen ions (H+), the amounts of the individual components of free
effective chlorine change with the pH value. For example, if the proportion of hypochlorous
acid is 97 % at pH 6, it drops to approx. 3 % at pH 9.
For amperometric measurement using the chlorine sensor, only the amount of hypochlorous
acid (HOCl) is selectively measured. This works as a powerful disinfectant in an aqueous
solution. Hypochlorite (OCl–), however, is an extremely weak disinfectant. Therefore, when
used as a disinfectant at higher pH values, the effectiveness of chlorine is limited. Since
hypochlorite ions cannot pass through the sensor membrane, the sensor does not record this
part.
pH compensation of chlorine sensor signal
To calibrate and verify the chlorine measuring system, a colorimetric reference measurement
must be carried out using the DPD method. Free chlorine reacts with diethyl-p-
phenylendiamine to form a red dye. The intensity of the red color increases proportionally to
the chlorine content. For the DPD test, the sample is buffered to a specified pH value.
Therefore, the pH value of the sample is not taken into account in the DPD measurement. Due
to the buffer function in the DPD method, all components of free effective chlorine (HOCl and
OCl-) are detected and thus the total free chlorine is measured.
The chlorine sensor only measures the hypochlorous acid. If you select pH compensation in
the transmitter, the sum of hypochlorous acid and hypochlorite is calculated from the
measured signal and the pH value. This value corresponds to the DPD measurement.
When free chlorine is measured with pH compensation switched on, always perform
calibration in pH-compensated mode.
When you use pH compensation, the measured chlorine value displayed and output by the
device corresponds to the DPD value even if the pH value fluctuates. If no pH compensation is
used, the chlorine value of the DPD measurement corresponds only to the chlorine value of

Product description CCS140/141
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the sensor at the same pH value with respect to the calibration. Without pH compensation,
the chlorine measuring system must be recalibrated when the pH value changes.
%
100
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60
40
20
0
45 6 7 8 9 10 11
100
%
80
60
40
20
0
A
pH
OCl-
HOCl
C
B
A0002017
 1 Principle of pH compensation
A Measured value with pH compensation
B Measured value without pH compensation
C pH compensation
Accuracy of pH compensation
The accuracy of the pH-compensated measured chlorine value is derived from the sum of
several individual deviations (free chlorine, pH, temperature, DPD measurement etc.).
High levels of hypochlorous acid (HOCl) during chlorine calibration have a positive effect on
accuracy, whereas low levels of hypochlorous acid have a negative effect. The inaccuracy of
the pH-compensated measured chlorine value increases the greater the pH difference
between measuring mode and chlorine calibration or the more inaccurate the underlying
individual measured values are.
Calibration taking into account the pH value
For the DPD test, the sample is buffered to a specified pH value. In contrast to this,
amperometric measurement determines only the HOCl component.
During operation, pH compensation is effective up to a pH value of 9. However, there is
virtually no hypochlorous acid (HOCl) left at this pH value, and the measured current is very
low. At this point, pH compensation has the effect of increasing the measured HOCl value to