BA00467C/07/EN/17.12
71208859

Products

Solutions

Valid as of:Softwareversion 01.04.00

Operating Instructions
Liquistation CSF48
Automatic sampler for liquid media
Calibration

ServicesAbout this manualThis manual describes how to calibrate the distribution arm and the sample volume. In addition,it also explains all the possible ways of calibrating and adjusting digital sensors with the
Memosens protocol.
This manual does not include the following:• Setup/General settings--> Operating Instructions BA00443C "Commissioning"• Display/Operation--> Operating Instructions BA00443C "Commissioning"• Inputs--> Operating Instructions BA00464C "Operation & settings"• Outputs--> Operating Instructions BA00464C "Operation & settings"• Sampling programs--> Operating Instructions BA00464C "Operation & settings"• Additional functions--> Operating Instructions BA00464C "Operation & settings"• Data management--> Operating Instructions BA00464C "Operation & settings"• Expert--> Internal Service Manual• Diagnostics--> Operating Instructions BA00463C "Maintenance & diagnostics"

Safety instructions! CAUTION
The cleaning system is not switched off during calibration or maintenance activities
Risk of injury due to medium or cleaning agent‣ If a cleaning system is connected, switch it off before removing a sensor from the medium.
‣ If you are not switching off the cleaning system because you wish to test the cleaning
function, wear protective clothing, goggles and gloves or take other appropriate measures.

Liquistation CSF48

Table of contents
1

Calibrating the distribution
arm . . . . . . . . . . . . . . . . . . . . . . . . 5

7

Oxygen sensors. . . . . . . . . . . . . 29

7.1

2

Calibrating the sample volume 6

2.1
2.2

Vacuum pump . . . . . . . . . . . . . . . . . . . . . . 6
Peristaltic pump . . . . . . . . . . . . . . . . . . . . . 9

7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9

Signal generation with amperometricsensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Calibration intervals . . . . . . . . . . . . . . . . . 30
Types of calibration . . . . . . . . . . . . . . . . . 31
Slope calibration . . . . . . . . . . . . . . . . . . . . 32
Calibration of the zero point . . . . . . . . . . 34
Sample calibration . . . . . . . . . . . . . . . . . . 35
Resetting the counter . . . . . . . . . . . . . . . . 36
Temperature adjustment . . . . . . . . . . . . . 36
Error messages when performing thecalibration . . . . . . . . . . . . . . . . . . . . . . . . . 37

3

Calibration and adjustment . . 10

3.1
3.2
3.3

Definitions . . . . . . . . . . . . . . . . . . . . . . . . 10
Terminology . . . . . . . . . . . . . . . . . . . . . . . 10
Notes on performing a calibration . . . . 13

4

pH sensors . . . . . . . . . . . . . . . . . 14

8

Chlorine sensors. . . . . . . . . . . . 38

4.1
4.2
4.3
4.4
4.5
4.6

Calibration intervals . . . . . . . . . . . . . . . . 14
Types of calibration . . . . . . . . . . . . . . . . . 15
Two-point calibration . . . . . . . . . . . . . . . 16
Single-point calibration . . . . . . . . . . . . . 17
Temperature adjustment . . . . . . . . . . . . 19
Error messages when performing thecalibration . . . . . . . . . . . . . . . . . . . . . . . . . 19

8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9

Calibration intervals . . . . . . . . . . . . . . . . . 38
Polarization . . . . . . . . . . . . . . . . . . . . . . . . 39
Types of calibration . . . . . . . . . . . . . . . . . 40
Reference measurement . . . . . . . . . . . . . 40
Slope calibration . . . . . . . . . . . . . . . . . . . . 41
Zero point calibration . . . . . . . . . . . . . . . . 41
Resetting the counter . . . . . . . . . . . . . . . . 42
Temperature adjustment . . . . . . . . . . . . . 43
Error messages when performing thecalibration . . . . . . . . . . . . . . . . . . . . . . . . . 43

9Ion-selective sensors . . . . . . . . 44

9.1
9.2
9.3

Types of calibration . . . . . . . . . . . . . . . . . 44
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Ammonium, nitrate, potassium,chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
ORP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Temperature adjustment . . . . . . . . . . . . . 48
Error messages when performing thecalibration . . . . . . . . . . . . . . . . . . . . . . . . . 49

5

ORP sensors. . . . . . . . . . . . . . . . 20

5.1
5.2
5.3
5.4
5.5

Types of calibration . . . . . . . . . . . . . . . . . 20
Single-point calibration . . . . . . . . . . . . . 20
Two-point calibration (only ORP %) . . . 21
Temperature adjustment . . . . . . . . . . . . 21
Error messages when performing thecalibration . . . . . . . . . . . . . . . . . . . . . . . . . 22

6

Conductivity sensors . . . . . . . . 23

6.1
6.2
6.3

Types of calibration . . . . . . . . . . . . . . . . . 23
Cell constant . . . . . . . . . . . . . . . . . . . . . . . 23
Air set (residual coupling, only inductive
sensors) . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Installation factor (only inductive
sensors) . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Temperature adjustment . . . . . . . . . . . . 27
Error messages when performing thecalibration . . . . . . . . . . . . . . . . . . . . . . . . . 28

6.4
6.5
6.6

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9.4
9.5
9.6

10 Turbidity and solids sensor. . . 50
10.1 Types of calibration . . . . . . . . . . . . . . . . . 50
10.2 Turbidity and solids . . . . . . . . . . . . . . . . . 51
10.3 Temperature adjustment . . . . . . . . . . . . . 54
10.4 Error messages when performing thecalibration . . . . . . . . . . . . . . . . . . . . . . . . . 55

Liquistation CSF48

11 SAC sensor . . . . . . . . . . . . . . . . 56
11.1 Types of calibration . . . . . . . . . . . . . . . . 56
11.2 SAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
11.3 Temperature adjustment . . . . . . . . . . . . 59
11.4 Error messages when performing thecalibration . . . . . . . . . . . . . . . . . . . . . . . . 60

12 Nitrate sensors . . . . . . . . . . . . . 61
12.1 Types of calibration . . . . . . . . . . . . . . . . 61
12.2 Nitrate . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
12.3 Temperature adjustment . . . . . . . . . . . . 64
12.4 Error messages when performing thecalibration . . . . . . . . . . . . . . . . . . . . . . . . 65

13 Calibration accessories . . . . . . 66
13.1 pH calibration buffer . . . . . . . . . . . . . . . 66
13.2 ORP buffer . . . . . . . . . . . . . . . . . . . . . . . . 66
13.3 Conductivity . . . . . . . . . . . . . . . . . . . . . . . 67
13.4 Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
13.5 Chlorine . . . . . . . . . . . . . . . . . . . . . . . . . . 67
13.6 ISE and nitrate . . . . . . . . . . . . . . . . . . . . . 68
13.7 Nitrate . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
13.8 SAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Index . . . . . . . . . . . . . . . . . . . . . 69

4

Liquistation CSF48

1

Calibrating the distribution arm

Calibrating the distribution arm

It is only possible to calibrate the distribution arm in the version with multiple bottles.
The distribution arm must be calibrated if:• The distribution arm motor has been replaced• Error message "F236 Distribution arm" appears on the display
1. Select the number of bottles in the "Setup/Basic setup" menu.
2. Proceed as follows to calibrate the distribution arm:
Path: Menu/Calibration active
Function

Options

Info

ActionThe reference run is started. The reference point isin the middle at the front.
For versions with distributor plate, the reference
point is at the arrow in the middle of the plate. For
versions with distribution assembly the reference
point is between bottle number 1 and the last one.

Distribution arm
Go to ref. point

With Adjust you can correct the distribution arm if the unit does not move to the reference point correctly. Use
the two arrow keys to correct the position.

3. Afterwards perform a distribution arm test in the "Diagnostics/Systemtest/Reset/Distributionarm" menu.

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5Calibrating the sample volume

2

Calibrating the sample volume

2.1

Vacuum pumpLiquistation CSF48

The desired sample volume is set by manually adjusting the dosing tube.

5

4
3

6

2
1

Fig. 1: Vacuum pump
1
2
3
4
5
6

a0013896

Outlet hose
Dosing chamber
Dosing chamber cover
Air hose connection
Lock for intake hoseThread adapter nut for intake hose

Proceed as follows to calibrate the sample volume:
1. Check the sample volume set under Menu/Setup/General settings/Sampling/Dosing
volume.
2. Release the thread adapter nut on the intake hose (item 6).
3. Turn the intake hose to the "open" position at the hose lock (item 5) and remove the hosefrom above.
4. Release the air hose (item 4) and remove the dosing chamber (item 2) from the front alongwith the outlet hose (item 1).
5. Open the bayonet lock (item 3) and open the dosing chamber.

6

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Calibrating the sample volume

1
2
3

Dosing tube
Allen screw
Air hose connection

3

2
1

Fig. 2: Vacuum pumpa0014128

1.
2.

Release the 2mm Allen screw with the key provided.
Set the sample volume by adjusting the dosing tube. Secure the dosing tube with the screw.
Use the white scale (A) to dose without pressure.
Use the blue scale (B) to dose with pressure.

3.

Reinstall the parts in reverse order. Make sure that the contacts of the conductivity sensors
are in the correct position.
Check that the dosing tube is set correctly by triggering a manual sampling routine.

4.

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Calibrating the sample volume

Liquistation CSF48

2.1.1 Capacitance sample sensor(Only for version with vacuum pump)
The capacitance sample sensor has been factory-adjusted, therefore, when firstcommissioning no adjustment is necessary. Adjust the sensor if the trigger sensitivity is
too low. This is the case if the sample covers more than 30% of the sensor (item 1).
The yellow and green lights (item 2) at the capacitance sample sensor are on.
Adjust the capacitance sample sensor as follows:
1. Make sure the dosing chamber is empty.
2. With the supplied screwdriver turn the adjusting screw (item 3) to the right (clockwise)
until the yellow light goes out.
3. Then turn slightly back to the left (counterclockwise) until the yellow light is on again. At
this point the sensor is adjusted to the most sensitive setting.
4. In order to verify the settings perform a manual sampling.
5. If the setting is too sensitive (causing e.g. false triggering, or the yellow light remains dark
after sampling), adjust the sensor to a more insensitive setting by turning the adjustingscrew further to the left.

Fig. 3: Adjust the capacitance sample sensor
1
2
3

8

a0015413

SensorYellow and green light
Adjusting screw

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Liquistation CSF48

2.2

Calibrating the sample volume

Peristaltic pump
In order to calibrate the sample volume, a measurement beaker with a volume of at least
200 ml is required.
Proceed as follows to calibrate:

Path: Menu/Calibration active
Function

Options

Info

Distributor position

Options- Front- Bottle x- BackSelect the distributor position.

Sample volume

20 to 2000 ml

Set the sample volume.

Sample volume
1-point calibration

Factory setting
100 mlStart sampling

ActionCheck whether the sample volume is correct. Use
Use Yes to repeat the sampling.

The progress of the sampling operation isdisplayed.
No to enter the sample volume actually taken, e.g. 110 ml.

2-point calibration
Use 2-point calibration for levels that fluctuate greatly.
The second sampling point must be either higher or lower (height difference of at least 1 m).
Distributor position

Options- Front- Bottle x- BackSelect the distributor position.

Sample volume

20 to 2000 ml

Set the sample volume.

Factory setting
100 mlStart 1. sampling

ActionCheck whether the sample volume is correct. Use
Use Yes to repeat the sampling.
Start 2. sampling

ActionCheck whether the sample volume is correct. Use
Use Yes to repeat the sampling.

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The progress of the sampling operation isdisplayed.
No to enter the sample volume actually taken, e.g. 110 ml.

The progress of the sampling operation isdisplayed.
No to enter the sample volume actually taken, e.g. 110 ml.

9Calibration and adjustment

Liquistation CSF48

3

Calibration and adjustment

3.1

Definitions

Calibration (as per DIN 1319):
A calibration is defined as a set of operations that establish the relationship between themeasured value or expected value of the output variable and the related true or correct value ofthe measured variable (input variable) for a measuring system under specified conditions.
A calibration does not alter the performance of the measuring device.
Adjustment
An adjustment corrects the value displayed by a measuring device, in other words themeasured/displayed value (the actual value) is corrected so that the reading agrees with thecorrect, set value.
The value determined during calibration is used to calculate the correct measured value andsaved in the sensor.

3.2

Terminology

3.2.1 Zero point and slope
Using a mathematical function, the transmitter converts the input signal of the sensor y (rawmeasured value) to the measured value x. In many cases, this function is a simple linear of theform y = a + b . x.
The linear element "a" is usually equivalent to the zero point and the factor "b" is the slope of theline.

Fig. 4: Linear functionab10

a0013593

Zero point
Slope

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Liquistation CSF48

Calibration and adjustment

The Nernst equation, which is used to calculate the pH value, is a typical linear relationship:
Ui = U0 - 2.303 RT pH
F
pH = -lg(aH+), aH+ ... activity of the hydrogen ions
Ui ... raw measured value in mV
U0 ... zero point (=voltage at pH 7)
R ... relative gas constant (8.3143 J/molK)
T ... temperature [K]F ... Faraday constant (26.803 Ah)
The slope of the Nernst equation (-2.303RT/F) is known as the Nernst factor and has thevalue -59.16 mV/pH at 25 ˚C.
3.2.2 Delta slope
The device determines the difference in the slope between the calibration currently valid and thelast calibration. Depending on the sensor type, this difference is an indicator of the condition of
the sensor. The smaller the slope, the less sensitive the measurement, and the accuracy
deteriorates particularly in the low measuring range.
Depending on the operating conditions, users can define limit values that represent the still
tolerable absolute values of the slope and/or slope differentials. If the limit values are exceeded,
maintenance must be performed on the sensor at the very least. The sensor must be replaced if
the insensitivity problems persist after maintenance has been carried out.

Fig. 5: Delta slope
Blue
Red
b

a0013594

Last calibration
Calibration currently valid
Delta slope

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Calibration and adjustment

Liquistation CSF48

3.2.3 Delta zero point
The device determines the difference between the zero points or operating points (ISFET sensor)of the last and second-last calibration. A shift in the zero point or operating point (offset) does
not alter the sensitivity of the measurement. However, if the offset is not corrected this canfalsify the measured value.
As with the slope, you can also define and monitor limit values for the offset. If the limit values
are exceeded, this means that maintenance must be performed on the sensor. For example, you
may have to eliminate a blockage in the reference for the pH sensor.

a0013595

Fig. 6: Delta zero point or operating point (ISFET sensor)
a1
a2
a

12

Zero point (operating point) of the second-lastcalibration
Zero point (operating point) of the last calibration
Delta zero point (operating point)

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Liquistation CSF48

3.3

Calibration and adjustment

Notes on performing a calibration

The following rules apply for all parameters:• Calibrate in a way that reflects conditions in the process.
– If the process medium is constantly moving, also move the calibration solution accordingly(e.g. use a magnetic stirrer if calibrating in the laboratory).
– If your medium is relatively stationary, calibrate in solutions that are also stationary.
• Make sure that the samples are homogeneous for reference measurements, sample
calibration etc.
• Avoid changes in the medium samples resulting from ongoing biological activity.
Example: Use outlet water instead of a sample from the aeration basin for nitrate calibration.
• Use the same menu settings as those in the process to perform the calibration.
Example: If you automatically compensate for the temperature effect during pH
measurement, switch on automatic temperature compensation for the calibration also.
It is advisable to perform the laboratory calibration using the "Memobase" databasesoftware (--> "Accessories"). This improves the availability of your measuring points and all
the calibration and sensor data records are stored securely in the database.

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pH sensors

Liquistation CSF48

4

pH sensors

4.1

Calibration intervals

4.1.1 Specifying the intervals
The service life of a pH glass electrode is limited. This is due, in part, to the deterioration andaging of the pH-sensitive membrane glass. This aging causes the gel-like layer to change andbecome thicker over time.
Symptoms of aging include:• Higher membrane resistance• Slow response• Decrease in the slope
A change in the reference system (e.g. due to contamination, i.e. unwanted redox reactions at
the reference electrode) or electrolyte solution dissolving away in the reference half cell canchange the reference potential, which, in turn, causes a zero point shift in the measuring
electrode.
To ensure a high level of accuracy, it is important to readjust the pH sensors at set intervals.
The calibration interval depends heavily on the area of application of the sensor, as well as therequired level of accuracy and reproducibility. The calibration interval can vary between daily
and once every few months.
Defining the calibration interval for the process
1. Check the sensor with a buffer solution, e.g. pH 7.
 Proceed as specified in Step 2 only if the value deviates from the set point. No
calibration/adjustment is necessary if the value is within the defined deviation tolerance
range (see the Technical Information for the sensor).
2. Calibrate and adjust the sensor.
3. After 24 hours, check again with the buffer solution.
a.

If the deviation is within the permitted tolerance range, increase the checking
interval by doubling it for example.

b.

If the deviation is larger, you must shorten the interval.

3. Continue to proceed as defined in Steps 2 and 3 until you have identified the suitableinterval.

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pH sensors

Monitoring the calibration‣ Define the limit values for monitoring the slope and zero point differentials(Menu/Setup/Inputs/pH/Extended setup/Diagnostics settings/Delta slope or Delta zero
point).
 These limit values depend on the process and must be determined by empirical means.

During calibration a diagnostics message is displayed if the defined warning limits have been
exceeded. You then have to service the sensor by cleaning the sensor or reference, or byregenerating the glass membrane.
You have to replace the sensor if warning messages continue to be displayed despite themaintenance measure.
4.1.2 Monitoring the calibration interval
Once you have established the calibration intervals for your process, you can also have the device
monitor them.
Two functions are available to monitor the calibration interval:
1. Calibration timer (Menu/Setup/Inputs/<Sensor type>/Extended setup/Calib.
settings/Calibration timer) You specify the calibration interval and the controller generates a diagnostics message
once the set time has elapsed.You then recalibrate the sensor or replace it with aprecalibrated sensor.
The timer is reset with the new calibration.
2. Calibration validity (Menu/Setup/Inputs/<Sensor type>/Extended setup/Calib.
settings/Calib. expiration date) You set time limits to specify how long a calibration should be regarded as valid.
Memosens sensors save all the calibration data. In this way it is easy to see whether thelast calibration took place in the specified timeframe and is therefore still valid. This isparticularly advantageous when working with precalibrated sensors.

4.2

Types of calibration

The following types of calibration are possible:• Two-point calibration– With calibration buffers– Entry of data for the slope, zero point and temperature• Single-point calibration– Entry of an offset or a reference value– Sample calibration with laboratory comparative value• Temperature adjustment by entering a reference value

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pH sensors

4.3

Liquistation CSF48

Two-point calibration

4.3.1 Applications and requirements
Two-point calibration is the preferred method for pH sensors, particularly in the following
applications:• Municipal and industrial wastewater• Natural waters and drinking water• Boiler feedwater and condensates• Beverages
Calibrating with buffers with pH 7.0 and 4.0 is recommended for most applications.
Alkaline buffer solutions have the disadvantage that carbon dioxide from the air can alter thepH value of the buffer on the long term. If calibrating with alkaline buffers it is best to do so inclosed systems, such as flow assemblies or retractable assemblies with a rinse chamber, tominimize the effect of air.
4.3.2 With calibration buffers
You use calibration buffers to perform two-point calibration. The quality buffers supplied
by Endress+Hauser are certified and measured in an accredited laboratory. The
accreditation (DAR registration number "DKD-K-52701") confirms that the actual values
and the maximum deviations are correct and traceable.
To calibrate the sensor, remove it from the medium and calibrate it in the laboratory. Since
Memosens sensors save the data, you can always work with "precalibrated" sensors and do nothave to stop monitoring the process to perform a calibration.
1. Go to the "CAL/2-pnt. calibration" menu.
2. Follow the instructions on the display.
3. Press "OK" after you have immersed the sensor into the first buffer.
 The system starts calculating the measured value for the first buffer. Once the stability
criterion is met, the measured value is displayed in mV.
4. Continue to follow the instructions.
5. Press "OK" after you have immersed the sensor into the second buffer.
 The system starts calculating the measured value for the buffer. Once the stability
criterion is met, the measured values of the two buffers and the calculated values for theslope and zero point are displayed.
6. Select "OK" when you are asked to accept the calibration data for adjustment.
7. Put the sensor back into the medium and press "OK" again.
 This deactivates the hold and the system starts measuring again.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

16

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Liquistation CSF48

pH sensors

Only use calibration buffers once.
4.3.3 Entering data for the zero point, slope and temperature
You enter the slope, zero point and temperature manually. The function for determining
the pH value is calculated from these values. Thus, the data entry returns the same result
as two-point calibration.

‣ You must determine the slope, zero point and temperature in an alternative way.
1. Go to the "CAL/Data input" menu.
 The slope, zero point and temperature are shown on the display.
2. Select each value one after another and then enter your desired numerical value.
 Since you are entering all the variables for the Nernst equation directly, no additional
information is displayed by the controller.
3. Select "OK" when you are asked to accept the calibration data for adjustment.
You can cancel the calibration any time by pressing the "ESC" key. No new data are then used toadjust the sensor.

4.4Single-point calibration

4.4.1 Applications and requirements
Single-point calibration is particularly useful if the deviation of the pH value from a reference
value, and not the absolute pH value itself, is of interest to the user. Applications for single-pointcalibration include:• Process control• Quality assurance
Fluctuations in the process value should not exceed ±0.5 pH and the process temperature mustremain relatively constant. As the measuring range is limited as a result, it is possible to set theslope to -59 mV/pH (at 25 ˚C).
To adjust the sensor, you enter an offset or a reference value.
Alternatively, you can also use the "sample calibration". Here, you take a sample from the process
and determine the pH value in the laboratory. In the case of the laboratory sample, you must
make sure that the pH value is determined at the process temperature.

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Liquistation CSF48

4.4.2 Sample calibration
With this type of calibration, you take a sample of the medium and determine its pH value(at process temperature) in the laboratory. You then use this laboratory value to adjust thesensor. This does not change the slope of the calibration function.
1. Go to the "CAL/.../Sample calibration" menu.
2. Follow the instructions on the display.
3. Press "OK" after you have taken the sample.
 The following message appears on the display:
Sample calibration.
4. Press the navigation button after you have determined the laboratory value.
 A line appears where you can enter the laboratory value.
5. Enter your laboratory measured value here and then go toContinue.

 The measured value, laboratory value and the resulting offset (zero point for ISE) aredisplayed.
6. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.
4.4.3 Entering the offset or reference value
You either enter an offset or a (reference) measured value calculated beforehand. This
then shifts the calibration function along the X-axis (pH). The slope is not affected.
1.Go to the "CAL/1-pnt. calibration" menu.
2. Decide which value you want to enter:a.

Offset Enter the desired offset. Once accepted, the value you entered immediately affects
the "Meas. value".

b.

Meas. value
 Enter the desired measured value. Once accepted, the value you entered
immediately affects the "Offset".

3. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

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4.5

pH sensors

Temperature adjustment

1. Determine the temperature of your process medium with an alternative measurement, e.g.
a precision thermometer.
2. Go to the "CAL/<Sensor type>/Temperature adjustment" menu.
3. Leave the sensor in the process medium and keep clicking "OK" until temperature
measurement is started via the sensor.
4. Enter the reference temperature from the alternative measurement. You can either enter
the absolute value or an offset for this purpose.
5. Once you have entered your data, click "OK" until the new data have been accepted.
 This completes temperature sensor adjustment.

4.6

Error messages when performing the calibration

Display message

Causes and possible remedial measures

The calibration is invalid. Do you want to start a new
calibration?
Slope out of tolerance.
Zeropoint out of tolerance.
Sample concentration too low.

The calibration buffer is contaminated or the pH value is nolonger within the permitted limits. As a result, the permitted
measured value deviation is exceeded.
• Check the expiry date
• Use a fresh buffer
Incorrect buffers used. As a result, the buffer recognition
function - for example - does not work correctly.
• pH values of the buffers are too close together, e.g. pH 9
and 9.2• Use buffers with a larger pH difference
Sensor aging or contaminated. As a result, the permitted limit
values for the slope and/or zero point are exceeded• Clean the sensor• Adjust the limit values• Regenerate or replace the sensor

The stability criterion is not fulfilled. Do you want torepeat the last step?

The measured value or temperature is not stable. As a result,the stability criterion is not met.
• Keep the temperature constant during calibration• Replace the buffer• Sensor old or contaminated. Clean or regenerate.
• Adjust the stability criteria(Menu/Setup/Inputs/<Electrode slot>/Calib.
settings/Stability criteria)

Calibration aborted. Please clean sensor before
immersing in process medium. (Hold will be disabled)

The user has aborted the calibration.

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5

ORP sensors

5.1

Types of calibration

Liquistation CSF48

The following types of calibration are possible:• Two-point calibration with samples of medium (only Main value = "%")• Single-point calibration with calibration buffer• Entry of data for an offset• Temperature adjustment via reference value

5.2

Single-point calibration

5.2.1 General information
The buffers contain ORP pairs with a high exchange current density. Such buffers have theadvantage of higher accuracy levels, better reproducibility and faster measurement response
times.
Temperature compensation does not take place when measuring the ORP since the thermal
behavior of the medium is not known. However, the temperature is indicated with themeasurement result and for this reason it makes sense to adjust the temperature sensor atprocess-dependent intervals.
5.2.2 Single-point calibration with calibration buffers
With this type of calibration, you work with calibration buffers, e.g. ORP buffers fromEndress+Hauser. For this purpose, you remove the sensor from the medium and calibrate
it in the laboratory. Since Memosens sensors save the data, you can always work with"precalibrated" sensors and do not have to stop monitoring the process for extended periods
to perform a calibration.
1. Go to the "CAL/1-pnt. calibration" menu.
2. Follow the instructions on the display.
3. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

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ORP sensors

5.2.3 Entering data for an offset
You enter the offset directly with this type of calibration. Use the measured value of areference measurement, for example, to determine the offset.
1. Go to the "CAL/Data input" menu.
 The current offset is displayed.
2. Decide whether you want to keep this value or enter a new value.
3. Enter the new offset.
4. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

5.3

Two-point calibration (only ORP %)You must adapt the sensor to your process to obtain useful ORP % values. This is achieved
through two-point calibration. The two calibration points are characteristic of the mostimportant states your medium can assume in the process.
You require two different compositions of your medium that represent the characteristic
limits of your process (e.g. 20% and 80% value).
The absolute value in mV is not relevant for the ORP % measurement.

1. Go to the "CAL/Redox/2-pnt. calibration" menu.
2. Follow the instructions on the display.
3. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

5.4

Temperature adjustment

1. Determine the temperature of your process medium with an alternative measurement, e.g.
a precision thermometer.
2. Go to the "CAL/<Sensor type>/Temperature adjustment" menu.
3. Leave the sensor in the process medium and keep clicking "OK" until temperature
measurement is started via the sensor.
4. Enter the reference temperature from the alternative measurement. You can either enter
the absolute value or an offset for this purpose.
5. Once you have entered your data, click "OK" until the new data have been accepted.
 This completes temperature sensor adjustment.

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5.5

Liquistation CSF48

Error messages when performing the calibration

Display message

Causes and possible remedial measures

The calibration is invalid. Do you want to start a new
calibration?

The calibration buffer is contaminated or the ORP potential is
no longer within the permitted limits. As a result, thepermitted measured value deviation is exceeded.
• Check the expiry date
• Use a fresh buffer

The stability criterion is not fulfilled. Do you want torepeat the last step?

The measured value is not stable. As a result, the stability
criterion is not met.
• Replace the buffer• Sensor old or contaminated. Clean or regenerate.
• Adjust stability criteria (Menu/Setup/Inputs/pH/Calib.
settings/Stability criteria)

Calibration aborted. Please clean sensor before
immersing in process medium. (Hold will be disabled)

The user has aborted the calibration.

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Conductivity sensors

6

Conductivity sensors

6.1

Types of calibration

The following types of calibration are possible:• Cell constant with calibration solution• Installation factor (only inductive sensors)• Air set (residual coupling, only inductive sensors)• Temperature adjustment via reference value

6.2

Cell constant

6.2.1 General information
A conductivity measuring system is generally calibrated in such a way that the exact cell
constant is determined or checked using suitable calibration solutions. This process is describedin the standards EN 7888 and ASTM D 1125, for example, and the method for producing a
number of calibration solutions is explained. Another alternative is to purchase international
calibration standards from national measurement institutes. This is particularly important in
the pharmaceutical industry, which requires a calibration to be traced to internationallyrecognized standards. To calibrate its testing units, Endress+Hauser uses special referencematerial (SRM) from the US National Institute of Standards and Technology (NIST).
6.2.2 Calibrating the cell constant
You enter a reference value for the conductivity with this type of calibration. In addition,
you specify how the system should compensate for the influence of temperature. In the
result, the controller calculates a new cell constant for the sensor.
1. Go to the "CAL/Cell constant" menu.
2. Work your way through the menu functions that follow.
3. Start the calibration.
Path: CAL/Conductivity/Cell constant
Function

Options

Info

Current cell const.

Read only

Value currently saved in the sensor

Temp. compensation

Options• No• Yes

As an alternative to the compensated conductivity (Yes)
you can also determine the cell constant by calibrating
the uncompensated conductivity (No).

Factory setting
Yes

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Conductivity sensors

Liquistation CSF48

Path: CAL/Conductivity/Cell constant
Function

Options

Info

Coeff. Alpha0.00 to 20.00 %/K

Temp. compensation = "Yes"

Factory setting
Depends on the sensor

The alpha coefficients and alpha reference temperaturesof Endress+Hauser can be found in the documentation
supplied with the calibration solutions.
Enter the appropriate values.

Alpha ref. temp.

-5.0 to 100.0 ˚C(23.0 to 212.0 ˚F)Factory setting
25.0 ˚C (77.0 ˚F)

Temp. source

Options• Sensor• Manual
Factory setting
SensorMedium temperature-50.0 to 250.0 ˚C(-58.0 to 482.0 ˚F)Factory setting
25.0 ˚C (77 ˚F)Conductivity ref.

0.000 to 2000000 μS/cm
Factory setting
0.000 μS/cm

Decide how you want to compensate the medium
temperature:• Automatically using the temperature sensor of yoursensor• Manually by entering the medium temperatureTemp. source = "Manual"Enter the temperature of your medium.

Temp. compensation ="Yes"Enter the compensated conductivity of your calibration
solution here.
Temp. compensation ="No"
Enter the uncompensated conductivity of yourcalibration solution here.

Start calibration

Start the calibration. Follow the instructions on the display.

You can cancel the calibration any time by pressing the "ESC" key. No new data are then used toadjust the sensor.

6.3

Air set (residual coupling, only inductive sensors)

While the calibration line goes through zero for physical reasons in the case of conductive
sensors (a current flow of 0 corresponds to a conductivity of 0), when working with inductive
sensors, the residual coupling between the primary coil (transmitter coil) and secondary coil(receiver coil) must be taken into account or compensated for. The residual coupling is not only
caused by the direct magnetic coupling of the coils but also by crosstalk in the supply cables. For
this reason, the process of commissioning an inductive sensor always starts with an "air set".
Here, the sensor is connected to the transmitter with the cables provided, held in air in a dry
state (zero conductivity) and an air set calibration is performed at the transmitter.
The cell constant is then determined using a precise calibration solution, as is the case with
conductive sensors.
Sensors with a Memosens protocol are already calibrated at the factory and their residual
coupling generally does not have to be adjusted on site.

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6.4

Conductivity sensors

Installation factor (only inductive sensors)

In confined installation conditions, the wall affects conductivity measurement in the liquid.
The installation factor compensates for this effect. The transmitter corrects the cell constant by
multiplying by the installation factor.
The size of the installation factor depends on the diameter and the conductivity of the pipe
nozzle, as well as the distance between the sensor and the wall.
If there is a sufficient distance between the wall and the sensor (a > 15 mm (0.59"), from
DN 80), the installation factor f does not have to be taken into consideration (f = 1.00).
If distances from the wall are smaller, the installation factor is bigger for electrically insulating
pipes (f >1), and smaller for electrically conductive pipes (f < 1).
It can be measured using calibration solutions, or a close approximation determined from thefollowing diagram.
f

1.40
2
1.20

1.00
1
0.80
0

10

15

20

25

0.20

0.39

0.59

0.79

0.98 a [inch]

Fig. 7: Relation between the installation factor f and the wall distance1
2

a [mm]

5

a0005441

Electrically conductive pipe wall
Electrically insulating pipe wall

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Conductivity sensors

Liquistation CSF48

6.4.1 Calibrating the installation factor
1. Go to the "CAL/Cond i/Inst. factor/Calibration" menu.
2. Work your way through the menu functions that follow.
Path: CAL/Cond i/Inst. factor/Calibration
Function

Options

InfoCur. inst. factor

Read only

Value currently saved in the sensor

Temp. compensation

Options• No• Yes

As an alternative to the compensated conductivity (Yes)
you can also determine the cell constant by calibrating
the uncompensated conductivity (No).

Factory setting
Yes
Coeff. Alpha

Alpha ref. temp.

0.00 to 20.00 %/K

Temp. compensation = "Yes"

Factory setting
Depends on the sensor

The alpha coefficients and alpha reference temperaturesof Endress+Hauser can be found in the documentation
supplied with the calibration solutions.
Enter the appropriate values.

-5.0 to 100.0 ˚C(23.0 to 212.0 ˚F)Factory setting
25.0 ˚C (77.0 ˚F)

Temp. source

Options• Sensor• Manual
Factory setting
SensorMedium temperature-50.0 to 250.0 ˚C(-58.0 to 482.0 ˚F)Factory setting
25.0 ˚C (77 ˚F)Conductivity ref.

0.000 to 2000000 μS/cm
Factory setting
0.000 μS/cm

Decide how you want to compensate the medium
temperature:• Automatically using the temperature sensor of yoursensor• Manually by entering the medium temperatureTemp. source = "Manual"Enter the temperature of your medium.

Temp. compensation ="Yes"Enter the compensated conductivity of your calibration
solution here.
Temp. compensation ="No"
Enter the uncompensated conductivity of yourcalibration solution here.

Start calibration

Start the calibration. Follow the instructions on the display.

You can cancel the calibration any time by pressing the "ESC" key. No new data are then used toadjust the sensor.

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Conductivity sensors

6.4.2 Entering the installation factor
1. Go to the "CAL/Cond i/Inst. factor/Entry" menu.
 The installation factor currently used is displayed.
2. New inst. factor: Enter the installation factor, which you took from  å 7for example.
3. Start the calibration.
You can cancel the calibration any time by pressing the "ESC" key. No new data are then used toadjust the sensor.

6.5

Temperature adjustment
The temperature sensor has to be calibrated at regular intervals to ensure the measured
value is not falsified by incorrect temperature measurement.

1. Go to the "CAL/Conductivity/Temperature adjustment" menu.
 The offset (of the last calibration) and the actual temperature value are shown on thedisplay.
2. Mode Decide which mode to use for temperature adjustmenta.

1-point calibration
 You measure the medium temperature with a reference measurement and use thisvalue to adjust the temperature sensor.

b.

2-point calibration
 You use two samples of different temperatures.

c.

Table
 Adjustment based on data entries. You enter value pairs comprising the measured
temperature of the temperature sensor and the related reference temperature. The
temperature function is calculated from these value pairs. Press "SAVE" once you
have entered all the points and select "OK" to confirm you want to accept thecalibration data.

4. Follow the instructions on the display.
5. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No new data are then used toadjust the sensor.

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6.6

Liquistation CSF48

Error messages when performing the calibration

Display message

Causes and possible remedial measures

The calibration is invalid. Do you want to start a new
calibration?

Calibration solution exhausted. As a result, the permitted
measured value deviation is exceeded• Check the expiry date
• Use a fresh calibration solution

Currently no calibration possible due to sensor failure.

Sensor communication problem• Replace sensor• Contact the Service Department

Calibration aborted. Please clean sensor before
immersing in process medium. (Hold will be disabled)

The user has aborted the calibration.

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7

Oxygen sensors

7.1

Signal generation with amperometric sensors

Oxygen sensors

The amperometric oxygen sensor is based on the reduction of oxygen at the noble metal cathodeof a system filled with electrolyte.
Oxygen coming from the medium (e.g. air) diffuses through a membrane into the electrolyte
film and is reduced at the cathode.
This means that there is practically no molecular oxygen at the cathode. Intense oxygen
consumption takes place here and the oxygen partial pressure approaches zero.
The oxygen partial pressure of the medium is present in front of the membrane. This pressure
is approx. 209 hPa in water vapor-saturated air under reference conditions (1013 hPa, 20˚C).
The partial pressure acts as the driving force to transport oxygen molecules through themembrane. The membrane acts as a diffusion barrier, i.e. oxygen molecules permeate themembrane depending on the difference in partial pressure.
In summary, an amperometric oxygen sensor has two important features:
1. The rate of oxygen consumption at the cathode is extremely high. Oxygen permeates themembrane depending on the external oxygen partial pressure (the internal pressure ispractically zero) - the external oxygen partial pressure is the driving force.
2. Due to the diffusion-inhibiting properties of the membrane, the flow of oxygen throughthe membrane and thus the electric signal current subsequently generated is in direct
proportion to the oxygen partial pressure in front of the membrane, i.e. the sensor provides
a linear signal current that depends on the oxygen partial pressure.
The amperometric oxygen sensor is therefore an oxygen partial pressure sensor.

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Oxygen sensors

7.2

Liquistation CSF48

Calibration intervals

7.2.1 Specifying the intervals
The calibration intervals depend heavily on:• The application• The sensor installation position
If you want to calibrate the sensor intermittently for a special application and/or on account ofa special type of installation, you can calculate the intervals using the following method:
Inspect the sensor one month after commissioning for example:
1. Remove the sensor from the medium.
2. Clean the outside of the sensor with a damp cloth.
3. Then dry the sensor diaphragm carefully with a paper towel for example. (onlyamperometric sensors)
4. After 20 minutes, measure the oxygen saturation index in air.
5. Protect the sensor against external influences such as sunlight and wind.
6. Decide whether to calibrate depending on the result:a.

Amperometric sensor:
 If the measured value is not 102 ± 2 %SAT, you must calibrate the sensor.

b.

Optical sensor:
 If the measured value is not 100 ± 2 %SAT, you must calibrate the sensor.

c.

Otherwise extend the period until the next inspection.

4. Proceed as explained in Point 1 after two, four or eight months to determine the optimum
calibration interval for your sensor.
Amperometric sensors only: Make sure to calibrate the sensor at least once a year.

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Oxygen sensors

7.2.2 Monitoring the calibration interval
Once you have established the calibration intervals for your process, you can also have the device
monitor them.
Two functions are available to monitor the calibration interval:
1. Calibration timer (Menu/Setup/Inputs/<Sensor type>/Extended setup/Calib.
settings/Calibration timer) You specify the calibration interval and the controller generates a diagnostics message
once the set time has elapsed.You then recalibrate the sensor or replace it with aprecalibrated sensor.
The timer is reset with the new calibration.
2. Calibration validity (Menu/Setup/Inputs/<Sensor type>/Extended setup/Calib.
settings/Calib. expiration date) You set time limits to specify how long a calibration should be regarded as valid.
Memosens sensors save all the calibration data. In this way it is easy to see whether thelast calibration took place in the specified timeframe and is therefore still valid. This isparticularly advantageous when working with precalibrated sensors.

7.3

Types of calibration

The following types of calibration are possible:• Slope– Air, water vapor-saturated– Air-saturated water– Air, variable– Data entry• Zero point– Single-point calibration in nitrogen or oxygen-free water– Data entry• Sample calibration– Slope– Zero point• Temperature adjustment
Furthermore, the calibration menu for amperometric sensors contains two additional functions
to reset the sensor's internal counters:• Change electrolyte• Change sensorcap

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7.4

Liquistation CSF48

Slope calibration

7.4.1 General principles
In the case of slope calibration, the dependency on partial pressure is used to compare the signal
current to a known, available reference - air.
The composition of dry air is known:• 20.95 % oxygen• 79.05 % nitrogen and other gases
Altitude and partial pressure
The oxygen partial pressure otherwise only depends on the altitude or the current absolute airpressure. At an air pressure of 1013 hPa at sea level, the oxygen partial pressure isapproximately 212 hPa. The absolute pressure and thus also the oxygen partial pressure change
depending on the altitude. Using the barometric formula, the expected oxygen partial pressure
can be calculated with only marginal errors up to a height of several kilometers. As a result,calibration is independent of the altitude.
Three methods for obtaining reliable values for the absolute pressure of air
1. Using the altitude and the barometric formula which provide the correlation between the
expected value for the average absolute air pressure and the altitude (also saved andaccessible in the transmitter or sensor).
2. By measuring the absolute pressure of air with a pressure cell, for example.
3. The relative air pressure reduced to sea level is often available from weather reports. This
relative air pressure can be converted to the absolute value using the barometric formula.
Water vapor
In reality, water in the form of water vapor is also always present in air. This is a contributing
factor to the total pressure. This means that the water vapor in the air changes the oxygen
partial pressure.
However, air can only hold a specific maximum volume of water. The rest is given off ascondensate in liquid form (e.g. drops). The maximum amount of water vapor in air depends on
the temperature and follows known functions.
Air 100% rh
In this calibration model, the percentage of water vapor is deducted on the basis of the altitude
and temperature so that information is available on the oxygen partial pressure actuallypresent. For this model to work correctly, the sensor to be calibrated must be close to a water
surface or be located in the headspace of a vessel partially filled with water. In this way, oxygen
sensors can be precisely calibrated in a wide variety of applications, ranging from power stations
to water treatment.
H2O air-saturated
After an adequate amount of time, water which has been aerated sufficiently is in equilibriumwith the oxygen partial pressure of the air above the water. The "H2O air-saturated" calibration
model uses this property. Here too, the model uses the temperature value to automaticallyreference back to the expected oxygen partial pressures. This model is often used to measureoxygen in closed tanks, such as fermenters filled with water.

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Oxygen sensors

Air variableThis calibration model is for all applications in which the air pressure and air humidity in thevicinity of the sensor do not correspond to the standard atmospheric values previously
mentioned, but are still known. Both variables can be specified here. The model is used, forexample, for installed sensors that should be calibrated in operation at known conditions, suchas in dry rinse air at 1020 hPa.
Sample calibration
Sample calibration is another calibration option. Here, the measured value of the sensor isadjusted to a reference, obtained externally, of the same medium.
7.4.2 Calibration in the media mentioned
The calibration procedure is identical regardless of whether you are calibrating in water
vapor-saturated air, air-saturated water or variable air:
1. Go to the "Oxygen/Oxygen/Slope" menu.
2. Choose between "Air 100% rh", "H2O air-saturated" and "Air variable".
3. Follow the instructions on the display.
4. Accept the calibration data and then return to the measuring mode.
5. Follow the instructions and then press "OK".
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.
7.4.3 Data entry
1. Go to the "CAL/Oxygen/Slope/Data input" menu.
2. Select "New slope" and enter the new value.
3. Then select "OK" when you are asked to accept the calibration data for adjustment.
 The new slope is used.

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7.5

Liquistation CSF48

Calibration of the zero point

7.5.1 General principles
The zero point is not so important when working with relatively high concentrations of oxygen.
This situation changes, however, as soon as oxygen sensors are used in the trace range andcalibration should be performed in the zero point.
Zero point calibrations are demanding as the ambient medium - usually air - already has a highoxygen content. This oxygen must be excluded for the zero point calibration of the sensor andexisting residual oxygen must be eliminated from the sensor environment.
There are two possible ways to do so:
1. Calibration of the zero point in a flow assembly that has been rinsed with gaseous nitrogenof acceptable quality (N5).
2. Calibration in zero solution. An aqueous solution of Na2SO3 depletes oxidizing media andguarantees an oxygen-free environment after an adequate amount of time in airtightconditions.
General rule for zero solutions
A solution of 1g Na2SO3 in 1 l water at approx. 30˚C in a vessel that tapers towards the neck(e.g. Erlenmeyer flask or similar) is free from oxygen after approx. 0.5 h. When sealed airtight,
this state is maintained for around 24 hours. This time is reduced if air is admitted.
Prior to sensor zero point calibration
Has the sensor signal settled and is it steady?
Is the value displayed plausible?
If the oxygen sensor is calibrated too early, this can result in an incorrect zero point. As a generalrule, operate the sensor in a zero solution for 0.5 hours and then assess the signal current in thesteady state.
If the sensor was operated in the trace range before zero point calibration, the time specified
usually suffices. If the sensor was operated in air, far more time must be factored in to drive out
any residual oxygen from the dead volume, which is caused by the vessel design. Here, 2 hours
applies as a general rule.
The zero point can be calibrated as soon as the sensor signal has settled. Here, the current
measured value is calibrated to the zero value.
The reference method (sample calibration in zero point) can also be used here if suitablecollecting vessels or a suitable reference measurement is available.

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Oxygen sensors

7.5.2 Zero point calibration with "zero solution"
Use oxygen-free water for this calibration. What is known as a "zero solution" is available fromEndress+Hauser for oxygen calibration.
As an alternative to the aqueous version, you can also work in an atmosphere that is freefrom oxygen, such as high-purity nitrogen.
1. Go to the "CAL/Oxygen/Zero point" menu.
2. Follow the instructions on the display.
3. Immerse the sensor in oxygen-free water or hold it in nitrogen (not in air!).
4. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.
7.5.3 Zero point calibration via data entry
1. Go to the "CAL/Oxygen/Zero point/Data input" menu.
2. Select "New zeropoint" and enter the new value.
3. Then select "OK" when you are asked to accept the calibration data for adjustment.
 The new zero point is used.

7.6

Sample calibration

Calibration is possible both in the medium and in air. For this purpose, you measure the raw
oxygen value using a reference measurement. You use this reference value to adjust the sensor.
You can either calibrate the slope or the zero point with the reference value.
1. Go to the "CAL/Oxygen/Sample calibration" menu.
2. Choose between "Slope" and "Zero point".
 Use the calibration of the zero point if you want to align the measurement with anothermeasurement. You can correct the sensitivity of your measurement with the slope
calibration.
3. Follow the instructions on the display.
4. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

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7.7

Liquistation CSF48

Resetting the counter

These functions do not adjust the sensor
but reset the sensor's internal counters to "0".
The counter for sensor cap calibrations is used to set warning limits and alarm limits forchanging the membrane cap. This ensures that exhausted membrane caps are replaced intime.
CAL/Oxygen
1. Select the desired function.
2. Follow the instructions.
Change electrolyte• The internal sensor counter for calibrations with the electrolyte used is reset (not visible inthe sensor information).
• Use this function after changing the electrolyte without replacing the membrane cap.
Change sensorcap• The internal sensor counter for calibrations with the membrane cap used is reset. The numberof calibrations performed with the current membrane cap is indicated in the sensor
information.
• Select this function after replacing the membrane cap.

7.8

Temperature adjustment

1. Determine the temperature of your process medium with an alternative measurement, e.g.
a precision thermometer.
2. Go to the "CAL/<Sensor type>/Temperature adjustment" menu.
3. Leave the sensor in the process medium and keep clicking "OK" until temperature
measurement is started via the sensor.
4. Enter the reference temperature from the alternative measurement. You can either enter
the absolute value or an offset for this purpose.
5. Once you have entered your data, click "OK" until the new data have been accepted.
 This completes temperature sensor adjustment.

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7.9

Oxygen sensors

Error messages when performing the calibration

Display message

Causes and possible remedial measures

The calibration is invalid. The range was overrun. Do
you want repeat the last step?

Sensor contaminated or exhausted zero solution. As a result,the permitted limit values for the zero point are exceeded• Clean the sensor• Renew the zero solution• Repeat the calibration

The stability criterion is not fulfilled. Do you want torepeat the last step?

The measured value is not stable. As a result, the stability
criterion is not met.
• Electrolyte and/or membrane cap exhausted, replace• Adjust stability criteria (Menu/Setup/Inputs/Oxygen/Calib.
settings/Stability criteria)

Storage of the data failed. Do you want to retry?

Optical sensor only!
The calibration data could not be stored in the sensor• Check the sensor connection• Repeat the calibration.

Calibration aborted. Please clean sensor before
immersing in process medium. (Hold will be disabled)

Endress+Hauser

The user has aborted the calibration.

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Chlorine sensors

8

Chlorine sensors

8.1

Calibration intervals

Liquistation CSF48

8.1.1 Specifying the intervals
The calibration intervals depend heavily on:• The application• The sensor installation position
You want to calibrate the sensor intermittently for a special application and/or on accountof a special type of installation.
You can calculate the intervals using the following method:
1. Check the sensor:a.

Three months (potable water) or one month (process water) after commissioning
the sensorb.

Using a reference measured value (DPD method) of a medium sample.

3. Compare the sensor measured value to the reference measured value.
4. Depending on your requirements, decide whether the deviation is acceptable or whether thesensor should be recalibrated.
Make sure to calibrate the sensor at least twice a year.
Please note that the DPD method itself is susceptible to high measured errors when themeasured values are very low (< 0.2 mg/l) and can then no longer be regarded as a reliable
method.

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Chlorine sensors

8.1.2 Monitoring the calibration interval
Once you have established the calibration intervals for your process, you can also have the device
monitor them.
Two functions are available to monitor the calibration interval:
1. Calibration timer (Menu/Setup/Inputs/<Sensor type>/Extended setup/Calib.
settings/Calibration timer) You specify the calibration interval and the controller generates a diagnostics message
once the set time has elapsed.You then recalibrate the sensor or replace it with aprecalibrated sensor.
The timer is reset with the new calibration.
2. Calibration validity (Menu/Setup/Inputs/<Sensor type>/Extended setup/Calib.
settings/Calib. expiration date) You set time limits to specify how long a calibration should be regarded as valid.
Memosens sensors save all the calibration data. In this way it is easy to see whether thelast calibration took place in the specified timeframe and is therefore still valid. This isparticularly advantageous when working with precalibrated sensors.

8.2

Polarization

The surface of the working electrode is polarized by the voltage applied by the transmitter
between the cathode and anode. Therefore, after switching on the transmitter when a sensor isconnected, you must wait until the polarization time elapses before starting the calibration.
The sensor requires the following polarization times to obtain a stable display value:
Initial commissioning:
CCS142D-A:
CCS142D-G:
Recommissioning
CCS142D-A:
CCS142D-G:

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60 min.
90 min.
30 min.
45 min.

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8.3

Liquistation CSF48

Types of calibration

The following types of calibration are possible:• Slope– Sample calibration– Data entry• Zero point– Sample calibration– Data entry• Temperature adjustment
Furthermore, the calibration menu contains two additional functions to reset the sensor's
internal counters:• Change electrolyte• Change sensorcap

8.4

Reference measurement

Reference measurement based on the DPD method
To calibrate the measuring system, perform a colorimetric comparison measurement based on
the DPD method. Chlorine and chlorine dioxide react with diethyl-p-phenylenediamine (DPD)
and turn red. The intensity of the red coloration is proportional to the chlorine content.
This red coloration is measured with a photometer (e.g. CCM182) and indicated as the chlorine
content.
Prerequisites
The sensor values are stable (no drift or fluctuating measured values for a period of at least 5min). This is generally achieved by meeting the following requirements:• You waited for the entire polarization time to elapse.
• The flow is allowable and constant.
• Temperature adjustment between the sensor and medium has occurred.
• The pH value is in the permitted range.

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8.5

Chlorine sensors

Slope calibration

8.5.1 Sample calibration
You measure the raw chlorine value using a reference measurement. You use this reference
value to adjust the sensor. You can either calibrate the slope or the zero point with the reference
value.
1. Go to the "CAL/Chlorine menu.
2. Choose between: "Slope" and "Zero point".
 Use the calibration of the zero point if you want to align the measurement with anothermeasurement. You can correct the sensitivity of your measurement with the slope
calibration.
3. Select "Sample calibration" and follow the instructions on the display.
4. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.
8.5.2 Data entry
1. Go to the "CAL/Chlorine" menu.
2. Choose between: "Slope" and "Zero point".
 Use the calibration of the zero point if you want to align the measurement with anothermeasurement. You can correct the sensitivity of your measurement with the slope
calibration.
3. Select "Data input" and enter the new value.
4. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

8.6

Zero point calibration

Zero point calibration is particularly important if measurements are to be compared to one
another, or in the event of measurements near the zero point.
A zero point shift in amperometric sensors is primarily caused by fouling on the cathode. The
special mechanical construction of the sensor with the membrane cap and electrolyte almost
completely eliminates such fouling.

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8.6.1 Sample calibration
You measure the raw chlorine value using a reference measurement. You use this reference
value to adjust the sensor. You can either calibrate the slope or the zero point with the reference
value.
1. Go to the "CAL/Chlorine menu.
2. Choose between: "Slope" and "Zero point".
 Use the calibration of the zero point if you want to align the measurement with anothermeasurement. You can correct the sensitivity of your measurement with the slope
calibration.
3. Select "Sample calibration" and follow the instructions on the display.
4. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.
8.6.2 Zero point calibration via data entry
1. Go to the "CAL/Chlorine" menu.
2. Choose between: "Slope" and "Zero point".
 Use the calibration of the zero point if you want to align the measurement with anothermeasurement. You can correct the sensitivity of your measurement with the slope
calibration.
3. Select "Data input" and enter the new value.
4. Accept the calibration data and then return to the measuring mode.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

8.7

Resetting the counter

These functions do not adjust the sensor
but reset the sensor's internal counters to "0".
The counter for sensor cap calibrations is used to set warning limits and alarm limits forchanging the membrane cap. This ensures that exhausted membrane caps are replaced intime.
CAL/Chlorine
1. Select the desired function.
2. Follow the instructions.

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Chlorine sensors

Change electrolyte• The internal sensor counter for calibrations with the electrolyte used is reset (not visible inthe sensor information).
• Use this function after changing the electrolyte without replacing the membrane cap.
Change sensorcap• The internal sensor counter for calibrations with the membrane cap used is reset. The numberof calibrations performed with the current membrane cap is indicated in the sensor
information.
• Select this function after replacing the membrane cap.

8.8

Temperature adjustment

1. Determine the temperature of your process medium with an alternative measurement, e.g.
a precision thermometer.
2. Go to the "CAL/<Sensor type>/Temperature adjustment" menu.
3. Leave the sensor in the process medium and keep clicking "OK" until temperature
measurement is started via the sensor.
4. Enter the reference temperature from the alternative measurement. You can either enter
the absolute value or an offset for this purpose.
5. Once you have entered your data, click "OK" until the new data have been accepted.
 This completes temperature sensor adjustment.

8.9

Error messages when performing the calibration

Display message

Causes and possible remedial measures

The calibration is invalid. The range was overrun. Do
you want repeat the last step?

Sensor contaminated. As a result, the permitted limit values
for the zero point are exceeded• Clean the sensor• Repeat the calibration

The stability criterion is not fulfilled. Do you want torepeat the last step?

The measured value is not stable. As a result, the stability
criterion is not met.
• Electrolyte and/or membrane cap exhausted, replace• Adjust stability criteria(Menu/Setup/Inputs/Chlorine/Calib. settings/Stability
criteria)

Calibration aborted. Please clean sensor before
immersing in process medium. (Hold will be disabled)

The user has aborted the calibration.

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9

Liquistation CSF48

Ion-selective sensors

Some measured values from other electrodes or sensors are used for measured value
compensation of ion-selective electrodes:• Measured value of temperature sensor for temperature compensation• pH measured value for pH compensation of ammonium (optional)• Potassium or chloride measured value for compensation of interference ions in the case ofammonium or nitrate (optional)
For this reason, there is a sequence for calibration and adjustment that must be followed inorder to achieve a reliable measurement:
1. Temperature adjustment
2. Calibration and adjustment of pH electrode3. Depending on whether compensation electrodes are used:– Calibration and adjustment of ion-selective compensation electrodes (potassium,chloride)– If no compensation electrodes are used:
A correct manual offset is configured for the ammonium and nitrate electrode
4. Calibration and adjustment of ion-selective measuring electrodes (ammonium, nitrate)

9.1

Types of calibration

The following types of calibration are possible:• pH electrode:– Two-point calibration– Single-point calibration• Ion-selective electrodes:– Single-point calibration– Data entry– Two-point calibration– Standard addition ("Expert" only)– Sample calibration ("Expert" only)• ORP sensor:– Single-point calibration• Temperature adjustment by entering a reference value

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9.2

Ion-selective sensors

pH

9.2.1 Two-point calibration
You use calibration buffers to perform two-point calibration. The quality buffers supplied byEndress+Hauser are certified and measured in an accredited laboratory. The accreditation (DAR
registration number "DKD-K-52701") confirms that the actual values and the maximum
deviations are correct and traceable.
1. Go to the "CAL/ISE/CAL/2-pnt. calibration" menu.
2. Follow the instructions on the display.
3. Press "OK" after you have immersed the sensor into the first buffer.
 The system starts calculating the measured value for the first buffer. Once the stability
criterion is met, the measured value is displayed in mV.
4. Continue to follow the instructions.
5. Press "OK" after you have immersed the sensor into the second buffer.
 The system starts calculating the measured value for the buffer. Once the stability
criterion is met, the measured values of the two buffers and the calculated values for theslope and zero point are displayed.
6. Select "OK" when you are asked to accept the calibration data for adjustment.
7. Put the sensor back into the medium and press "OK" again.
 This deactivates the hold and the system starts measuring again.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.
Only use calibration buffers once.
9.2.2 Single-point calibration
1. Go to the "CAL/ISE/1-pnt. calibration" menu.
2. Select the pH electrode and start the calibration.
3. Specify the measured value from the reference measurement.
4. Follow the instructions and immerse the sensor into the buffer.
5. Start the calibration.
6. Select "OK" when you are asked to accept the calibration data for adjustment.
7. Put the sensor back into the medium and press "OK" again.
 This deactivates the hold and the system starts measuring again.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

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Only use calibration buffers once.

9.3

Ammonium, nitrate, potassium, chloride

In the case of potentiometric methods to determine the ion concentration, the voltage from theelectrochemical measuring cell, comprising the ion-selective electrode and a referenceelectrode, is proportional to the logarithm of the concentration (or activity) of the ions underanalysis within the "linear" or "NERNST" range . The calibration parameters slope and zero point
are based on this logarithmic relation, giving these parameters a completely different meaning
here than in other measurement methods.
9.3.1 Single-point calibration
You can calibrate up to 2 ion-selective electrodes simultaneously (not pH/ORP).

‣ Simply select the electrodes to be calibrated from the list.
You use a calibration solution with a known concentration.
1. Go to the "CAL" menu and select the electrode to be calibrated.
2. Select the "1-pnt. calibration" type of calibration.
3. Immerse the sensor into the calibration solution and follow the instructions on the display.
4. Enter the concentration of the calibration solution and follow the instructions.
5. Accept the calibration data and then return to the measuring mode.
 This deactivates the hold and the system starts measuring again.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.
During the calibration, move the sensor in the tank to ensure the necessary flow of medium
to the ion-selective electrode.

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9.3.2 Two-point calibration
Remove the sensor from the medium for calibration.
1. Go to the "CAL" menu and select the electrode to be calibrated.
2. Select the "2-pnt. calibration" type of calibration.
3. Follow the instructions on the display.
4. Press "OK" after you have immersed the sensor into the first calibration solution.
 The sensor starts calculating the measured value. Once the stability criterion is met, themeasured value is displayed.
5. Continue to follow the instructions.
6. Press "OK" after you have immersed the sensor into the second calibration solution.
 The sensor starts calculating the measured value. Once the stability criterion is met, themeasured values of the two calibration solutions and the calculated values for the slope
and zero point are displayed.
7. Select "OK" when you are asked to accept the calibration data for adjustment.
8. Put the sensor back into the medium and press "OK" again.
 This deactivates the hold and the system starts measuring again.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.
During the calibration, move the sensor in the tank to ensure the necessary flow of medium
to the ion-selective electrode.
9.3.3 Data entry
You enter the slope and zero point manually. The calibration function is calculated from thesevalues. Thus, the data entry returns the same result as two-point calibration. You must
determine the slope and zero point in an alternative way.
1. Go to the "CAL" menu and select the electrode to be calibrated.
2. Select the "Data input" type of calibration.
 The slope and zero point are shown on the display.
3. Select each value one after another and then enter your desired numerical value.
 Since you are entering all the variables directly, no additional information is displayedby the controller.
You can cancel the calibration any time by pressing the "ESC" key. No new data are then used toadjust the sensor.

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9.4

Liquistation CSF48

ORP
With this type of calibration, you work with calibration buffers, e.g. ORP buffers fromEndress+Hauser. For this calibration, you remove the sensor from the medium.

1. Go to the "CAL/ISE/Redox/1-pnt. calibration" menu.
2. Follow the instructions on the display.
3. Accept the calibration data and then return to the measuring mode.
 This deactivates the hold and the system starts measuring again.
You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

9.5

Temperature adjustment

1. Determine the temperature of your process medium with an alternative measurement, e.g.
a precision thermometer.
2. Go to the "CAL/<Sensor type>/Temperature adjustment" menu.
3. Leave the sensor in the process medium and keep clicking "OK" until temperature
measurement is started via the sensor.
4. Enter the reference temperature from the alternative measurement. You can either enter
the absolute value or an offset for this purpose.
5. Once you have entered your data, click "OK" until the new data have been accepted.
 This completes temperature sensor adjustment.

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9.6

Ion-selective sensors

Error messages when performing the calibration

Display message

Causes and possible remedial measures

The calibration is invalid. Do you want to start a new
calibration?
Slope out of tolerance.
Zeropoint out of tolerance.
Sample concentration too low.

The calibration buffer is contaminated or the pH value is nolonger within the permitted limits. As a result, the permitted
measured value deviation is exceeded.
• Check the expiry date
• Use a fresh buffer
Incorrect buffers used. As a result, the buffer recognition
function - for example - does not work correctly.
• pH values of the buffers are too close together, e.g. pH 9
and 9.2• Use buffers with a larger pH difference
Sensor aging or contaminated. As a result, the permitted limit
values for the slope and/or zero point are exceeded• Clean the sensor• Adjust the limit values• Regenerate or replace the sensor

The stability criterion is not fulfilled. Do you want torepeat the last step?

The measured value or temperature is not stable. As a result,the stability criterion is not met.
• Keep the temperature constant during calibration• Replace the buffer• Sensor old or contaminated. Clean or regenerate.
• Adjust the stability criteria(Menu/Setup/Inputs/<Electrode slot>/Calib.
settings/Stability criteria)

Calibration aborted. Please clean sensor before
immersing in process medium. (Hold will be disabled)

The user has aborted the calibration.

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Turbidity and solids sensor

10

Liquistation CSF48

Turbidity and solids sensor

The sensor facilitates measurements with different methods adapted to suit the measuring
tasks. The method is specified by selecting the appropriate application and the reference model.
More information on the models and methods available is provided in the Operating
Instructions of the sensor.

10.1 Types of calibration
In addition to the uneditable factory calibration, the sensor stores five other data records. Eachcalibration data record can have up to five calibration points.
• Single-point calibration
This causes a change in the slope. This type of calibration is used if the measured value onlychanges to a limited extent.
• Two-point calibration
This causes a change in the slope and zero point. This type of calibration is used if themeasured value changes to a large extent.
• Multipoint calibration
Calibration at three or more points always causes the measuring curve to be recalculated (zeropoint and slope).
• Temperature adjustment via reference value
Single-point and two-point calibration are based on the data record stored internally in thedevice.
The three-point calibration of the sensor is the standard calibration.
It is absolutely essential:• When commissioning the sensor in sludge applications• When measuring in another type of sludge
Three-point calibration of the sensor is not necessary when recalibrating with the same type ofsludge. Single point calibration suffices here if the levels of turbidity do not differ too much.

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10.2 Turbidity and solids
10.2.1 Factory calibration
The sensor is precalibrated on leaving the factory. As such, it can be used in a wide range ofapplications (e.g. clear water measurement) without the need for additional calibration. The
factory calibration is based on a three-point calibration of a reference sample.
The factory calibration cannot be deleted and can be retrieved at any time. All other calibrations
performed as customized calibrations - are referenced to this factory calibration.
10.2.2 Calibration and adjustment principle
The calibration is always based on a factory calibration saved.
If you use one or two medium concentration values for calibration, the factory data record isrecalculated using these measuring points (non-linear function) and saved as the new data
record. The original factory calibration is not lost.
If you use three or more concentration values for calibration, a completely new calibration
function is calculated that no longer takes the original data record into account.
Give your calibration data records meaningful and useful names. For example, the namecould contain the name of the application on which your data record was originally based.
This makes it easier for you to distinguish between different data records.
10.2.3 Determining the reference value in the laboratory
1. Take a representative sample of the medium.
2. Make sure the sample is as homogeneous as possible.
3. Determine the solids content or the turbidity of the sample with the laboratory method.
4. Use the laboratory measured value as the reference value for calibrating the sensor.
You can also calibrate with samples with added concentrations, or where solid particles
have settled to the base of the tank. In this way, you use a serial dilution to obtaincalibration points that are above and below the expected turbidity or the expected solids
content.

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10.2.4 Calibration and adjustment of the sensor
Use the same medium sample that you used to determine the laboratory measured value.
1. Make sure the sample is as homogeneous as possible.
2. Create the necessary number of calibration samples by diluting the medium sample into
suitable concentrations. For example, you generally obtain very good calibration results witha three-point calibration with concentrations levels of 100 : 33 : 10.

a0006961

Fig. 8: Creating samples for a three-point calibration
A Original sample
B 1 part sample A + 2 parts waterC 1 part sample A + 9 parts water

3. Determine the solids content or the turbidity of the calibration samples in a series ofdecreasing concentrations.
4. Calculate the reference values of your serial dilution from the laboratory measured value
and enter these for every calibration point.

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1.

Sequence of menus during the calibration
a. Menu/Setup/Inputs/Turbidity/Application
Select the application whose saved calibration function is to be changed by additional
measuring points.
b. CAL/Turbidity/Assay
Select a data record for your serial dilution.
c. Dataset name
Assign a name to the data record.
d. Basic application
Select the same application as selected in a.
e. Unit
Decide which unit you want to use. Use the unit in which you also obtained thelaboratory values.

2.

First measuring point (lowest concentration)a. Follow the instructions on the display.
b. Once a stable measured value has been determined, you will be asked for the set point(=laboratory value) of the sample. Enter this set point.

3.

Decide:a. Whether you want to add another value (next highest concentration) to your data
record ("Calibrate next assay") orb. Whether you want to end the calibration and accept the data for adjustment ("Takeover the calibration data?").

4.
5.

Determine all the desired measuring points as explained in Steps 2 and 3.
Completing the calibration and adjustment
a. Once you have determined the last measuring point, accept the data. A message isdisplayed informing you whether the data record is valid.
b. Follow the instructions and then press "OK".
c. You are also asked whether you want to activate the data record just recorded. If you
select "OK", the measured values are calculated on the basis of the new calibration
function.
d. You still have the possibility of editing the data record. Once you have activated thedata record you can only change the set points. It is then no longer possible to delete
measuring points.

You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

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10.2.5 Duplicating data records
This function makes it possible to edit an existing calibration data record, such as the factory
calibration. By entering appropriate data you can then configure an offset for the copied data
record or change the nominal values using a table. This provides a quick and easy way to react
to modified conditions in your process which you are aware of without the need for calibration.
1. Start the function "Duplicate dataset".
2. Select the data record which you want to duplicate.
3. Then select the storage location and give a name to the duplicated record.
 You can only duplicate a record if you have not yet used all the available space for data
records. If no more room is available you must first delete a data record.
4. You can then configure an offset for the new data record or change the nominal values of
the individual calibration points via the "Edit table" function.
5. If you want to use the modified data record, you then have to go to the Setup/Inputs menu
and select the new data record under "Application".

10.3 Temperature adjustment
1. Determine the temperature of your process medium with an alternative measurement, e.g.
a precision thermometer.
2. Go to the "CAL/<Sensor type>/Temperature adjustment" menu.
3. Leave the sensor in the process medium and keep clicking "OK" until temperature
measurement is started via the sensor.
4. Enter the reference temperature from the alternative measurement. You can either enter
the absolute value or an offset for this purpose.
5. Once you have entered your data, click "OK" until the new data have been accepted.
 This completes temperature sensor adjustment.

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10.4 Error messages when performing the calibration
Display message

Causes and possible remedial measures

The stability criterion is not fulfilled. Do you want torepeat the last step?

The measured value or temperature is not stable. As a result,the stability criterion is not met.
• Keep the temperature constant during calibration• Sensor old or contaminated. Clean or regenerate.
• Adjust the stability criteria (Menu/Setup/Inputs<Sensor
type>Calib. settings/Stability criteria)

The calibrated dataset is invalid. Do you want to restart
the calibration?

Calibration point not plausible• Repeat the calibration• Exchange the calibration medium• Sensor fouled --> Clean

Calibration aborted. Please clean sensor before
immersing in process medium. (Hold will be disabled)

The user has aborted the calibration.

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SAC sensor

11

Liquistation CSF48

SAC sensor

11.1 Types of calibration
In addition to the uneditable factory calibration, the sensor stores six other data records. Eachcalibration data record can have up to five calibration points.
• Single-point calibration
This causes a change in the slope. This type of calibration is used if the measured value onlychanges to a limited extent.
• Two-point calibration
This causes a change in the slope and zero point. This type of calibration is used if themeasured value changes to a large extent.
• Multipoint calibration
Calibration at three or more points always causes the measuring curve to be recalculated (zeropoint and slope).
• Temperature adjustment via reference value
Single-point and two-point calibration are based on the data record stored internally in thedevice.

11.2 SAC
11.2.1 Factory calibration
The sensor is precalibrated on leaving the factory. As a nitrate sensor, it can be used in a wide
range of clear water measurements without the need for additional calibration. In the case of a
SAC sensor, it is advantageous to calibrate to the customer's specific process in the majority ofcases. The factory calibration is based on a three-point calibration of a reference sample.
The factory calibration cannot be deleted and can be retrieved at any time. All other calibrations
performed as customized calibrations - are referenced to this factory calibration.
11.2.2 Principle of calibration
The calibration is always based on a factory calibration saved.
If you use one or two medium concentration values for calibration, the factory data record isrecalculated using these measuring points (non-linear function) and saved as the new data
record. The original factory calibration is not lost.
If you use three or more concentration values for calibration, a completely new calibration
function is calculated that no longer takes the original data record into account.
Give your calibration data records meaningful and useful names. For example, the namecould contain the name of the application on which your data record was originally based.
This makes it easier for you to distinguish between different data records.

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11.2.3 Determining the reference values in the laboratory
Different methods are available for the calibration:• Serial dilution of a medium sample• Serial dilution with standard solutions (KHP=potassium hydrogen phthalate)• Combination of both (medium sample with added standard)
1. Take a representative sample of the medium.
 Outlet water, for example, is very suitable for obtaining a representative sample. In thiscase, you do not have to carry out the subsequent step concerning value stabilization.
2. Take suitable measures to ensure that the process of biological and chemical reduction in
the sample does not progress any further.
3. Determine the measured values of your sample array with the laboratory method (e.g. bycolorimetric means using a cuvette test).
11.2.4 Calibration and adjustment of the sensor
To calibrate the sensor, use the same medium sample or sample array that you used todetermine the laboratory measured values. The sample array can also be pure standard
solutions.
Proceed as follows depending on how many measuring points you want to determine for thecalibration:
1. Calibrate the sensor with the first measuring point and enter the laboratory measured value
as the reference value.
2. If you only want to calibrate one point end the calibration by accepting the calibration data.
 Otherwise continue with the next step.
3. Add parent solution to the sample for the 2nd measuring point and determine the measured
value. The reference value is calculated from the laboratory measured value plus the addedconcentration.
4. Repeat Step b as often as needed until you have the desired number of calibration points(max. 5).
To avoid incorrect calibration from carryover:• Always go from a low concentration to a high concentration.
• Clean and dry the sensor after each measurement.
• Make sure to remove medium residue in the sensor gap and in the connection opening for thecompressed air (e.g. by rinsing with the next calibration solution).

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1.

Menu settings for the calibrationa. CAL/SAC/Assay
Select a data record for your serial dilution.
b. Dataset name
Assign a name to the data record.
c. Basic application
Decide which value you want to calibrate: SAC, COD, TOC, DOC or BOD.
d. Unit
Decide which unit you want to use. Use the unit in which you also obtained thelaboratory values.
e. Only for: Basic application = "SAC"
The transmitter can determine the derived variables COD, TOC, DOC and BOD from the
SAC value. Different calculation factors exist for this depending on the reference
method. You can adapt the calculation factor saved at the factory for COD/BOD and
TOC/DOC to your application and also enter an SAC offset.

2.

First measuring point (lowest concentration)a. Start the calibration and follow the instructions on the display.
b. Once a stable measured value has been determined, you will be asked for the set point(=laboratory value) of the sample. Enter this set point.

3.

Decide:a. Whether you want to add another value (next highest concentration) to your data
record ("Calibrate next assay") orb. Whether you want to end the calibration and accept the data for adjustment ("Takeover the calibration data?").

4.
5.

Determine all the desired measuring points as explained in Steps 2 and 3.
Completing the calibration and adjustment
a. Once you have determined the last measuring point, accept the data. A message isdisplayed informing you whether the data record is valid.
b. Select "OK" when you are asked to accept the calibration data for adjustment.
c. You are then asked whether you want to activate the data record just recorded. If you
select "OK", the measured values are calculated on the basis of the new calibration
function.
d. You still have the possibility of editing the data record. Once you have activated thedata record you can only change the set points. It is then no longer possible to delete
measuring points.

You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.

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11.2.5 Duplicating data records
This function makes it possible to edit an existing calibration data record, such as the factory
calibration. By entering appropriate data you can then configure an offset for the copied data
record or change the nominal values using a table. This provides a quick and easy way to react
to modified conditions in your process which you are aware of without the need for calibration.
1. Start the function "Duplicate dataset".
2. Select the data record which you want to duplicate.
3. Then select the storage location and give a name to the duplicated record.
 You can only duplicate a record if you have not yet used all the available space for data
records. If no more room is available you must first delete a data record.
4. You can then configure an offset for the new data record or change the nominal values of
the individual calibration points via the "Edit table" function.
5. If you want to use the modified data record, you then have to go to the Setup/Inputs menu
and select the new data record under "Application".

11.3 Temperature adjustment
1. Determine the temperature of your process medium with an alternative measurement, e.g.
a precision thermometer.
2. Go to the "CAL/<Sensor type>/Temperature adjustment" menu.
3. Leave the sensor in the process medium and keep clicking "OK" until temperature
measurement is started via the sensor.
4. Enter the reference temperature from the alternative measurement. You can either enter
the absolute value or an offset for this purpose.
5. Once you have entered your data, click "OK" until the new data have been accepted.
 This completes temperature sensor adjustment.

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11.4 Error messages when performing the calibration
Display message

Causes and possible remedial measures

The stability criterion is not fulfilled. Do you want torepeat the last step?

The measured value or temperature is not stable. As a result,the stability criterion is not met.
• Keep the temperature constant during calibration• Sensor old or contaminated. Clean or regenerate.
• Adjust the stability criteria (Menu/Setup/Inputs<Sensor
type>Calib. settings/Stability criteria)

The calibrated dataset is invalid. Do you want to restart
the calibration?

Calibration point not plausible• Repeat the calibration• Exchange the calibration medium• Sensor fouled --> Clean

Calibration aborted. Please clean sensor before
immersing in process medium. (Hold will be disabled)

The user has aborted the calibration.

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12

Nitrate sensors

Nitrate sensors

Calibration is performed in the process by comparing the values to an external standard method,by calibrating with standard solutions or by using a combination of both.
• Processes with high nitrate values (> 0.1 mg/l)
Take a sample and determine the nitrate concentration in the laboratory. Then calibrate andadjust the sensor with the laboratory value.
• Processes with very different nitrate values
At time A, take a sample with a high concentration, and measure and calibrate the sample.
At time B - which can be a few days after time A - take a sample with a low concentration,and measure and calibrate the second value.
• Calibration with the addition of standard
If the sludge parameters tend to be constant, you can perform the calibration with a sample
with a low concentration of nitrate and then add standard to the sample.
Take a larger sample (bucket) and analyze some of it by colorimetric means. Calibrate thisvalue in the sensor. Then add standard to the sample, determine the laboratory value andcalibrate the value in the sensor.
Additional calibration points, recalibration
Points can be added to an existing calibration (max. 5 points per data record).
In this way, different media or concentrations can be included in the calibration at different
times.

12.1 Types of calibration
In addition to the uneditable factory calibration, the sensor stores six other data records. Eachcalibration data record can have up to five calibration points.
• Single-point calibration
This causes a change in the slope. This type of calibration is used if the measured value onlychanges to a limited extent.
• Two-point calibration
This causes a change in the slope and zero point. This type of calibration is used if themeasured value changes to a large extent.
• Multipoint calibration
Calibration at three or more points always causes the measuring curve to be recalculated (zeropoint and slope).
• Temperature adjustment via reference value
Single-point and two-point calibration are based on the data record stored internally in thedevice.

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12.2 Nitrate
12.2.1 Factory calibration
The sensor is precalibrated on leaving the factory. As a nitrate sensor, it can be used in a wide
range of clear water measurements without the need for additional calibration. In the case of a
SAC sensor, it is advantageous to calibrate to the customer's specific process in the majority ofcases. The factory calibration is based on a three-point calibration of a reference sample.
The factory calibration cannot be deleted and can be retrieved at any time. All other calibrations- performed as customized calibrations - are referenced to this factory calibration.
12.2.2 Principle of calibration
The calibration is always based on a factory calibration saved.
If you use one or two medium concentration values for calibration, the factory data record isrecalculated using these measuring points (non-linear function) and saved as the new data
record. The original factory calibration is not lost.
If you use three or more concentration values for calibration, a completely new calibration
function is calculated that no longer takes the original data record into account.
Give your calibration data records meaningful and useful names. For example, the namecould contain the name of the application on which your data record was originally based.
This makes it easier for you to distinguish between different data records.
12.2.3 Determining the reference values in the laboratory
1. Take a representative sample of the medium.
 Outlet water is very suitable for obtaining a representative sample. In this case, you do
not have to carry out the subsequent step concerning value stabilization.
2. Take suitable measures to ensure that the process of nitrate reduction in the sample does
not progress any further, such as immediate filtration (0.45 μm) of the sample as per
DIN 38402.
3. Determine the concentration of nitrate in the sample with the laboratory method (e.g.
determining the concentration by colorimetric means using a cuvette test - standard methodin accordance with DIN 38405 Part 9).

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12.2.4 Calibration and adjustment of the sensor
To calibrate the sensor, use the same medium sample or sample array that you used todetermine the laboratory measured values. The sample array can also be pure standard
solutions.
Proceed as follows depending on how many measuring points you want to determine for thecalibration:
1. Calibrate the sensor with the first measuring point and enter the laboratory measured value
as the reference value.
 If you only want to calibrate one point end the calibration by accepting the calibration
data. Otherwise continue with the next step.
2. Add parent solution to the sample for the 2nd measuring point and determine the measured
value. The reference value is calculated from the laboratory measured value plus the addedconcentration.
3. Repeat Step b as often as needed until you have the desired number of calibration points(max. 5).
To avoid incorrect calibration from nitrate carryover:• Always go from a low concentration to a high concentration.
• Clean and dry the sensor after each measurement.
• Make sure to remove medium residue in the sensor gap and in the connection opening for thecompressed air (e.g. by rinsing with the next calibration solution).
1.

Menu settings for the calibrationa. CAL/Nitrate/Assay
Select a data record for your serial dilution.
b. Dataset name
Assign a name to the data record.
c. Unit
Decide which unit you want to use. Use the unit in which you also obtained thelaboratory values.

2.

First measuring point (lowest concentration)a. Follow the instructions on the display.
b. Once a stable measured value has been determined, you will be asked for the set point(=laboratory value) of the sample. Enter this set point.

3.

Decide:a. Whether you want to add another value (next highest concentration) to your data
record ("Calibrate next assay") orb. Whether you want to end the calibration and accept the data for adjustment ("Takeover the calibration data?").

4.

Determine all the desired measuring points as explained in Steps 2 and 3.

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Completing the calibration and adjustment
a. Once you have determined the last measuring point, accept the data. A message isdisplayed informing you whether the data record is valid.
b. Select "OK" when you are asked to accept the calibration data for adjustment.
c. You are then asked whether you want to activate the data record just recorded. If you
select "OK", the measured values are calculated on the basis of the new calibration
function.
d. You still have the possibility of editing the data record. Once you have activated thedata record you can only change the set points. It is then no longer possible to delete
measuring points.

You can cancel the calibration any time by pressing the "ESC" key. No data are then used to adjust
the sensor.
12.2.5 Duplicating data records
This function makes it possible to edit an existing calibration data record, such as the factory
calibration. By entering appropriate data you can then configure an offset for the copied data
record or change the nominal values using a table. This provides a quick and easy way to react
to modified conditions in your process which you are aware of without the need for calibration.
1. Start the function "Duplicate dataset".
2. Select the data record which you want to duplicate.
3. Then select the storage location and give a name to the duplicated record.
 You can only duplicate a record if you have not yet used all the available space for data
records. If no more room is available you must first delete a data record.
4. You can then configure an offset for the new data record or change the nominal values of
the individual calibration points via the "Edit table" function.
5. If you want to use the modified data record, you then have to go to the Setup/Inputs menu
and select the new data record under "Application".

12.3 Temperature adjustment
1. Determine the temperature of your process medium with an alternative measurement, e.g.
a precision thermometer.
2. Go to the "CAL/<Sensor type>/Temperature adjustment" menu.
3. Leave the sensor in the process medium and keep clicking "OK" until temperature
measurement is started via the sensor.
4. Enter the reference temperature from the alternative measurement. You can either enter
the absolute value or an offset for this purpose.
5. Once you have entered your data, click "OK" until the new data have been accepted.
 This completes temperature sensor adjustment.

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12.4 Error messages when performing the calibration
Display message

Causes and possible remedial measures

The stability criterion is not fulfilled. Do you want torepeat the last step?

The measured value or temperature is not stable. As a result,the stability criterion is not met.
• Keep the temperature constant during calibration• Sensor old or contaminated. Clean or regenerate.
• Adjust the stability criteria (Menu/Setup/Inputs<Sensor
type>Calib. settings/Stability criteria)

The calibrated dataset is invalid. Do you want to restart
the calibration?

Calibration point not plausible• Repeat the calibration• Exchange the calibration medium• Sensor fouled --> Clean

Calibration aborted. Please clean sensor before
immersing in process medium. (Hold will be disabled)

The user has aborted the calibration.

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Calibration accessories

13.1 pH calibration buffer
Quality buffers from Endress+Hauser
Solutions which are traced by the DAkkS-accredited Endress+Hauser buffer laboratory (DAkkS= German accreditation body) to primary reference material of the PTB and to standard
reference material of the National Institute of Standards and Technology (NIST) in accordancewith DIN 19266 are used as secondary reference buffer solutions.
pH value
A pH 2.00 (accuracy ± 0.02 pH)
C pH 4.00 (accuracy ± 0.02 pH)
E pH 7.00 (accuracy ± 0.02 pH)
G pH 9.00 (accuracy ± 0.02 pH)I
pH 9.20 (accuracy ± 0.02 pH)
K pH 10.00 (accuracy ± 0.05 pH)
M pH 12.00 (accuracy ± 0.05 pH)
Quantity
01 20 x 18 ml (0.68 fl.oz) only buffer pH 4.00 and 7.00
02 250 ml (8.45 fl.oz)
10 1000 ml (0.26 US gal)
50 5000 ml (1.32 US gal) canister for Topcal S
Certificate
A Buffer analysis certificate
Version
1 Standard
CPY20Complete order code

13.2 ORP buffer
Technical ORP buffer solutions• +220 mV, pH 7, 100 ml (3.4 fl.oz.); Order No. CPY3-0• +468 mV, pH 0.1, 100 ml (3.4 fl.oz.); Order No. CPY3-1

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Calibration accessories

13.3 Conductivity
Calibration solutions
Precision solutions referenced to the NIST standard reference material (SRM) for the qualified
calibration of conductivity measuring systems as per ISO, accuracy ± 0.5 %, with temperaturetable,• CLY 11-A
74.0 μS/cm (reference temperature 25 ˚C), 500 ml
Order No. 50081902• CLY 11-B
149.6 μS/cm (reference temperature 25 ˚C), 500 ml
Order No. 50081903• CLY 11-C
1.406 mS/cm (reference temperature 25 ˚C), 500 ml
Order No. 50081904• CLY 11-D
12.64 mS/cm (reference temperature 25 ˚C), 500 ml
Order No. 50081905• CLY 11-E
107.00 mS/cm (reference temperature 25 ˚C), 500 ml
Order No. 50081906

13.4 Oxygen
13.4.1 Zero solution• 3 screw-cap bottles for producing 3 x 1 liter oxygen-free solution• Order No. 50001041
13.4.2 Calibration vessel
Calibration vessel• for COS61/61D• Order No.: 51518599

13.5 Chlorine
CCM182• Microprocessor-controlled photometer for the determination of chlorine and pH value• Chlorine measuring range: 0.05 - 6 mg/l
• pH value measuring range: 6.5 - 8.4• Order No.: CCM182-0

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13.6 ISE and nitrate

CAY40-

Standard solution
1 Ammonium nitrate, 1 mole
2 Potassium chloride, 1 moleContainer size
A 250 ml (8.45 fl.oz.)
Transport documents
1 Standard documents
2 Incl. dangerous goods sheets
3 Safety data sheet
Certificate
A NoneB Manufacturer's certificate
Complete order code

13.7 Nitrate
Nitrate standard solutions, 1 liter• Standard 5 mg/l NO3 - N; Order No. CAY342-V10C05AAE• Standard 10 mg/l NO3 - N; Order No. CAY342-V10C10AAE• Standard 15 mg/l NO3 - N; Order No. CAY342-V10C15AAE• Standard 20 mg/l NO3 - N; Order No. CAY342-V10C20AAE• Standard 30 mg/l NO3 - N; Order No. CAY342-V10C30AAE• Standard 40 mg/l NO3 - N; Order No. CAY342-V10C40AAE• Standard 50 mg/l NO3 - N; Order No. CAY342-V10C50AAE

13.8 SACKHP standard solution• CAY451-V10C01AAE, 1000 ml parent solution 5 000 mg/l TOC

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Index

A

D

Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Capacitance sensor. . . . . . . . . . . . . . . . . . . . . 8
Air set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Data entry
Chlorine. . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
ORP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Delta slope. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Delta zero point. . . . . . . . . . . . . . . . . . . . . . . . 12
Distribution arm calibration . . . . . . . . . . . . . . . . 5

CCalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Distribution arm . . . . . . . . . . . . . . . . . . . . . . . 5
SAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Sample volume . . . . . . . . . . . . . . . . . . . . . . . . 6
Calibration error
Chlorine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . 28
Nitrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
ORP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Calibration errors
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19, 49
Calibration intervals
Chlorine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Calibration solutions . . . . . . . . . . . . . . . . . . . . 66
Capacitance sensor adjustment . . . . . . . . . . . . . 8
Cell constant . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Chlorine
Calibration error. . . . . . . . . . . . . . . . . . . . . . 43
Calibration intervals. . . . . . . . . . . . . . . . . . . 38
Data entry. . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Polarization . . . . . . . . . . . . . . . . . . . . . . . . . 39
Resetting the counter. . . . . . . . . . . . . . . . . . 42
Sample calibration . . . . . . . . . . . . . . . . . . . . 41
Slope calibration. . . . . . . . . . . . . . . . . . . . . . 41
Temperature adjustment . . . . . . . . . . . . . . . 43
Types of calibration . . . . . . . . . . . . . . . . . . . 40
Zero point calibration. . . . . . . . . . . . . . . . . . 41
Conductivity
Air set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Calibration error. . . . . . . . . . . . . . . . . . . . . . 28
Calibration solutions . . . . . . . . . . . . . . . . . . 67
Cell constant. . . . . . . . . . . . . . . . . . . . . . . . . 23
Installation factor. . . . . . . . . . . . . . . . . . . . . 25
Temperature adjustment . . . . . . . . . . . . . . . 27
Types of calibration . . . . . . . . . . . . . . . . . . . 23

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F
Factory calibration
Nitrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Turbidity and solids . . . . . . . . . . . . . . . . . . 51

I
Installation factor . . . . . . . . . . . . . . . . . . . . . .
ISE
ISE calibration . . . . . . . . . . . . . . . . . . . . . . .
pH calibration . . . . . . . . . . . . . . . . . . . . . . .
Standard solutions . . . . . . . . . . . . . . . . . . .
Types of calibration. . . . . . . . . . . . . . . . . . .

25
46
45
68
44

K
KHP standard . . . . . . . . . . . . . . . . . . . . . . . . . 68

N
Nernst equation . . . . . . . . . . . . . . . . . . . . . . .
NitrateCalibration and adjustment . . . . . . . . . . . .
Calibration error . . . . . . . . . . . . . . . . . . . . .
Factory calibration . . . . . . . . . . . . . . . . . . .
Standard solutions . . . . . . . . . . . . . . . . . . .
Temperature adjustment . . . . . . . . . . . . . .
Types of calibration. . . . . . . . . . . . . . . . . . .

11
63
65
62
68
64
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O
ORP
Calibration buffer . . . . . . . . . . . . . . . . . . . . . 66
Calibration error . . . . . . . . . . . . . . . . . . . . . . 22
Data entry . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Single-point calibration . . . . . . . . . . . . . . . . 20
Temperature adjustment . . . . . . . . . . . . . . . 21
Two-point calibration. . . . . . . . . . . . . . . . . . 21
Types of calibration . . . . . . . . . . . . . . . . . . . 20
OxygenCalibration error . . . . . . . . . . . . . . . . . . . . . . 37
Calibration intervals . . . . . . . . . . . . . . . . . . . 30
Data entry . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Resetting the counter . . . . . . . . . . . . . . . . . . 36
Sample calibration . . . . . . . . . . . . . . . . . . . . 35
Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Slope calibration . . . . . . . . . . . . . . . . . . . . . . 32
Temperature adjustment . . . . . . . . . . . . . . . 36
Types of calibration . . . . . . . . . . . . . . . . . . . 31
Zero point calibration . . . . . . . . . . . . . . . . . . 34
Zero solution. . . . . . . . . . . . . . . . . . . . . . . . . 67

P
pH
Calibration buffer . . . . . . . . . . . . . . . . . . . . . 66
Calibration errors . . . . . . . . . . . . . . . . . 19, 49
Calibration intervals . . . . . . . . . . . . . . . . . . . 14
Data entry . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Sample calibration . . . . . . . . . . . . . . . . . . . . 18
Single-point calibration . . . . . . . . . . . . 17, 46
Temperature adjustment . . . . . . . . . . . 19, 48
Two-point calibration. . . . . . . . . . . . . . . . . . 16
Types of calibration . . . . . . . . . . . . . . . . . . . 15

S
SAC
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Determining the reference values . . . . . . . . 57
KHP standard . . . . . . . . . . . . . . . . . . . . . . . . 68
Principle of calibration . . . . . . . . . . . . . . . . . 56
Temperature adjustment . . . . . . . . . . . . . . . 59
Types of calibration . . . . . . . . . . . . . . . . . . . 56
Sample calibration
Chlorine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Sample volume calibration . . . . . . . . . . . . . . . . . 670Single-point calibration
ORP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17, 46
Slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Oxygen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Slope calibration . . . . . . . . . . . . . . . . . . . . 32, 41

TTemperature adjustment
Chlorine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Conductivity. . . . . . . . . . . . . . . . . . . . . . . . . 27
Nitrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
ORP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Oxygen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19, 48
SAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Turbidity . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Turbidity
Calibration and adjustment . . . . . . . . . . . . 52
Factory calibration . . . . . . . . . . . . . . . . . . . 51
Temperature adjustment . . . . . . . . . . . . . . 54
Types of calibration . . . . . . . . . . . . . . . . . . . 50
Two-point calibration
ORP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Types of calibration
Chlorine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Conductivity. . . . . . . . . . . . . . . . . . . . . . . . . 23
ISE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Nitrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
ORP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Oxygen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
SAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Turbidity and solids. . . . . . . . . . . . . . . . . . . 50

Z
Zero point . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Oxygen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Zero point calibration . . . . . . . . . . . . . . . . 34, 41
Zero solution . . . . . . . . . . . . . . . . . . . . . . . . . . 67

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