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Turbidez

O que é Turbidez

TURBIDEZ: medida da transparência de uma amostra ou corpo d'água, em termos da redução de penetração da luz, devido à presença de matéria em suspensão ou substâncias coloidais.

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O que é um Turbidímetro?

Turbidímetro mede a capacidade Turbidímetro mede a capacidade que as partículas não dissolvidas que as partículas não dissolvidas tem de dispersar a luz tem de dispersar a luz

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Teoria

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Método Basico de feixe simples

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Medida de Turbidez

Numero de partículas em suspensão Tamanho das partículas em suspensão Cor das partículas em suspensão Forma das partículas em suspensão

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Padrões de dispersão de partículas

Small Particle Medium Particle

Large Particle

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Problemas típicos

Envelhecimento da lâmpada de Tungstênio ou da fonte de luz Fatores de Interferência

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Fatores de interferência

Desvio das características do Sensor Cor da amostra Interferências luminosas

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Padrão de calibração

·

Formazina

Repetibilidade Precisão Estabilidade

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Técnica de diluição

Transferência com Pipeta x Seringa de µl

42 Leitura em FTU 41 40 39 38 1 6 11 16 21 26 31 36 41 46 Numero de Tentativas Pipeta Seringa µl

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Degradação da Formazina

soluções de 1, 10, e 40 NTU

10 1 NTU 10 NTU 1 40 NTU

0.1

0

2

4

6

8

10

12

14

16

18

20

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Horas

UNIDADES

ASBC - "American Society of Brewing Chemists". (American unit used in breweries) EBC - "European Brewery Convention". (European unit used in breweries) FAU - "Formazine Attenuation Units". (Unit used in water treatment for transmitted light measurement (angle 0°) as prescribed by standard) - ISO 7027. FNU - "Formazine Nephelometric Units". (Unit used in water treatment for measurement at 90° as prescribed by standard ISO 7027) FTU - "Formazine Turbidity Unit". (Unit used in water treatment) NTU - "Nephelometric Turbidity Unit". (Unit used i n water treatment for measurement at 90° as prescribed by the U.S. EPA (Environme ntal Protection Agency). TE/F - "Trübungseinheit/Formazin". (German designation, now replaced by the FNU unit)

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Tabela de conversão

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Princípio de Operação do nosso sensor

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X X X X X X X X X X

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Transmissor Transmissor

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Teclas Teclas

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Teclas Teclas

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Teclas Teclas

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Calibração

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OUM 223

Instrument configuration

OUM223E5B.CHP

5.9

Calibration

Possibilities of calibration This function group is used to calibrate the transmitter. Four types of calibration are possible: · Three-point calibration · Adjustment of an existing calibration with the laboratory value · Changes to individual values of the three-point calibration · Installation adjustment · One-point calibration Note:

· If the calibration procedure is

aborted by pressing the PLUS and MINUS keys simultaneously (return to C115, C123, C135, C143 or C153) or if the calibration is faulty, then the previous calibration data are reinstated. A calibration error is indicated by the "ERR" message and flashing of the sensor symbol on the display. In this case, repeat calibration!

· The end of calibration is followed

by a return to the measuring mode. During the hold delay time (field S4), the hold symbol is displayed. Calibration overview The calibration of the measuring chain is a three-point calibration in all cases, i.e. the entire calibration characteristic of the measuring chain for the medium is computed by the OUM 223 transmitter based on three medium samples of known turbidity or known solids concentration. The calibration should be performed in the turbidity or solids concentration range in which you intend to measure. To simplify the three-point calibration, we recommend preparing the three samples required for calibration by dilution of a medium sample. Usually, very good calibration results are obtained with concentrations of 10%, 33% and 100% of the original concentration. The transmitter will propose these concentrations for the three-point calibration. An added advantage of this procedure is that only the turbidity or solids concentration value of the original sample needs to be determined in the laboratory. Note: Especially for samples with very high concentration or very dark coloration, the concentration gradation must be changed. Very good results are achieved with a gradation of 3%, 10% and 100%. Correction of the result after laboratory measurement only requires measurement of the original sample in the laboratory.

Original sample

9 parts zero solution + 1 part orig. sample

2 parts zero solution + 1 part orig. sample

Calibration value 3

Sample 3 Original sample Sample 1 Original sample × 1/10 Sample 2 Original sample × 1/3

UM_3PROB.CDR

Fig. 5.12

Preparation of samples for three-point calibration

39

Instrument configuration

OUM 223

However, this procedure is not a mandatory prerequisite for calibration. You can also take three different samples of the process medium and determine their turbidity or solids concentration values. The following conditions must be met:

· The calibration must be performed in ascending order of concentration. · The measured values of the three samples must differ by at least 10%. · Clean water can be used as the zero solution in the case of elevated solids concentrations.

Note:

· Sludge samples tend to sediment.

It is therefore important to stir the sample well, possibly even during calibration. Do not form a cyclone during stirring, do not stir in a circle.

· If the computed relative calibration

results differ by more than ­50% / +100% from the reference value of 100%, a warning is issued (E084). However, the calibration results can be used.

· The characteristic computed

during the three-point calibration is stored in the currently selected calibration data set (see field B4). If the read-only calibration data set No. 1 is selected, then calibration is not possible.

· If the computed results are outside

the permissible limits, a calibration error is indicated (E045). The calibration is rejected.

Administration of calibration data sets of the transmitter Three calibration data sets can be selected for each application range (FNU, ppm, g/l, %). Of these three data sets (sample characteristics), one is programmed at the factory and cannot be modified (read only). FNU formazine Data set No. 1 (read only) formazine Data set No. 2 (editable) formazine Data set No. 3 (editable) (editable) (editable) SiO2 (read only) kaolin The other two are assigned standard characteristics at the factory which can be adapted by the user (three-point calibration / one-point adaptation / reflection adaptation).

ppm or mg/l SiO2

g/l

%

activated sludge concrete residual water (read only) (read only) activated sludge concrete residual water (editable) (editable) activated sludge concrete residual water (editable) (editable)

Note: The data sets are stored in the sensor, i.e. these data are not lost when the transmitter is replaced. They are automatically read into the transmitter (according to selection).

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OUM 223

Instrument configuration

OUM223E5B.CHP

Version TB: Settings for concrete residual water The versions OUM 223-TB are based on version TS, so they contain the Plus package with additional features. To make commissioning as easy as possible, the instrument is delivered with some settings different from the standard version. These settings ensure that no additional settings are required for applications in concrete residual water. However, if you have made for some reason a set default, then the instrument shows the pristine factory settings. The settings valid for applications in concrete residual water are listed below. Note: If you want to use a voltage output instead of the current output provided by the factory, then you have to connect the enclosed shunt to the transmitter according to the mentioned connections. This will convert the current output to a 0 ... 10 V voltage output.

Settings:

Menu field Operating mode Displayed unit Decimals Measured value damping Calibration data set Current output Characteristic Current range Measured value at 0 mA Measured value at 20 mA Active curve Curve to be edited Table option Number of doublets Doublet number A1 A2 A3 A5 B4 O1 O2 O211 O212 O213 K1 K2 K3 K4 K5 spec. kg/l XX.xx 10 3 Out1 lin 0­20 mA 1.00 1.30 1 1 edit 2 1 ... 2 Setting

Note: Calibration is performed in the % measuring range (the transmitter changes automatically). With the above settings, a density of e.g. 1.12 kg/l = 12% must be selected. In some cases it might be necessary to adjust the calibration to the real sample. For this, a "one-point calibration" is sufficient.

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Instrument configuration

OUM 223

Coding

Field

Selection or range Factory setting

Display

Info

C

Function group CALIBRATION

C

CALIBRAT

3-pt = three-point calibration (1) Corr = three-point correction (2) Edit = edit calibration (3) Refl = adaptation for reflection effects (4) 1-pt = one-point calibration (5) Data = calibration data (6)

C1 (1)

Selection of calibration

3-Pt C1

Calibrat

Only the "Data" function can be accessed for data set 1 (B4). The offset is reset when 3-Pt and Edit is selected.

Immerse sensor in calibration solution (probe 1).

The sensor should be immersed at an adequate distance from the vessel wall (no reflection).

C111

Enter concentration of first calibration solution

last calibration value

100.0 C111

Concentr1

FNU

Immerse sensor in calibration solution (probe 2).

The sensor should be immersed at an adequate distance from the vessel wall (no reflection).

C112

Enter concentration of second calibration solution

last calibration value

330.0 C112

Concentr2

FNU

C112 1.1 × C111

Immerse sensor in calibration solution (probe 3 = original probe).

The sensor should be immersed at an adequate distance from the vessel wall (no reflection).

C113

Enter concentration of third calibration solution

last calibration value

1000.0 C113

Concentr3

FNU

C113 1.1 × C112

Factory settings are printed in bold face; base version does not include functions in italics.

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OUM 223

Instrument configuration

OUM223E5B.CHP

Coding

Field

Selection or range Factory setting

Display

Abortion Warning

Info

Warning Abortion E084 200 % E045

C114

Calibration status is displayed

o.k. E xxx

o.k. C114

Status

E045

E084 50 %

20 %

500 %

C161 ... C163

C115

Store calibration results?

yes no new

yes C115

Store

If C114 = E xxx, then only no or new (exception: calibration warning E 84). If new, then return to C. If yes/no, then return to "Measurement".

C1 (2)

Selection of calibration

3-pt = three-point calibration (1) Corr= three-point correction (2) Edit = edit calibration (3) Refl = adaptation for reflection effects (4) 1-pt = one-point calibration (5) Data = calibration data (6)

Corr C1

Calibrat

C121

Enter correct concentration of third calibration solution

current value from C113 entire meas. range

1000.0 C121

Concentr3

FNU

In case of an unknown probe concentration, but with a definite dilution (1/10; 1/3; 1) the laboratory value is to be entered.

C122

Calibration status is displayed

o.k. E xxx

o.k. C122

Status

If C122 = E xxx, then only no or new (exception: calibration warning E 84). If new, then return to C. If yes/no, then return to "Measurement".

C123

Store calibration results?

yes no new

yes C123

Store

Factory settings are printed in bold face; base version does not include functions in italics.

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Instrument configuration

OUM 223

Coding

Field

Selection or range Factory setting 3-pt = three-point calibration (1) Corr = three-point correction (2) Edit = edit calibration (3) Refl = adaptation for reflection effects (4) 1-pt = one-point calibration (5) Data = calibration data (6)

Display

Info

C1 (3)

Selection of calibration

Edit C1

Calibrat

If the individual samples have been determined subsequently in the laboratory, then you can correct the calibration here.

C131

Enter concentration of first calibration solution

current value from C111 entire meas. range

100.0 C131

Concentr1

FNU

C132

Enter concentration of second calibration solution

current value from C112 C132 1.1 C131

330.0 C132

Concentr2

FNU

C133

Enter concentration of third calibration solution

current value from C113 C133 1.1 C132

1000.0 C133

Concentr3

FNU

C134

Calibration status is displayed

o.k. E xxx

o.k. C134

Status

If C134 = E xxx, then only no or new (exception: calibration warning E 84). If new, then return to C. If yes/no, then return to "Measurement".

C135

Store calibration results?

yes no new

yes C135

Store

C1 (4)

Selection of calibration

3-pt = three-point calibration (1) Corr = three-point correction (2) Edit = edit calibration (3) Refl = adaptation for reflection effects (4) 1-pt = one-point calibration (5) Data = calibration data (6)

Refl C1

Calibrat

Only for solutions 2 FNU / 5 ppm! In very clear media, any effect of backscatter from installation will be eliminated.

Factory settings are printed in bold face; base version does not include functions in italics.

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OUM 223

Instrument configuration

OUM223E5B.CHP

Coding

Field

Selection or range Factory setting 0.0 FNU 0.0 ... 2.0 FNU 0.0 ppm 0.0 ... 5.0 ppm 0.0 mg/l 0.0 ... 5.0 mg/l

Display

Info

C141

Enter correct measured value

0.0 C141

Real PV

FNU

Only for FNU, ppm, mg/l ranges.

C142

Calibration status is displayed

o.k. E xxx

o.k. C142

Status

If C142 = E xxx, then only no or new (exception: calibration warning E 84). If new, then return to C. If yes/no, then return to "Measurement". For FNU: adaptation in C164, C165. For ppm, mg/l: up to 500: adaptation in C164, C165, above 500: adaptation in C166. For g/l, %: adaptation in C166. The basic calibration (three-point) is corrected by the one-point calibration.

C143

Store calibration results?

yes no new

yes C143

Store

C1 (5)

Selection of calibration

3-pt = three-point calibration (1) Corr = three-point correction (2) Edit = edit calibration (3) Refl = adaptation for reflection effects (4) 1-pt = one-point calibration (5) Data = calibration data (6)

1-Pt C1

Calibrat

C151

Enter current calibration value

current meas. value entire meas. range

0.0 C151

Real PV

FNU

C152

Calibration status is displayed

o.k. E xxx

o.k. C152

Status

If C152 = E xxx, then only no or new (exception: calibration warning E 84). If new, then return to C. If yes/no, then return to "Measurement".

C153

Store calibration results?

yes no new

yes C153

Store

Factory settings are printed in bold face; base version does not include functions in italics.

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Instrument configuration

OUM 223

Coding

Field

Selection or range Factory setting 3-pt = three-point calibration (1) Corr = three-point correction (2) Edit = edit calibration (3) Refl = adaptation for reflection effects (4) 1-pt = one-point calibration (5) Data = calibration data (6)

Display

Info

C1 (6)

Selection of calibration

Data C1

Calibrat

C161

Calibration point 1 is displayed

reference value

101.4 C161

Concentr1

%

Deviation relative to standard sensor (100 %).

C162

Calibration point 2 is displayed

reference value

99.3 C162

Concentr2

%

Deviation relative to standard sensor (100 %).

C163

Calibration point 3 is displayed

reference value

98.7 C163

Concentr3

%

Deviation relative to standard sensor (100 %).

C164

Slope 1 is displayed

current value

230 C164

Slope 1

Slope of sensor characteristic 1

C165

Slope 2 is displayed

current value

375 C165

Slope 2

Slope of sensor characteristic 2

C166

Conversion factor is displayed

current value

1 C166

ConvFact

Conversion factor from internal turbidity units to displayed unit.

Factory settings are printed in bold face; base version does not include functions in italics.

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OUM 223

Instrument configuration

OUM223E5B.CHP

5.10

Offset

Meas. value Calibrated value

The settings in the OFFSET function group can be used to calibrate the measurement to a reference measurement. This requires a linear shift of all values measured, i.e. the adjustment is determined for one measured value, and all others are calculated using the same offset.

Current meas. value

Time t

OFFSET.CDR

Fig. 5.13

Offset

Coding

Field

Selection or range Factory setting

Display

Info

V

Function group OFFSET

V

OFFSET

V1

Enter absolute value

current meas. value

0.0 V1

Real PV

FNU

V2

Enter offset

current offset

0.0 V2

FNU

PV Offset

V3

Calibration status is displayed

o.k. E xxx

o.k. V3

Status

If the calibration status is not okay, then the second display line shows an explanation of the error. If V3 = E xxx, then only no or new. If new, then return to V. If yes/no, then return to "Measurement".

V4

Store offset?

yes no new

yes V4

Store

Factory settings are printed in bold face; base version does not include functions in italics.

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Information

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