• No results found

Forward, side and back optical scatter design

The diagram below illustrates the basic principles of the forward, side and back scatter optical design. In this design are taken three mea-surements by means of three beam detectors (side, back and forward).

The forward and side beam scatter detection is made in the same way than in the forward and side scatter optical design.

To measure the back scatter exist a special lens. This lens is like if it does not exist when the light beam is emitted from the lamp and it works like a mirror (reflecting the light beam towards the back detector) when the scattered light beam returns.

Using this design are taken three measurements, therefore with the equations of the section 5.5, we calculate three values of the scat-ter numbers, so the turbidity of the sample is obtained with more accuracy.

Figure 9: Back, side and forward scattering design

8 Conclusions and recomendations

Finally, to improve the accuracy of the nephelometric turbidimeter design, the direct, side and back optical scatter design is used because with this design it is possible to obtain three values of the scatter numbers, so the accuracy is better than in the ISI 31 + 223 where is only taken the nephelometric measurement (90 scatter).

In the following lines is explained how can this values of the scatter numbers be obtained.

With the direct, side and back optical scatter design are measured three light intensities from each beam detector (Imf, Ims and Imb):

Imx = I0[8π4NRα2

λ4R2 (1 + cos2θx) + 1 − 3

4(1 − cos θx)

− ln Tc NMd V

4πr3 3

] (27)

By means of the section 5.5 are calculated the scatter numbers due to Mies and Rayleighs theories using two intensity measurements. In this design three intensity measurements are taken thus, three equa-tion systems are arranged. Solving these systems, three scatter num-bers from each theory are found. After that, the average is calculated obtaining a more accurate turbidity value.

Figure 10: Back, side and forward scattering design

From the back and side beam detector are obtained Nmsband Nrsb; from the back and forward beam detector are obtained Nmbf and Nrbf

and from the forward and side beam detector are obtained Nmf s and Nrf s.

Thus, the final scatter numbers is the average of the three mea-surements:

Nmief inal = Nmsb+ Nmbf+ Nmf s

3 (28)

Nrayleighf inal = Nrsb+ Nrbf+ Nrf s

3 (29)

9 References

1. Whipple, G.C & D.D.Jackson 1900. A comparative study of the methods used for the measurment of turbidity of water. Kass.

Inst. Technol. Quart. 13:274

2. Berman. T.P.D. Walline, A. Schneller, J.Rotherberg and D.W.

towsend 1985: Secchi disk depth record a claim for the eastern Mediterranean Limnol. Oceanorg 30:447-448

3. Ross, W.D., J.Paint technology 43(563):51

4. Ricci, Robert W., Mauri A. Ditzler, and Lisa P. Nestor. ”Discov-ering the Beer-Lambert Law.” Journal of Chemical Education 71 (November 1994):983-985.

10 Appendix 1

.

28 Features

• Factory Calibrated Plug and Play Operation

• No Formazine Required for Start-Up

• Measurement Principal to DIN / ISO Standards

• Sapphire Measuring Window

• Optional Cleaning Wiper Blade

• Compact Design

• Enclosure Rating IP67 (NEMA 6) Waterproof

• Distance Between Sensor and Transmitter Up To 200 meters (656 /ft.)

Applications

• Potable Water

• Filter Efficiency and Backwash

• Surface Water Monitoring of Lakes, Rivers and Streams

• Water Recycle and Discharge

• Plant Effluent

• Phase Separation

Description

The Model 31 Turbidity Sensor employs the Nephelometric 90o scattered light method with a measuring frequency in the near-infrared light range of 880 nm according to ISO 7027 / EN 27027. This guarantees a measurement of the turbidity value under standardized,

comparable conditions. Digital filter functions including interference signal suppression and sensor self-monitoring increase measurement reliability. Every sensor in the FNU field of application is carefully factory calibrated using standard procedures. Other customer and substance specific calibration data can be stored.

Specifications

Measuring Ranges 0.000 to 9999 FNU

0.0 to 3000 ppm 0.0 to 3.0 g/l 0.0 to 200%

Wavelength 880 nm

Optical Reference Photodiodes

Factory Calibration Formazine Standard and SiO2

Temperature Sensor NTC

Temperature Rating -5 to 50oC (23 to 122oF)

Pressure Rating 6 bar @ 25oC (87 psi @ 77oF)

1 bar @ 50oC (14.5 psi @ 122oF)

Process Connection 1” Sensor, ¾” FNPT Flow Cell

Enclosure Rating (Waterproof) IP68

Maximum Cable Length 200 meters (656 ft.)

Model 31 Turbidity Sensor

Toll Free: (800) 835-5474 ISI

Telephone: (714) 779-8781 4745 East Bryson Street

.

29

Model 223 Turbidity & Suspended Solids Trasmitter

Toll Free: (800) 835-5474 ISI

Telephone: (714) 779-8781 4745 East Bryson Street

Features

• Measures Turbidity and Suspended Solids in FNU, ppm, g/l, % or %SS

• 96 X 96 mm Panel Mount Enclosure Takes Up Less Panel Space

• Sensors are Factory Calibrated with Formazine Standard and Silicon Dioxide (SiO2)

• “Live Check” Continuously Monitors Sensor Performance

• Up To Four Alarm Contacts Including Temperature

• Dedicated Fault Alarm

• NAMUR Fault Current Alarm

• PID Controller

• 2nd Current Output for Temperature

Applications

• Wastewater & Sewage Treatment Plants

• Surface Water in Ponds, Lakes and Rivers

• Drinking Water

• Effluent Monitoring & Water Recycle

• Filter Breakthrough Monitoring

Description

The Model 223 Turbidity and Suspended Solids Transmitter employs the nephelometric 90o scattered light method with a measuring frequency in the near-infrared light range of 880 nm according to ISO 7027 / EN 27027. The basic transmitter is available with either a 115 VAC or 24 Volt AC/DC power supply, linear isolated current output and one alarm. Features include the addition of a second output for temperature and up to four alarms which may be configured for on-off control functions, alarm limits, timer for cleaning or PID control functions. The TS version adds the diagnostic function Live Check as well as a non-linear programmable current output. Live Check signals an alarm when the sensor signal does not change over a defined period.

Base Transmitter (TU) Plus Package (TS)

Measurement, display and calibration of the process Live Check sensor signal monitoring and alarm.

variable (PV) and temperature.

Isolated current output (Code 0) Programmable non-linear current output.

Temperature output (Code 1) One alarm (Code 05)

On – Off

Dedicated fault alarm (Standard) NAMUR fault current (Standard)

2.4 or 22.0 mA

Code 10 Additional Features

Two Alarm Contacts for PV and Temperature Concentration Measurement in Other Engineering Units

On – Off

Timer for cleaning Automatic Cleaning initiated by an internal alarm or limit

P(ID) Controller violation

Code 16 Additional Features

Four Alarm Contacts for PV and Temperature

On – Off Cleaning initiated externally or automatically by an internal

Timer for cleaning alarm or limit violation

P(ID) Controller

.

30

Model 223 Turbidity & Suspended Solids Trasmitter

Toll Free: (800) 835-5474 ISI

Telephone: (714) 779-8781 4745 East Bryson Street

Specifications

Turbidity Measurement with Sensor Model 31

Measuring Range 0.0 to 9999 FNU, 0.00 to 3000 ppm,

0.0 to 3.0 g/l, 0.0 to 200%

Resolution 0.001 FNU, 0.01 ppm, 0.1 g/l, 0.1%

Repeatability 1.0% of Measured Value (0.02 FNU min.)

Deviation, Output / Input 1.0% of Current Output Range (0.02 FNU min.)

Maximum Cable Length 200 meters

Sensor to Transmitter (656 feet)

Suspended Solids Measurement with Sensor Model 41

Measuring Range 0.0 to 9999 FNU, 0.00 to 9999 ppm,

0.0 to 300 g/l, 0.0 to 200.0%

Resolution 0.01 FNU, 0.01 ppm, 0.1 g/l, 0.1%

Repeatability 1.0% of Measured Value (0.01 FNU min.)

Deviation, Output / Input 1.0% of Current Output Range (0.02 FNU min.)

Maximum Cable Length 200 meters

Sensor to Transmitter (656 feet)

Temperature Measurement

Temperature Sensor NTC 30K @ 25oC (77oF)

Measuring Range -5 to 70oC (23 to 158oF)

Resolution 0.1oC

Repeatability 1.0% of Measuring Range

Digital Inputs 1 and 2

Voltage 10 to 50 V

Power Consumption Maximum 10 mA

Current Output

Range Selectable 0 to 20 mA or 4 to 20 mA

NAMUR Fault Current 2.4 or 22.0 mA

Maximum Load 500 Ohms

Output Scale Expansion 10% to 100%

Output Isolation Max. 350Vrms / 500Vdc

Over Voltage Protection EN 61000-4-5:1995

Auxiliary Voltage Output

Output Voltage 15 V

Output Current Max. 30mA

105

Technical data DRT 15-CE

Light source: bulb, white light Ranges

Portable turbidity meter DRT 15-CE with white light source

The integral rechargeable battery allows use of the DRT 15-CE without mains supply for up to 20 hours. Results are displayed in the measuring ran-ges 0 - 10, 0 - 100 or 0 - 1000 NTU or TE/F units.

The unit uses round vials with a diameter of 28 mm. Operation is by means of a membrane key-pad and a switchover button.

The unit is supplied in a robust, impact-resistant plastic housing.

The total weight is only approx. 2.3 kg.

The housing also contains the sample holder and calibration solution together with the

battery charger as a ready-to-use unit.

The unit has been approved by the US environ-mental authorities for daily turbidity measure-ments as stipulated by the "Primary Drinking Water Regulations" of the "Safe Drinking Water Act". It also meets the requirements of the

"Standard Methods for the Examination of Water and Wastewater" (AWWA/APHA).

Portable turbidity meter MICRO IR

The portable waterproof turbidity meter MICRO IR with infrared light source (860 nm) is designed to measure turbidity over the range 0 to 1100 NTU with a detection limit of 0.01 NTU in accordance with ISO 7027 / DIN/EN 27 027.

The automatic 3-point calibration feature makes unit calibration easy. All the user has to do is press the CAL key and then measure the 3 turbidity standards.

The unit is supplied complete with the turbidity standards (0.02 / 10 / 100 and 1000 NTU) as well as 4 AAA alkaline manganese batteries and a 25 mm test vial.

Lovibond® MICRO IR

Turbidity meter as described above, complete with turbidity standards 0.02, 100 and 1000 NTU, bat-teries and test vial, in carrying case, ready to use Order code: 19 38 00

Accessories

Secondary standards, set of 0.02, 10, 100, 1000 NTU Order code: 19 38 50

Set of 3 empty sample vials, 25 mm ø Order code: 19 38 60

Ambient 0-50 °C

temperature:

Sample volume: 16 ml

Output: analog, 0-1 mA

Full charge op. time: 20 hours Recharge time: 8 hours Power: 6 V, rechargeable Power supply: 220 V / 50 Hz

Lovibond® DRT 15-CE

Turbidity meter white light, complete with turbi-dity standard 0.02 NTU, battery and test vial, in carrying case, ready to use.

Order code: 19 33 70

Accessories

Secondary standards, set of 0.02, 10, 100, 1000 NTU Order code: 19 34 00

Secondary standards, 0.02 NTU Order code: 19 22 40

Set of 3 spare sample vials, 28 mm ø Order code: 19 22 20

Technical data

Principle: nephelometric (90° scattered light) Light source: IR-LED (860 nm) Range: 0-1100 NTU, Auto Range Resolution: 0.01 NTU from 0 - 9.99 Calibration: automatic 3-point-

calibration Response time: 6 - 16 seconds Protection: IP67

Oper. temperature: 0 - 50 °C

Power supply: 4 alkaline-manganese- batteries (AAA) with expected life of over 1000 tests Weight: 0.325 kg with batteries

1.25 kg in case

Model 670

Turbidity Monitor

The Model 670 turbidity monitor is used with a Model TF10 fl ow through sensor to measure low levels of non-dissolved solids, emulsions, or immiscible fl uids in process liquids

• Measures and displays turbidity up to 200ppm or 200 FTU

• One 4-20mA and one 0-10Vdc analog output

• Volt free alarm output contact is suitable for direct connection to a PLC or inclusion in a control scheme

• Lamp fail indication and relay output

• Type 4 DIN plug in unit 3U x 14HP x 160mm deep (2.8”W x 5.1”H x 6.7”D) conserves space and simplifi es mounting

Model 670 Specifi cations

Signal inputs Low level current from Model TF10 forward scatter online turbidity sensor

Range 0.2, 2, 20, 200 FTU or PPM

Accuracy +/- 1% of measurement

range

Linearity +/- 1% of measurement

range

Signal outputs Lamp fail relay contact NO, 0.5A 230Vac resistive load Process alarm relay contact NO/NC, 0.5amp, 230Vac resistive load

4-20mA tracking to range selected, 600 ohm load 0-10Vdc tracking maximum range, 10k ohm load

Power 115, 230Vac, 50-60Hz,

15VA

Operating environment Temperature 0-55°C;

relative humidity 0-90%

Model TF10 Low Turbidity Sensor

Flow through scattered light sensor used with a Model 670 Analyzer for measuring low levels of non-dissolved solids, emulsions and immiscible fluids in process liquids

• Accurately measures low level particulates up to the equivalent of 200ppm SiO

2

using scattered light detection at 11

o

from excitation beam

• Pyrex optics deliver accurate and reproducible performance under harsh industrial conditions.

Quartz and Sapphire optional

• Low voltage incandescent lamp provides long dependable life

• Can be fitted with visible light blocking filters to minimise color related measurement errors

• Wide variety of process connections and line sizes available

• Ultra-hygienic, CIP and SIP resilient flow cell design available with material finish of 16μinch (0.4μm) R

a

• Air purge ports available for preventing condensate buildup on optical windows

• Patented window wiping system option eliminates process buildup on optical windows

• Air purge ports available for preventing condensate buildup on optical windows

• FM and ATEX approved explosion proof lamps for hazardous area applications

• All sensors are pre-tested at the factory and can be supplied with full certification package

Pathlength 40 mm

Wavelength Broadband VIS/NIR or NIR only

Signal output Low level current from high stability silicon photodetectors Process connections Tri-Clamp, ANSI flange, FNPT, DIN flange, dairy fittings.

Others available - contact factory Sensor housing

material 316L, Kynar®, AL6XN®, Hastelloy®, Teflon®, CPVC, PEEK, Nickel, Monel®, Inconel®, Tantalum, Titanium. Others available Sensor housing finish Sanitary 316L sensors - electropolished sensor interior

16μinch (0.4 μmeter) Ra or better. Standard sensors to fine machine finish

O-ring materials EPDM, Viton®, Silicone, Teflon® coated Viton®, Buna, Kalrez®, Specifications

Sensor with optional wiper installed

.

34

Medidor de Turbiedad · Técnica de luz pulsante de 4 haces · Modelo LAT-N1

Descripción:

El Medidor de Turbiedad LAT-N1 de KOBOLD detecta valores medios muy débiles de turbiedad según el estándar Formazin (FTU); EBC también puede ser utilizado. El dispositivo funciona según DIN 38404 / ISO 7027 con la técnica de luz pulsante de 4 haces, por lo que la suciedad de los dispositivos ópticos así como los efectos de la luz de fuentes externas y de la deriva en los componentes electrónicos se compensan confiablemente. La electrónica de evaluación y la adecuación apropiada se combinan para hacer un instrumento robusto y compacto que puede ser instalado fácilmente. La conexión de proceso se ha diseñado según el estándar higiénico para atornillamientos de tubería (DIN 11864). Así los requisitos más rigurosos de higiene son satisfechos. Las entrerroscas hexágonales soldadas y conexiones sanitarias según DIN 11851 están también disponibles.

El rango de medición del dispositivo se puede cambiar manualmente o con una señal digital. Así la exactitud de la medición a través del rango entero de turbiedad de 0,01 - 5 FTU a 0,01-1000 FTU es muy alta.

La señal de salida del 4 20 mA permite conectar diversos dispositivos de evaluación tales como indicadores digitales, reguladores del valor límite o un PLC.

Aplicaciones:

l Control de proceso l Secuencias de dosificación l Elaboración de la cerveza

l Separación de fase en medios levemente turbios l Agua y aguas servidas

Detalles Técnicos:

Método de medición: Luz pulsante de 4-haces según DIN 38404 (90 °C) Rangos de medida

(4-20 mA): 0,01 a 5/10 / 50 / 100 / 500/1000 TE/ F 0,01 a 5/10 / 50 / 100 /250 EBC Precisión de

medición: ± 1% del valor superior del rango Temperatura del

proceso: 0 a 80°C (corto-plazo 120°C) Temperatura

ambiente: 0 a 60°C

Temperatura de

almacenamiento: -20 a +80°C Máxima presión: 6 bar

Material del cuerpo: acero inoxidable 1.4404 (V4A, SS316L)

Material del bloque

óptico: PEEK con cuadros de cristal silica Conexiones del

proceso: DN 40, 50, 65, 80, 100

Conexión sanitaria según DIN 11851 tubo roscado (higiénico) según DIN 11864 mango de adaptación hexagonal (Conforme a EHEDG, 3-A) Longitud de onda: 875 nm

Entrada de control (rango de

sobre interrupcion): 3 x 24 VDC, BCD Salida analógica: 4- 20 mA,

Exceso de corriente limitante <22 mA

Carga: max. 500

Voltaje de

alimentación: 24 VDC, aprox. 100 mA Indicador: LED 7- Segmentos,

4- posición (FTU o EBC) Altura de dígitos: 12,7 mm Tipo de protección: IP 67

Inmunidad al ruido: EN 50082-2 según IEC 801-4, Nivel de Interferencia 3 Emisión de

interferencia: EN 50082-2

Peso: aproximadamente. 3,8 kg

/Ko/10

11 Appendix 2

Now are shown the dependence of the scattered light measured with respect to physical paramenters in Rayleighs expressions. The light beam intensity expressions which are measured by the detectors de-pend of the distance.

11.1 Nomenclature

I0 is the intensity light beam emitted by the lamp source

I1 is the intensity light beam measured by the forward scatter detector I2 is the intensity light beam measured by the side scatter detector I3 is the intensity light beam measured by the back scatter detector I4 is the intensity light beam in the point 4

L1 is the distance between the forward scatter detector and the lamp source

L2 is the distance between the side scatter detector and the direct light beam forming 90

L3 is the distance between the back scatter detector and the direct light beam forming 90

L4 is the distance between the side scatter detector and the lamp source

α is the polarizability α1 is a material coefficient

N is the number of scatters (equivalent to concentration of particles) λ is the wavelength of the light beam

θ is the scattering angle

Figure 11: Dependence of the scattering light with respect of the distance