Worldwide Inline Process Control Solutions

Turbidity Sensors AF16-N / TF16-N

optek TF16-EX-HT-N Scattered Light Dual Channel Turbidity Sensor

Typical Applications:

  • Separator control, pulp concentration (AF16-N)
  • Filter control, oil in water (TF16-N)

Overview

Models AF16-N and TF16-N are high precision turbidity sensors for use in various industries. The sensors are designed for inline operation and provide accurate concentration measurements with remarkable repeatability, linearity and resolution.

Modular construction of the sensors offers maximum flexibility in adapting to various process needs. Options include electro-polished sensor bodies, hazardous location (explosion-proof) capability, chemical resistant materials (sapphire windows, titanium, Hastelloy, etc.) and high temperature or high pressure versions.

AF16-N (NIR-Absorption / Turbidity)

A special tungsten lamp produces a constant light beam that passes through the process medium. The attenuation of the light intensity, caused by absorption and/or scattering by dissolved and undissolved substances, is detected by a sealed silicon photodiode.

The AF16-N uses light from 730 - 970 nm (NIR) to measure solids concentration independent from color or color changes. Depending on the optical path length, measuring ranges from high percentage (OPL = 1 mm) to 0 - 100 ppm (OPL = 160 mm) are possible.

TF16-N (Scattered Light / Turbidity)

Light scattered from particles (trace suspended solids, undissolved liquids or gas bubbles) in the medium is detected by eight hermetically sealed silicon photodiodes at an angle of 11°. At the same time, the unscattered light is detected by a reference photodiode (comparable to an AF16-N). This unique dual channel design compensates for disturbances of the carrier medium. The sensor can be calibrated in ppm (DE), EBC or FTU and measures extremely low particle sizes and concentrations. Additionally, high particle concentrations can be monitored independent of color at the direct light detector.

OPL

Special optical windows are made from a single crystal sapphire, providing superior resistance to all abrasive and corrosive media. With the appropriate choice of sensor bodies and windows in various lengths, the optimal OPL (optical path length = distance between the windows) can be achieved to meet the measurement requirements, i.e., low/high measuring ranges at highest resolution.

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Technical Data

AF16-N TF16-N
Schematic
  1. Sensor Body
  2. Windows
  3. Filter
  4. Measurement detector
  5. Optics module
  6. Lamp module
  1. Sensor Body
  2. Windows
  3. Focusing optics
  4. Detector 0° (Abs.)
  5. Eight 11° detectors
  6. Optics Module
  7. Lamp module
Measurement
Measurement principle

1- Channel Absorption of light

1- Channel Absorption of light and 2- Channel Scattering of light (11°)

Measurement wavelength(s)

730 nm - 970 nm

Detector(s)

1 silicon photodiode (hermetically sealed)

1 silicon photodiode (hermetically sealed) (Abs.)

8 silicon photodiodes (hermetically sealed) (11°)

Measuring range NIR-Absorption

any measuring range between

  • 0 - 0.05 to 6 CU
  • 0 - 50 to 40,000 ppm (DE)
  • 0 - 20 to 16,000 FTU
  • 0 - 5 to 4,000 EBC

any measuring range between

  • 0 - 0.05 to 5 CU
  • 0 - 50 to 8,000 ppm (DE)
  • 0 - 20 to 3,200 FTU
  • 0 - 5 to 800 EBC
Measuring range Scattered Light (11°) N/A

any measuring range between

  • 0 - 0.5 to 500 ppm (DE)
  • 0 - 0.2 to 200 FTU
  • 0 - 0.05 to 50 EBC
  • (higher (i.e. 100 EBC) with reduced resolution, accuracy)
Optical path length

1 - 1000 mm

40 mm standard (10 - 60 mm with reduced accuracy)

Calibration

Abs.: CU (concentration units) application specific calibration

Abs.: CU (concentration units) application specific calibration basic calibration 11°: in ppm (DE) / FTU / EBC

Light source

special incandescent tungsten lamp 5.0 V DC, 970 mA

typical life span: 3 to 5 years (25,000 to 40,000 hours)

Resolution

< ± 0.05 % of respective measuring range

Repeatability

< ± 0.5 % of respective measuring range (scattered light < ± 0.3 %)

Linearity

< ± 1 % of respective measuring range (specific to application)

Protection

all optical parts have an IP rating of IP65 or higher

Sensor Body
Material

Stainless steel 1.4435 (SS 316L), 1.4539, 1.4571 (SS 316Ti), 1.4462, Titanium 3.7035 (Grade 2), Hastelloy 2.4602 (C22), Plastic TFM4215, PVC, ... others on request

Line size

1/4 in. to 6 in. (DN 6 to DN 150), ... others on request

Process connection

Flanges (ASME, DIN, JIS), Clamps (TC, ISO, DIN), Female Threads (NPT, DIN), Sanitary Threads (DIN 11851), Tube Ends (DIN, ISO, OD), Varivent, ... others on request

Process pressure

10 mbar to 100 bar (0.15 psi to 1450 psi) - higher on request depending on process connection, materials and design

Windows

1-Pyrex®, 2-Sapphire, 3-Sapphire Biotech

Window gaskets

Silicone (FDA), Viton® (FDA), EPDM (FDA / USP Class VI), Kalrez® 4079, ... others on request

Temperature Ratings
Process temperature

permanent: 0 - 120 °C ( 32 - 248 °F)

peak 15 min/day: 0 - 150 °C ( 32 - 302 °F)

Process temperature
OPTION HT

permanent: -30 - 240 °C (-22 - 464 °F)

peak 15 min/day: -30 - 260 °C (-22 - 500 °F)

Process temperature
OPTION EX

permanent: -30 - 120 °C (-22 - 248 °F)

peak 15 min/day: -30 - 150 °C (-22 - 302 °F)

Process temperature
OPTION EX-HT

permanent: -30 - 240 °C (-22 - 464 °F)

peak 15 min/day: -30 - 260 °C (-22 - 500 °F)

Ambient temperature

permanent: 0 - 40 °C ( 32 - 104 °F)

operation: -30 - 40 °C (-22 - 104 °F) with options HT / EX / EX-HT

transport: -20 - 70 °C ( -4 - 158 °F)

Explosion Proof
Ex-proof

none

Ex-proof
OPTION EX (EN-D)

Sensor assembly in ex-proof version accor. ATEX (EN-D) - Approval: DMT ATEX E 176

Ex-proof
OPTION EX (FM-D)

Sensor assembly in ex-proof version accor. FM (FM-D) - Approval: FMG J. I. 3013884

Calibration
Calibration adapter

none

N/A
Calibration adapter VB

Filter adapter FH03 for calibration filter used for sensor verification

N/A
Pressure and temperature ratings specified herein may be subject to limitations - see instruction manual. The appropriate choice of material for all wetted parts is the sole responsibility of the user. Data given are subject to changes without prior notice.

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