Worldwide Inline Process Control Solutions

Color Sensors AF16-F / AF26

optek AF26 Dual Channel Absorption Sensor

Typical Applications:

  • Monitoring of various color scales
    • 0 - 10 to 0 - 500 APHA Hazen
    • 30 to -16 Saybolt
    • 0 - 1 to 0 - 8 ASTM etc.
  • Measuring various concentrations
    • 0 - 100 mg/l chlorine
    • 0 - 5 mg/l iron in hydrochloric acid
    • 0 - 100 % chlorine gas
    • 0-10 ppm to 0-15g/l chlorine dioxide

Overview

Models AF16-F and AF26 are high precision color sensors used to measure color or color changes 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.

VIS-Absorption (Color)

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 sealed silicon photodiodes.

At a specific wavelength in the visible range (385 - 670 nm) there is a loss of light as a result of an increase in color depth. optek sensors measure in various color scales such as Hazen, APHA, ASTM, EBC, Gardner, Saybolt, and many more. Also, many dissolved substances in liquids can be precisely monitored using color measurements. For instance, increasing iron or nickel contents result in a yellow liquid.

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.

Dual Wavelengths

Selected combinations of optical filters make it possible to focus on specific wavelengths ensuring suitable adaption to the application. While the AF16-F uses one wavelength, an AF26 is equipped with an internal beam splitter making it possible to measure two wavelengths simultaneously.

Connected to optek Control 4000 or Control 8000 converters, the second wavelength can be used to compensate for (varying) background turbidity and any lamp intensity variation to assure the highest level of precision and long-term performance. Combined with a long optical path length, even the smallest color changes can be measured.

NIST-traceable

NIST-traceable calibration accessories provide absolute measurement confidence.

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Technical Data

AF16-F AF26
Schematic
  1. Sensor Body
  2. Windows
  3. Filter
  4. Measurement detector
  5. Optics module
  6. Lamp module
  1. Sensor Body
  2. Windows
  3. Beam splitter
  4. Filter A
  5. Measurement detector A
  6. Filter B
  7. Measurement detector B
  8. Optics module
  9. Lamp module
Measurement
Measurement principle

1- Channel Absorption of light

2- Channel Absorption of light

Measurement wavelength(s)

385, 400, 430, 470, 525, 620, 670, 750, 1000 nm, others on request

385/430, 385/550, 385/620, 400/550, 400/620, 420/700, 430/525, 430/620, 430/700, 460/620, 470/620, 470/700, 525/620, 525/700, 550/800, 620/800, 660/750, 670/550, 670/750, 1000/800 nm, others on request

Detector(s)

1 silicon photodiode (hermetically sealed)

2 silicon photodiodes (hermetically sealed)

Measuring Range

any measuring range between

0 - 0.05 to 2.8 CU

(dependent on filter used)

(contact product specialist for application specific ranges)

any measuring range between

0 - 0.05 to 3 CU

(dependent on filter used)

(contact product specialist for application specific ranges)

Optical path length

1 - 1000 mm

Calibration

CU (concentration units) application specific calibration

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

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

Calibration adapter VB

Filter adapter FH03 for calibration filter used for sensor verification

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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