Worldwide Inline Process Control Solutions

UV Sensors AF45 / AF46

optek AF46-VB Dual Channel UV Absorption Sensor with Calibration Adapter

Typical Applications:

  • Monitoring of chromatographic columns (i.e., protein concentration)
  • Measuring concentrations of aromatics


Models AF45 and AF46 are high precision UV Absorption sensors for use in the biotech and chemical 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.


A special mercury 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.

The light intensity of the lamp itself is measured by sealed silicon photodiodes using the same filter as the measurement wavelength. The sealed silicon photodiodes also compensate for any variances in lamp intensity, assuring the highest level of precision and long-term performance. Specific lamp design and capability of optek converters operating with lowest photo-currents provide a prolonged life span at the lowest cost of ownership.


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. Different peak wavelengths are available with a variety of bandwidth options ensuring suitable adaption to the application.

While the AF45 uses one wavelength, an AF46 is equipped with an internal beam splitter making it possible to measure two wavelengths simultaneously. Connected to an optek Control 4000 or Control 8000 converter, a wide dynamic range is possible to measure at high and low values with one sensor in one setup. This ensures minimal hold-up volume and installation cost.


NIST-traceable calibration accessories provide absolute measurement confidence.

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Technical Data

AF45 AF46
  1. Sensor Body
  2. Windows
  3. Filter
  4. Measurement detector
  5. Reference detector
  6. Lamp module (mercury)
  1. Sensor Body
  2. Windows
  3. Beam splitter
  4. Filter A
  5. Measurement detector A
  6. Filter B
  7. Measurement detector B
  8. Reference detector A
  9. Reference detector B
  10. Lamp module (mercury)
Measurement principle

1- Channel Absorption of light

2- Channel Absorption of light

Measurement wavelength(s)

254-13, 280-09, 280-13, 290-13, 300-13, 313-13, ... others on request

254-13 / 280-13, 254-13 / 313-13, 280-09 / 300-05, 280-09 / 300-13, 280-09 / 313-13, 280-13 / 300-13, 280-13 / 313-13, 290-13 / 313-13, ... others on request


1 silicon photodiode (hermetically sealed)

2 silicon photodiodes (hermetically sealed)

Reference detector(s)

1 silicon photodiode (hermetically sealed)

2 silicon photodiodes (hermetically sealed)

Measuring Range

any measuring range between

0 - 0.05 to 3 CU

(dependent on filter used / OPL)

(contact product specialist for application specific ranges)

any measuring range between

0 - 0.05 to 2 CU

(dependent on filter used / OPL)

(contact product specialist for application specific ranges)

Optical path length

1 - 160 mm


CU (concentration units) application specific calibration

Light source

low pressure mercury lamp

typical life span: 1 to 2 years (8,000 to 16,000 hours)


< ± 0.05 % of respective measuring range


< ± 0.5 % of respective measuring range


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


all optical parts have an IP rating of IP65 or higher

Sensor Body

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


2-Sapphire, 3-Sapphire Biotech (do not use Pyrex®)

Window gaskets

Viton® (FDA), EPDM (FDA / USP Class VI), Kalrez® 4079, ... others on request (do not use Silicone)

Temperature Ratings
Process temperature

permanent: 0 - 70 °C ( 32 - 158 °F)

peak 15 min/day: 0 - 135 °C ( 32 - 275 °F)

Process temperature

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

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

Process temperature

permanent: -30 - 70 °C (-22 - 158 °F)

peak 15 min/day: -30 - 135 °C (-22 - 275 °F)

Process temperature

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

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



Sensor assembly in ex-proof version accor. ATEX (EN-D)
Approval: DMT 02 ATEX E 175 X
Approval: DMT 02 ATEX E 176 X


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

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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