AF56-N Turbidity Sensor

Single Channel Turbidity Sensor

AF56-N is a high precision sensor for direct installation into pipelines measuring NIR light absorption (turbidity) of various liquid samples. The optical path length can be individually configured to meet the process control requirements.

Used For

  • Turbidity scale:
    • CU (concentration units)
  • Turbidity based
    • phase separation control (beer / milk, milk / water)
    • yeast dosing (brewery)
    • outlet / inlet separator control
  • Lauter tun in brewery

The AF56-N is a precision turbidity detector which is designed for inline operation. Using NIR light from 730-970 nm the AF56-N measures solids concentration independent from color or color changes. Depending on the optical path length (OPL) measuring ranges from g/L to ppm are possible.


Inline turbidity measurement in demanding process conditions
No sampling or by-pass installation needed

Fast turbidity measurement or turbidity changes
Immediate detection of turbidity changes to verify product quality
  1. Sensor Body
  2. Windows
  3. Filter
  4. Measurement detector
  5. Optics module
  6. Lamp module
Measurement principle

1- Channel Absorption of light

Measurement wavelength(s)

AF56-N:730 nm - 970 nm


1 silicon photodiode (hermetically sealed)

Measuring Range

any measuring range between

AF56-N:0 - 0.5 to 4 CU

Optical path length

1 - 200mm


Abs.: 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)


< ± 0.5 % of respective measuring range


< ± 1.0 % of respective measuring range


< ± 2 % 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

1/8 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


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 – 100 °C (32 – 212 °F)

peak (15 min/day):0 – 120 °C (32 – 248 °F)

Process Temperature

permanent:0 – 60 °C (32 – 140 °F)

peak (15 min/day):0 – 80 °C (32 – 176 °F)

Ambient temperature

operation:0 - 40 °C (32 - 104 °F)

transport:-20 - 70 °C ( -4 - 158 °F)

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.

x56 Series Product Information

Visit our documentation page to view a complete list of translated documents.