AS56-F Color Probe

Single Channel VIS Absorption Probe

AS56-F is a probe for direct installation into pipelines and vessels measuring VIS light absorption of various liquid samples. Optical path length can individually configured to meet the process control requirements.

Used For

  • Color scale:
    • CU (concentration units)
  • Color monitoring
    • of CIP processes
    • for interface detection in beverage production

The AS56-F is a precision absorption probe, which is designed for direct installation into pipelines and provides accurate concentration measurements with remarkable repeatability, linearity and resolution. It is typically used in food and beverage applications to allow cost-effective measurements. The AS56-F uses a specific wavelength of 430 nm in the visible spectrum to measure color in liquids with little or no turbidity. Its lowered power design allows for up to four AS56 series sensors to be multiplexed to one C4000 converter / transmitter.


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

Fast and accurate color measurements
Immediate detection of color changes to verify product quality

Probe design
For pipe and vessel installation
  1. OPL
  2. Windows
  3. Lamp module
  4. Optics modules (incl. filter)
  5. Detector module

No window gaskets used

Measurement principle

1- Channel Absorption of light

Measurement wavelength(s)

AS56-F:430 nm


1 silicon photodiode (hermetically sealed)

Measuring Range


any measuring range between

0 - 0.05 to 1.5 CU

Optical path length

5 or 10 mm


CU (concentration units) application specific calibration

Light source

special incandescent tungsten lamp 5.0 V DC, 450 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

Process Adaption

wetted parts: stainless steel 1.4435 (SS 316L)

surface: N6: Ra < 0,8 μm (32 µinch) - electropolished

housing: stainless steel 1.4571 (SS 316Ti)

Port connection

thread G1-1/4 in., ISO 228/1 for port AS25 (similar Ingold-port)

diameter: 25 mm ( D= 25 H7)

O-ring groove for 30 mm and for 60 mm port length

Port gasket

O-ring 18.64 x 3.53 mm EPDM (FDA / USP Class VI)

Insertion depth

35 mm (1.38 in.) + OPL at a port length of 60 mm (2.36 in.)

Process pressure

0 - 10 bar (0 - 145 psi)


Sapphire (seal-less)

Installation accessories
  • weld-in ports
  • Varivent adapter (50.00)
  • clamp adapter (1.5 and 2.0 in.)
Temperature Ratings
Process temperature

permanent:0 - 90 °C (32 - 194 °F)

peak 60 min/day:0 - 100 °C (32 - 212 °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.

Speed / Spare Parts

Lamp Module AS56

Lamp Module AS56

PN: 1426-3405-1201-01

Installation Kit AS

Installation Kit AS

PN: 1201-3401-0001-00

O-Ring 18.64 x 3,53 EPDM (FDA) (2)

O-Ring 18.64 x 3,53 EPDM (FDA) (2)

PN: 1203-0002-0034-03

O-Ring 4.00 x 1.00 Viton® (4)

O-Ring 4.00 x 1.00 Viton® (4)

PN: 1203-0004-0001-02

O-Ring 50.52 x 1.78 Viton® (4)

O-Ring 50.52 x 1.78 Viton® (4)

PN: 1203-0004-0021-02

x56 Series Product Information

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