ASD25-N Absorption Probe

Single Channel Absorption Probe

ASD25-N probe for direct installation into bioreactors, pipelines and vessels measuring absorption, cell growth and optical density of various liquid samples under sanitary process environments. The probe is suited for Sterilization In Place (SIP) / and Clean In Place (CIP) procedures.

Used For

  • Turbidity (optical density) scale:
    • CU (concentration units)
  • Absorption based monitoring of:
    • cell growth and bacterial fermentation (Biotech, Pharma)
    • algae concentration (Biotech, Pharma, food)

The ASD25-N absorption probe is designed for use in production scale fermenters or bioreactors to precisely measure the growth of microbial or cell cultures as a function of NIR absorption. The extremely durable probe is designed for sanitary bioprocess environments and can be used in CIP / SIP processes.


LED light source for slim sensor design
Fits into standard Ingold & safety ports

Various optical path lengths (OPL) are available:1 , 5, 10 and 20 mm
Optimal sensors for any OD range

CIP/SIP optimized design (3A)
Maximized process safety, minimized contamination risk
  1. OPL
  2. Sapphire windows
  3. Detector
  4. Daylight filter
  5. LED light source

No window gaskets used

Measurement principle

1- Channel Absorption of light

Measurement wavelength(s)

840 - 910 nm


1 silicon photodiode (hermetically sealed)

Measuring Range

any measuring range between:

  • 0 - 0.05 to 4 CU
Optical path length

1, 5, 10 or 20 mm

Light source

Hybrid LED (hermetically sealed), 5.4 V DC, 100 mA

typical life span: approx 10 years



Process Adaption

wetted parts: stainless steel 1.4435 (SS 316L) dF < 1 %, BN2

surface: N5: Ra < 0,4 μm (16 µinch) - electropolished

Port connection

OSP25-GS60 (similar Ingold-port)

nominal length:60 and 30 mm

diameter:25 mm

thread:G1-1/4 in. ISO 228/1

Port gasket

O-ring 18.64 x 3.53 mm EPDM (FDA / USP Class VI), others on request

Insertion depth

35 mm + OPL with port length 60 mm

Process pressure

0 - 10 bar

(0 - 145 psi)


Sapphire (seal-less)

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

permanent:5 - 65°C (41 - 149°F)

peak (60 min./day):5 - 135 °C (41 - 275 °F)

thermal shutdown at approximately 75 °C (167 °F)

Ambient temperature

operation:0 - 40 °C (32 - 104 °F)

transport:-20 - 70 °C ( -4 - 158 °F)

Sterilization conditions

Autoclaving not possible

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.

Sorry no spare parts listed yet. Please contact your local representative for support.

C4000 - C8000 Product Information

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