ENDRESS+HAUSER  OUSAF21-D0C0D1D1D1A1A

Optical sensor for the measurement of low color concentrations

Application

The sensor is used to measure color concentrations in the low measuring range of the visible electromagnetic spectrum.

• Color scale measurement: APHA/Hazen, potassium permanganate in water
• Measurement of color concentration
  • Outgoing goods inspection/purity monitoring
  • Color assurance
  • Discoloration control
  • Distillation monitoring

Your benefits

• As slightest color changes are detected, production quality is guaranteed
  • Measuring range up to 2.5 AU or 50 OD (depending on optical path length)
  • Can be configured to measure color concentration at discrete wavelengths in the visible regionregion
• Outstanding filter properties for highest linearity
• Direct concurrence with laboratory values
• Integrated reference detector for the compensation of particles, bubbles and lamp aging
• Incandescent lamp for long service life and stable measured values

Cost-effective, time-efficient verification (liquid-free)

FM and ATEX approved lamps for applications in the hazardous area

Broad variety of window materials and seals for resistance to a wide range of process media

Optional air purge ports to prevent the formation of condensate on the optical windows

Measuring principle

The measuring principle is based on the Lambert-Beer law.

There is a linear dependency between the absorption of light and the concentration of the absorbing substance:

A = -logA m = ε . c . OPL
A ... absorption, A m ... absorption measured by detector
ε ... Extinction coefficient
c ... Concentration
OPL ... Optical path length

A light source emits radiation through the medium and the incident radiation is measured on the detector side.

A beam splitter splits the light into two beams. One beam is used for measuring while the other acts as a reference to compensate for particles, bubbles and lamp aging.

Once the light has passed through a filter for wavelength selection, the intensity of the light is determined by a photodiode and converted to a photocurrent.

The subsequent conversion to absorbance units (AU, OD) is performed in the associated transmitter.