Transmissometer

Transmissometer on a runway

A transmissometer is an optical measuring device for determining a dust or gas concentration.

Measuring principle

A beam of light illuminates a measurement volume . The attenuation of the light is a measure of the concentration of dust , gas (using light with a suitable wavelength) or a liquid in the measuring volume. The transmission is measured

${\displaystyle T={\frac {I}{I_{0}}}}$

with = emitted light and = received light. ${\displaystyle I_{0}}$ ${\displaystyle I}$

The transmission can only assume a number between 0 and 1. Where means that no absorption or scattering occurs ( so-called “smoke-free” when measuring dust ). In practice, the transmission is usually given in percent. ${\displaystyle T=1}$

Applications

Transmissometry is mainly used in industrial measurement technology and environmental technology for measuring pollutants in exhaust gases .

• z. B. Emissions measurement in accordance with environmental protection laws (in Germany, e.g. 13/17/23 BImschG or TA-Luft).
• SCHLUMOSED measures the transparency of sewage sludge over time during the separation of wastewater.
• This device is used to measure the visibility range ( RVR ) in air traffic .

literature

• Frank Früngel: A pulse-optical transmissometer for registering the standard visual range between about 40 m and ∞ (videograph) . In: Archives for Meteorology, Geophysics and Bioclimatology, Series B . tape 10 , no. 2 , February 1960, p. 252-263 , doi : 10.1007 / BF02246573 .