Introduction

Application and design

The LS4000 is an in situ cross-duct analyzer for measuring

gas component concentrations. It applies the highly selective

optical measuring principle of tunable diode laser (TDL) ab

sorption spectroscopy. The LS4000 is a stand-alone system

and is approved for use in hazardous areas according to

international standards.

The analyzer consists of a transmitter unit with a laser light

source and a receiver unit with a photodetector. Both units are

mounted opposite each other on the process pipe or stack

and are connected by a junction box.

Measurement principle – TDLAS

The LS4000 employs the optical measuring technique of

absorption spectroscopy, which utilizes the fact that a specific

gas absorbs specific light wavelengths.

The light beam is emitted from a tunable laser diode located in

the transmitter unit. The laser light passes through the process

gas and strikes the photodetector in the receiver unit. The

measured gas component present in the optical path absorbs

the laser light, attenuating the light received.

A sophisticated signal algorithm processes the amount of light

attenuation and calculates the gas concentration on the basis

of the Beer-Lambert law. The influence of temperature and

pressure variations is eliminated by dynamic automatic correction.