Fourier Transform Infrared ( FTIR ) Analyzers

Fourier transform infrared (FTIR) analyzers measure the chemical composition of raw materials, intermediate, and final products in a wide variety of process industries. This chapter discusses the basic principles of operation, range of applications, and installation considerations of FTIR. FTIR analyzers are fundamentally based on the same physical measurement principle as nondispersive infrared analyzers. One of the most important characteristics of FTIR analyzers is the range of applications for which they are suited. It is difficult to establish a hard and fast measurement range and accuracy specification for an analyzer technology with such a wide scope of possible applications. The chapter offers simply as a guideline in reviewing the feasibility of using this technology for a specific application. The most important limitation of process FTIR is that the individual concentration data must be mathematically extracted from a single complex spectrum. This imposes two major restrictions: lack of stream knowledge, and stream complexity.