System for measuring a number of different samples with a single photometer.
If a given installation has a number of samples with similar properties requiring measurement, switching between samples can provide an economical solution. Each sample is drawn continuously, and then passed through a three-way control valve that either discards it or sends it to the photometer. An electronic control system opens the photometer inlet cyclically in accordance with a programmed sequence. The instrument stores the individual readings and provides outputs (0/4..20 mA) set permanently for each of the sample flows.
The continuous circulation of samples ensures an immediate supply of new sample substance to the photometer upon switching, and also prevents solids from building up in the sampletaking lines.