Measures H2S in natural gas, fuel gas, biogas or LPG.

The principle of operation is as follows. A reel of paper tape impregnated with lead acetate is exposed to the gaseous process sample in the sample chamber. Hydrogen sulphide (H2S) in the process sample reacts with the lead acetate, after acidification, to form lead sulphide (PbS), a brown compound that stains the tape. The higher the concentration of H2S the darker the stain. A focused LED and single photo detector system continuously measures the darkening stain and the analyser reports this as a 4-20mA output of the concentration of H2S.

Incremental measurements are made on the same spot until saturation occurs, when the tape is advanced to a fresh portion of tape. This reduces tape usage and avoids the need for frequent zero or span calibrations.

The benefits of this technology can be summarised as follows:

As the measurement is specific to H2S, there will be no interference from other sulphur components A continuous analyser with response times as low as 10 seconds The instrument has a wide range capability, measuring between 0-50ppb to 0-100% H2S and a sensitivity of 5ppb H2S The humidifier has a very low volume allowing response times as low as 10 seconds Configuration of the system is via a touch screen which eliminates the need to open the enclosure. Single point calibration results in lower running costs A compact flash card allows for remote evaluation and diagnostics Capital investment is minimised as up to four detection modules can be run from one controller Multi-streaming capability of up to 4 streams per analyser Suitable for gas group IIC environments.

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