Total Sulfur Measurement and Analyzers
Total sulfur measurement in gas and petroleum product streams: UV fluorescence, tape-based and chromatographic analyzers, ATEX-cabinet process analysis systems.
Measurement methods: UV Fluorescence, Gas Chromatography, Tape-Based Measurement
What is total sulfur and why is it measured?
Total sulfur is the sum, expressed as sulfur, of all H₂S, mercaptans, sulfides and other sulfur compounds present in a gas or liquid stream. In refineries, the sulfur content of fuel products is governed by quality specifications; sulfur in natural gas and process gases determines catalyst life, corrosion and emissions. Because catalysts can be poisoned at very low sulfur levels, continuous monitoring of total sulfur in the feed is important.
Where is total sulfur measured?
- Refinery product streams: Quality control on diesel, gasoline and naphtha lines.
- Gas processing: In natural gas, fuel gas and post-amine gas streams.
- Sulfur recovery and flare lines: Pre- and post-combustion control.
- Geothermal and biogas: Tracking total sulfur together with H₂S.
Methods for measuring total sulfur
The most common online method is UV fluorescence: the sample is burned in a high-temperature furnace, converting sulfur to SO₂, which is measured by fluorescence; it can be applied to liquid and gas samples. Tape-based analyzers determine total sulfur together with H₂S from the color change on a chemically impregnated tape. Gas chromatography separates sulfur compounds on a column and measures them individually with sulfur-selective detectors such as FPD, showing which compound is dominant.
Choosing a total sulfur analyzer
- Sample phase (gas/liquid) and expected sulfur range
- Sampling and conditioning: heated line, filter, fast-loop
- Hazardous area classification
- Consumables and maintenance interval
Total sulfur measurement with Tetra
Tetra supplies analyzers such as Thermo Scientific SOLA iQ, PAC NSure, Galvanic ProTech 903 and Yokogawa GC8000, and delivers them as complete analysis systems with ATEX-compliant cabinets, sample preparation and fast-loop systems. Installation, commissioning, calibration and spare parts support are provided in Türkiye by Tetra.
Frequently asked questions
What unit is total sulfur expressed in?
In liquid petroleum products, total sulfur is generally given in mg/kg by mass (ppm by weight), and in gas streams in ppm by volume or mg/Nm³. The European diesel fuel standard EN 590 sets a maximum limit of 10 mg/kg for sulfur content. Product specifications at this level require online analyzers to measure stably in the low ppm range.
What is the difference between an online total sulfur analyzer and laboratory analysis?
In the laboratory, total sulfur is mostly measured at set intervals on collected samples, using UV fluorescence methods such as ASTM D5453. An online analyzer applies the same principle continuously on the process line and shows immediately when product goes off-specification, providing fast data for blending and unit control. Regularly comparing online results with laboratory results confirms measurement reliability.
When is gas chromatography preferred for total sulfur measurement?
Gas chromatography is used when compounds such as H₂S, mercaptans and sulfides need to be known individually, not just the total value. This information matters, for example, when tracking natural gas odorant or identifying the compound poisoning a catalyst. Because a GC cycle takes on the order of minutes, it can also be used together with UV fluorescence analyzers in control applications that need a fast response.
Why is sampling critical in a total sulfur analyzer?
Sulfur compounds, especially at low concentrations, can adhere to line surfaces and cause measurement lag or loss, so inert-coated tubing and a suitable line temperature are used. A fast-loop arrangement ensures that fresh sample reaches the analyzer quickly. For liquid samples, the repeatability of the vaporization and dosing step is decisive for measurement stability.
Products measuring this parameter
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