SO3 Monitor

Measuring and analyzing

How much SO3 do you generate?

In power generation, SO3 measurements provide data to allow the operator to burn fuel in the most efficient way to minimize corrosion of the plant and limit acid discharges to the environment. Monitoring of SO3 is also important where it is formed as a by-product, e.g. in De-NOx systems.

In processes where H2SO4 is used or ore with large amounts of sulphur is processed, the SO3 monitor can measure SO4 2- ions and show emission as mg/Nm³ or ppm.


The Pentol SO3 monitor has been designed to meet a wide range of measuring requirements.
• 1 – 200 ppm SO3
• Flue gas temperature up to 400°C  (up to 550°C with special probes)
• The instrument is portable and suitable for long- and short-term measurements
• The unit is auto-calibrating in a user-defined cycle
• An optional RS232 connector allows to log measurements on a laptop

The Pentol SO3 monitor is based on a wet-chemical process.

The gas sample is measured by means of a heated probe. In the probe head, the sample is cooled down and diluted in a mixture of isopropanol and water. The SO3 condenses and reacts with the sulfuric acid in the liquid phase, eliminating all problems related due to insufficient heating is known from manual measurements.

The sample is then transported to the instrument by the peristaltic pump and reacts with bariumchloranilate, colouring the sample according to the SO3 concentration. The concentration is then measured with a photometer that can be calibrated automatically.

This procedure allows measuring repeatedly and very accurate directly in the plant or in laboratories.

We need to get in touch personally.

Questions regarding function, support, and sales are answered via online chat support and e-mail to, as fast as possible.

Now it´s time for a common test run with a test unit.
Let’s discuss the best individual implementation.

Each power plant is unique

Customer case (considered use)