In the most recent edition of the online Envriotec editorial, our Siloxane monitors have been featured due to their capabilities to measure Siloxane levels during Biogas production.
How to see the Feature!
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What is a Siloxane Monitor?
The STS Siloxane Monitor uses non-dispersive infrared technology to quantify siloxanes in biogas. Siloxanes are especially challenging to test since they are "sticky" and persistent. One of the challenges of collecting precise measurements is ensuring that the measurement cell and concentrator are not contaminated after each reading. To address this, the monitor is purged with nitrogen to remove any residues, and the concentrator is heated to remove any residue that has not been released, leaving it clean for the next cycle. Under normal conditions, the monitor records one reading per hour: approximately 15 minutes for sampling, 10 minutes for measurement, and the remaining time for cleaning and purging in preparation for the next sample.
The column is then heated, allowing the siloxanes to be released from the media and transported into the measuring cell via an N2 carrier gas. The cell is made up of an infrared source, filters, and a pyroelectric detector that is positioned behind specialised glass. As the carrier gas travels through the cell, the siloxanes absorb the IR signal, lowering the received signal by the detector and resulting in an equivalent voltage drop. This is recorded and processed to generate a mass of material, which, when combined with the sample volume, yields a reading in mg/m3.
The monitor generates a total siloxane reading, which is the sum of all species from L2 to D6. The unit is normally calibrated using either D4 or D5, depending on the site, because these make up 80% or more of the siloxanes detected and are also the most harmful because they are bigger molecules.
View our technical documents for Siloxane monitors here!
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