Measurement and Testing
How is Ammonia Monitored?
Jun 09 2021
From minimising air pollution to protecting employees, ammonia monitoring is fundamental to human and environmental health. The sharp and sour smell can be detected by the nose at concentrations as low as 0.04 parts per million (ppm), with exposure to concentrations higher than 300 ppm posing an immediate threat to health and life.
Sophisticated instruments are used to monitor ammonia, many equipped with the technology to detect both trace levels and life-threatening leaks. Read on to find out more about some of the advanced monitoring methods used today, including chemiluminescence, photoacoustic spectroscopy and laser-based analysers.
Photo Acoustic Spectroscopy (PAS)
Electromagnetic radiation absorption levels and acoustic pressure waves are used to detect trace levels of ammonia.
Simple and reliable, Electrochemical (EC) sensors rely on a chemical reaction to detect ammonia. The reaction creates a low-voltage current, with the intensity used to measure NH3 concentration.
Useful for monitoring atmospheric ammonia, Chemiluminescence is a form of light-based technology used to detect NH3. The technique uses a thermally stabilised photodiode to measure the intensity of light produced by an ammonia-fuelled chemical reaction.
Fourier Transform Infrared Spectroscopy (FTIR)
FTIR analysers use wavelength variations to detect NH3 and determine concentrations.
Dry Colorimetric Method
Dry Colorimetric detectors use an impinger to collect gas and convert it into a liquid. The addition of chemical reagents triggers a colour change, which reveals how much ammonia is present in the sample.
Tuneable Diode Laser Absorption (TDLA)
Accurate and reliable, Tuneable Diode Laser Absorption directs a beam of near-infrared (NIR) light onto a sample cell. A mirror then reflects the NIR back to a solid state detector, which measures concentration levels according to light intensity.
Portable Gas Detection
Handheld portable gas detectors offer the scope to detect and measure atmospheric ammonia in the palm of the hand. They’re especially useful in the mining and manufacturing sectors, where employees are at higher risk of exposure to ammonia.
Active Diffusion Denuder
The Active Diffusion Denuder method is used across the UK to map spatial and temporal ammonia emissions.
Adapted Low-Cost Passive High-Absorption (ALPHA)
Adapted Low-Cost Passive High-Absorption (ALPHA) air samplers detects and measures atmospheric ammonia concentrations. They’re championed by environmental monitoring bodies like the UK Centre for Ecology & Hydrology (UKCEH).
Over the past decade, laser-based analysers have set a new benchmark for ammonia monitoring. Precise, accurate and highly sensitive, the advanced instruments can detect extremely low trace levels of ammonia. This makes them ideal for use in the emissions monitoring sector, as well as in manufacturing plants and laboratories where ammonia exposure is a major health and safety risk. Find out more in ‘New perspectives in ammonia monitoring.’
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