Corrosion from air: monitoring air quality for the gases that do the damage

The sulphur-based gases sulphur dioxide (SO₂) and hydrogen sulphide (H₂S) are known for the impact they can have on metals. AQMesh monitors either or both, from waste processing sites to data centres and volcanic regions.

Two AQMesh pods were installed on a UK wastewater site to measure continuous real-time H₂S levels, as the containers housing engines were corroding very quickly. The two pods were mounted in different locations and recorded significant levels of H₂S. Peaks of over 400ppb (0.4ppm) were seen in one location, but the high sensitivity of this sensor shows real-time changes at single ppb levels. Readings are typically 15-minute averages, but can be as short as 1-minute, with user-settable alerts available, normally triggered when H₂S - or another chosen pollutant - exceeds a set level.

Other applications suffer from high sulphur levels in the air, including landfill, processes which generate biogas - such as palm oil processing - and of course the oil and gas industry, particularly where sour gas is involved. Paper processing and the fertiliser industry also produce oxides of nitrogen (NO_x) and sulphur, with one fertiliser plant in Australia using AQMesh to monitor SO₂ alongside NO_x and ozone (O₃).

Another customer in Australia was concerned about the corrosive effects of SO₂ from a nearby mining operation and used AQMesh to compare SO₂ readings against the corrosion of ‘sacrificial’ metal squares placed on equipment and street furniture.

H₂S has a foul and unpleasant odour, which can draw complaints from communities that are near to any facility that is producing it, such as landfill sites. AQMesh is currently installed at several landfill sites in the UK, measuring H₂S, total volatile organic compounds (TVOC), carbon dioxide (CO₂) and methane (CH₄) near their operations and along the site boundaries. Similarly, in the USA, San Diego County Air Pollution Control District (SDAPCD) is using AQMesh to monitor H₂S and other pollutants due to toxic waste flowing into the Tijuana River Valley from unregulated wastewater and landfill sites on the Mexican side of the border.

Data centres are also known to be at risk from sulphur in the air. As the largest data centre operators expand into new territories, the local air quality can be different to what they are used to. Whilst back-up generators may cause low levels of sulphur emissions (depending on the fuel used), some industrial areas have consistently or regularly high levels of H₂S or SO₂. The sensitive copper components that are critical to reliable data management can be affected by airborne sulphur, causing 'dendrite whiskers' which cause shorting of components and data errors. Continuous monitoring of the air entering data centre ventilation systems allows the risk to be monitored and managed.

AQMesh was also used in Nicaragua to monitor around volcanic areas, and then around similarly active areas in Iceland. Whilst high levels of SO₂ were expected in Nicaragua - that was the point of the project - it was interesting to see what impact what was effectively was airborne sulphuric acid had on the AQMesh pod itself. Although some of the additional security fittings used locally were corroded, the pod coped very well with the harsh conditions.

SO₂ and H₂S are just two of many measurements that AQMesh pods can be configured to monitor. A single AQMesh system can measure up to 6 gases out of NO, NO₂, O₃, CO, SO₂, H₂S, TVOC and CO₂, as well as PM, noise and an optional ultrasonic wind speed and direction sensor. Autonomous power can be supplied with the AQMesh smart solar pack and there is a variety of data access options to suit all needs. With wireless communications and remote support, pods can be easily installed anywhere, by anyone.

Contact our experienced team today to find out more about AQMesh and how it can support your industrial monitoring requirements.