September 2020

E arly in the pandemic there were claims that compressed air may be a potential source of Coronavirus COVID-19, requiring the installation of sterile air filters (or more frequent filter sterilisations and element changes) to prevent the contamination of food, beverage or pharmaceutical products. At this time, BCAS issued a statement of guidance quoting the World Health Organisation’s (WHO) position that Coronavirus COVID-19 was not an airborne virus. On 9th July 2020 the WHO updated its guidance to include the possibility of airborne transmission of the virus, stating that: “Short-range aerosol transmission, particularly in specific indoor locations, such as crowded and inadequately ventilated spaces over a prolonged period of time with infected persons cannot be ruled out. “However, the detailed investigations of these clusters suggest that droplet and fomite transmission could also explain human-to- human transmission within these clusters. Further, the close contact environments of these clusters may have facilitated transmission from a small number of cases to many other people (e.g., superspreading event), especially if hand hygiene was not performed Process, Controls & Plant Focus on: Compressed Air 20 | Plant & Works Engineering www.pwemag.co.uk September 2020 and masks were not used when physical distancing was not maintained.” BCAS has therefore updated its guidance to include the possibility of airborne/aerosol transmission, but would like to reassure users that this does not impact or change the previously stated advice about the risk and management of Coronavirus in relation to their compressed air system. The simple facts: Compressor rooms are well ventilated. There is minimal risk of short-range aerosol transmission at the point of compressor intake. At the point of compression, the air temperature is high, the heating time is short and with the compression processes, viruses do not tend to survive. During compression, the compressed air temperature is higher than the temperature needed to kill COVID-19. It is documented that heat at 56oC kills the Coronavirus. See WHO information at: https://www.who.int/csr/sars/survival_20 03_05_04/en/ Appropriate downstream purification systems typically treat the compressed air to aerosol sizes significantly smaller than those referenced by the WHO (human generated aerosols <5 micron, good filtration down to <0.01 micron) The compressor has two-stage filtration (panel and intake filter) prior to compression. Air is drawn into an air compressor, through panel filters and then through intake filters on its way to the compression chamber. Ambient air contaminants would have to remain in aerosol form to pass through panel and intake filters in order to enter the compressor intake. This is highly unlikely, but even if panel and intake filtration was compromised, the contaminant would not remain in aerosol form during compression. Best practice guide 102 BPG102 includes guidance on the installation of appropriate inline coalescing filtration and its regular maintenance, as these will remove multiple contaminants include micro-organisms, oil and water aerosols. In addition, the guidance recommends using a dewpoint of -40 oC to inhibit the growth of micro-organisms, and filtration to reduce the micro-organisms and particulate. The specification requires the installation of a minimum of two aerosol reduction filters BCAS reiterates air treatment advice for COVID-19 concerns The British Compressed Air Society (BCAS) is reiterating its advice to compressed air users to adhere to air treatment best practice during the Coronavirus pandemic. PWE reports.

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