The technology was developed over a 7 year period following the 2002/3 SARS outbreak, specifically to filter virus particles (virions) in the range 60nm to 180nm without the increase in work of breathing associated with conventional ultra-fine filtration. Designed and engineering in Scotland, the technology then lay idle until the 2019 SARS-COV-2 pandemic, and is now being retooled for manufacture in the UK.
The RD40-AVM filter comprises four layers to provide FFP3 (N99) for PM2.5, with 99.995% efficiency for particulate and virions in the range 60nm to 180nm in a 38mm thick RD40 shell. The filter layers comprise:
- FFP3 certified filtration outer layer.
- Nano-Ag coated FFP3 electrostatic pre-charge layer, which charges particulate to 30 million volts per meter by bringing them within a micron of a 30V +ve source, safe for handling and use. The 30V source is powered by an AAA cell and voltage generator within the filter. Battery is user removable.
- Insulating filter layer, large pores to avoid clogging
- A 7mm thick Nano-Ag coated molecular sieve at -ve potential. The positively charged virions are attracted onto the surface of the negatively charged sieve, for them to be trapped in the molecular cages which are up to 230nm in diameter. A 3nm thick finely dispersed silver coating (Nano-Ag) on the sieve causes the virion to be destroyed after a period of contact.
RD40 module, sealed. Shelf life 7 years when unopened.