Since the outbreak of the Coronavirus (COVID-19) we have been asked the question; can we upgrade our filters to reduce the risk of Coronavirus infection spreading through our air-conditioning system?
The virus itself is very small, in the range of 0.01 and 0.1 microns and as such will not be stopped by regular ventilation air filters. SPCB UK can supply ULPA and HEPA filters which will stop the virus, but these are best used for applications where the infection is being controlled or investigated such as hospitals, public health laboratories and similar environments. In these cases it is likely that the end user will want a “safe change” filters system, also known as bag-in-bag-out.
In most cases it is simply not possible to easily upgrade existing ventilation systems to accept HEPA or ULPA filters.
This is because ventilation systems are designed and installed as a whole and the air resistance generated by a HEPA or ULPA filter is large by some magnitudes than regular filters. Typically HEPA filters are considerably deeper than regular panel filters. In addition to achieve HEPA or ULPA filtration requires the filter framing system to be much more airtight than regular systems.
However there are actions we can carry out which might help to reduce infection spreading.
It is possible to upgrade existing systems quite easily to panels filters or bag filters rated ePM1 >80%.
We are still finding out new information about Coronavirus, however the latest information is that the virus itself is not airborne. It needs to grab a ride on either water droplets (coughs and sneezes) or on particulate matter PM’s. It is the case that particulate matter in the range of ePM1 and ePM2.5 will go right through coarse filters (G1-G4 to the old EN779 standard), but will on the whole be stopped by a decent ePM1 >80% filter (in old terms F8/F9).
The danger is that many heating and ventilation systems rely heavily on recirculating air, and as has been shown on cruise ships and other closed environments this will potentially allow the virus to spread from room to room.
When upgrading a filter system it is likely that the clean pressure drop will be higher than the previous filters, however this is to be expected as the filters are stopping smaller particles.
See the attached PDF for more details here - Covid19 Spcb