Continuing our discussion about virus vs. air filters, Sean O'Reilly, AAF Flanders, provided us with a brief about the effectiveness of the AAF Flanders Filters at reducing airborne Coronaviruses.
Check it out!
Q&A Report – Webinar
Slide 14 of Bob's presentation, what is the virus size associated with these numbers?
For Kathleen, I have seen filters discharge in less than 3 weeks. All depends on the environment and the contaminants in the air.
The studies I have seen were based on putting air filters into buildings and pulling them out on a schedule. There was definitely drop by 2 weeks but more occurred after that. But no data in between times that the filters were being exposed.
Some HVAC filter manufacturers do not have MERV rating, such as 3M, how does a consumer know the filtration rating?
Good Question! There are a few “comparison tables” out there that make conversion estimates. Aside from actually obtaining an actual ASHARE 52.2 test, there is not a defendable way to make the comparison. This is problematic of course and, to address this the CEC in California has required MERV data to be printed on the filter - regardless of who actually markets or sells the filter. Perhaps that logic can be applied nationwide?
Do we see a synergy between electronic and media-based filters, a hybrid option with benefits of both!
There are so many types and possible configuration that there is no one answer. I would suggest that the answer to this is certainly “YES”. There is a synergy - but it may not be a positive one. It is clear to us that a Hybrid design has great potential! great point!
What would be the best way to create anti-viral capability in a retrofit design considering the system can’t handle the high-pressure drop of MERV 13? Will you recommend an electronic class with MERV ratings?
This is a tricky answer as electronic air cleaners can't currently get MERV. ASHRAE currently recommends adding UVC or room air cleaners to get more air cleaning. Use the highest MERV the HVAC system can accommodate - possibly MERV 11. Then consider adding UV.
For medium risk, will MERV 11 + UVC will work?
My opinion is yes if the UVC is well-designed for HVAC use (not designed just for coil cleanup)
Yes, the idea is to reduce risk. MERV 11 is definitely better than MERV 8. Also, consider HEPA Air Purifier to reduce risk further I would suggest that you never assume that the filter technologies are the end of your effort in creating good IAQ. Always consider the holistic impacts too - air change rates, duty cycle on the system, outside contaminations, in room sources, etc. You can’t make a good decision considering ALL these aspects!
Another good question Himanshu! - the BFE and VFE aspect in face mask testing is specific to medical masks (not respirators intended for nonmedical applications). Most of the HVAC filter test protocols do NOT address issues outside the HVAC arena. So I would assume that is why you do not see them applied there.
For Mr. Luukkonen: Is Spunlace better than hydroentangled as a barrier?
Is there any ASTM or any other test standard that we can carry out for air filter for BEE/VEE efficiency and kill rate test on the filter surface?
Will the participants have access to this presentation?
Yes! The PPT will be ready for download and we will send link sometime today :)
What type of filter media is used in PAPR equipment?
Typically HEPA filter.
Agreed with BOB but the challenge is VRF systems have bought energy efficiency but there have several limitations of ventilation especially in Asian markets!
Agreed. ASHRAE is working on a new assessment protocol that will likely mix performance criteria (one number to evaluate filters for energy use as well as filtration efficiency for example). I’m not sure about efforts outside the US.
Right BOB but when today in the HVAC industry we are stating viral reduction capability by a media filter probably that bioburden reduction is making a pressing need to have one?
Thanks for the good dialogue Himanshu - Keep up the good work!
Thanks for your kind words BOB, I’m kind of passionate about problem-solving especially when I breathe the world's highest polluted air, and with over 3 decades of HVAC industry it’s on people like us to solve in a sustainable manner. Help us, folks, we need the most!
What are the average cost and general process for obtaining FDA approval for a face mask?
Hi, out of curiosity we have measured, with our porometer, the pore sizes of MERV13 filters and come to MFP of 77um, while surgical masks have around MFP of 10um. Is there a relation between the pore sizes and the filtration efficiency/bacterial retention capability of masks?
Kathleen Owen: Interesting question. I would assume that a charged media filter would still drop in efficiency. The ions may cause this to happen faster. I have no data on the net efficiency changes that may occur in ion generators followed by filters. I'd like to see some. Anyone?
Kathleen Owen: I see the product coming. But if the filter catches the particle with the virus, the anti-microbial changes time to inactivate but not the amount in the air
Kathleen Owen: I would need to see the data on the specific device/use to be able to answer.