random COVID thought ?

[rb1957]

would it help to "soak " the recycled cabin air with UV, to kill of "anything", before returning to the cabin ?

another day in paradise, or is paradise one day closer ?

 

[LittleInch]

Somewhere on ET this had been discussed and the problem is the length of time the air needs to be exposed to UV makes it impractical.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IRstuff]

The shortest exposure time anyone has come up with is 15 minutes using either UVC or deep UV. Regardless, most airliners have HEPA filters in the air recycling path.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[rb1957]

surely "exposure time" is something we can work into the ECS system, sure re-design but ...

how effective are HEPA filters at catching viruses ?

If the virus is carried on moisture droplets, how about drying the air ? before re-humidifying it ... man, does that sound as circular as it looks ??

another day in paradise, or is paradise one day closer ?

 

[IRstuff]

surely "exposure time" is something we can work into the ECS system, sure re-design but

Not really; AC airflow might be around 1800 cfm --> 9.1 m/s at 1 ft^2 duct, so for 15 minute dwell, you'd need 8.2 km of ducting lined with UV lamps

HEPA filters are more efficient that N95 masks:

http://donaldsonaerospace-defense.com/library/files/documents/pdfs/042665.pdf

While they don't necessarily filter viruses; bare viruses are not a particular infection concern. The droplets and aerosols that contain them do mostly get HEPA-filtered

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[verymadmac]

Hmmm,would it not be doable if one used a UV laser and mirrors with efficiently at 99. something, but thinking about it, the hard bit might be all the solids in the air (skin flakes etc).

 

[Sparweb]

Somebody's got cute robots with blacklights on it that drives up the aisles between flights.

https://www.thesun.co.uk/news/12269023/jetblue-unveils-new-uv-light-to-kill-coronavirus/

...and in the airport...

https://www.washingtonpost.com/technology/2020/11/25/virus-killing-robot-airport/

Let me introduce another useful phrase: "Pandemic Theatre".
I'll leave it at that.

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[moon161]

Sounds like another aviation related topic 'Security theater'

 

[RoarkS]

Of all the fun stuff I've posted on... this actually hits close to home for my current real job doing environmental systems. Yeah we looked at going nuts with UV lamps. IRstuff nailed it.

 

[IRstuff]

People have analyzed some amount of data from air flight with infected people on board; no masks = infections, strict masking = ZERO infections.

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[WKTaylor]

Would be interesting to 'see' OEM reports on cabin airflow patterns, various flight conditions.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[Sparweb]

Trust me Wil,
They aren't that interesting.
You can reverse-engineer most of it. Draw a schematic, use the flow data from the ventilation blower (air cycle machine) specs, divide the flow rate through the manifolds in proportion to duct diameters. The answer makes sense. Refinements can be done within reason if you look at what kind of nozzles/diffusers/piccolos they use everywhere.

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[CWB1]

Why waste the money/time/effort? As seen this summer, hypochondriacs are going to be slow returning to unnecessary air travel so money spent catering to them would be needlessly wasted. The rest of us were back to flying by Memorial Day. Most airlines aren't ignorant, hence the quick drop of mask requirements once the public started flying again to avoid alienating the customer base. This is no different than the extra cleaning measures companies were taking last spring, after a few weeks they recognized that those of us actually in-store, in-office, etc didn't care and the rest didn't matter bc they're staying home. To be fair, when companies start forcing 100% onsite attendance again in January some of that may change.

 

[WKTaylor]

SW... I think You missed my point.

I believe that WHERE air flows [path] makes a significant difference. Airflow downward over an individual, exhausting at the floor [nearby exhaust] is a significantly different flow path than 'zones' or fore-aft thru a cabin.

I am somewhat familiar painting and composites/adhesive-bonding shops that have contamination control requirements with ventilating flow direction-specific paths in-thru filters and out thru filters surrounding working areas. Likewise positive pressure rooms are used for higher levels of contamination reduction such as for electronics repair/overhaul/assembly... that include positive in-flow thru filters and positive pressure venting. In the midst of all the contamination facility discussions are negative pressure rooms for containing dangerous contamination from escaping... specifically diseases/pathogens, radiological materials, dangerous chemical-compounds [including chemical-warfare], etc.

Also, I was part of a small group tasked to evaluate our cargo jet for patient transport. The aircraft was marginally acceptable/useful for small numbers of injured and most ambulatory patients... but was generally unsuitable for significant numbers of injured or 'sick patients'... and especially-bad for use with patients with communicable diseases. There were multiple seasons for this NO-GO rating for medevac... primarily surfaces [walls, floor panels, web-seats] that were hard/impossible to clean/decontaminate; a poor HVAC system that held the potential for long-term duct and component disease contamination; poor toilet/wash facilities for crew, med-personnel and patients; and 'certain issues' dealing with ambulatory mentally ill patients. WHAT A PAIN... MEDEVAC transport is more diverse than any most-other complex pax/cargo arrangements.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[moon161]

A friend of mine designed a medevac interior for eurocopter. No sharp inside corners and a slight incline on the floor so it would clean easy and drain out the back at cleanout time.

 

[Sparweb]

Yes, I did miss your point, Wil,

When involved a few years ago with the airflow effects on a cargo-combi, I did consult with the OEM about the effects on the air circulation system. Firstly, the OEM didn't do anything but basic certification for passengers, which was not as detailed as your scenarios for medivac patients will demand. Second, the bulk of the work was done by a sub-contractor to the aircraft OEM. Their data was locked up tight.

Recently, there are a lot of filtration devices on the market, either new or given a face-lift, driven by the obvious pandemic concerns. They are added as aftermarket modifications in most cases. I haven't seen any OEM installs, though that doesn't mean there aren't any like that. The ones I have seen are inserted at convenient locations, not necessarily at the most strategically important location, but pretty close. Handling these HEPA filters myself on a few occasions, they are VERY FRAGILE and need to be installed carefully. It's nothing like the air filter you put in your car, although looking at it, you could be fooled. Resting a pencil across the paper folds, they would start to crush.

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