Project Help: Air purification; deep UV led lights

Replies

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  Harshad Italiya

  Few moths ago I was in one tech fair where one stall was related to your project they are selling such product which is air purifier and it's cost was around 5K INR so i don't think that LEDs are much costly i'll try to contact some dealer and let you know if found any.
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  ChadT

  godfather

  Few moths ago I was in one tech fair where one stall was related to your project they are selling such product which is air purifier and it's cost was around 5K INR so i don't think that LEDs are much costly i'll try to contact some dealer and let you know if found any.

  That would be great! Please keep in mind two things: We only need small LED's which would fit in a small space such a breathing device, and being students, we are on a very limited budget. Thanks, and if anyone else can assist me I would really appreciate it!
• 

  Harshad Italiya

  ChadT

  That would be great! Please keep in mind two things: We only need small LED's which would fit in a small space such a breathing device, and being students, we are on a very limited budget. Thanks, and if anyone else can assist me I would really appreciate it!

  You want to assemble it in Breathing device?? The device I am talking was bigger in size.
  Ok I will inquire about LED let's see !
• 

  Ramani Aswath

  ChadT

  That would be great! Please keep in mind two things: We only need small LED's which would fit in a small space such a breathing device, and being students, we are on a very limited budget. Thanks, and if anyone else can assist me I would really appreciate it!

  As a biomedical technologist I have used UV air disinfection for many years, both for clinical and manufacturing environments.
  Firstly, UV is not applicable too moving air streams because contact time is minimal. Secondly, various regulatory agencies prescribe limits to Ozone generated along with the disinfection. In my opinion you may not be able to achieve dynamic disinfection in a wearable breather unit.
  
  Please see this quote:
  Quote:
  Air Disinfection
  
  UVGI can be used to disinfect air with prolonged exposure. Disinfection is a function of UV concentration and time, CT. For this reason, it is not as effective on moving air, when the lamp is perpendicular to the flow, as exposure times are dramatically reduced. Air purification UVGI systems can be freestanding units with shielded UV lamps that use a fan to force air past the UV light. Other systems are installed in forced air systems so that the circulation for the premises moves micro-organisms past the lamps. Key to this form of sterilization is placement of the UV lamps and a good filtration system to remove the dead micro-organisms.Ultraviolet Germicidal Irradiation Cite Note 10 For example, forced air systems by design impede line-of-sight, thus creating areas of the environment that will be shaded from the UV light. However, a UV lamp placed at the coils and drainpan of cooling system will keep micro-organisms from forming in these naturally damp places.
  ASHRAE covers UVGI and its applications in IAQ and building maintenance in its 2008 Handbook, HVAC Systems and Equipment in Chapter 16 titled Ultraviolet Lamp Systems. ASHRAE's 2011 Handbook, HVAC Applications, covers ULTRAVIOLET AIR AND SURFACE TREATMENT in Chapter 60.
  Endquote
  
  Ultraviolet Germicidal Irradiation
  
  However, it is an interesting concept if it can be made to work.
  GF may see if the OP can submit this to the ongoing "design the future" contest.
  
  If I find anything more on this, I shall revert.
• 

  ChadT

  bioramani

  As a biomedical technologist I have used UV air disinfection for many years, both for clinical and manufacturing environments.
  Firstly, UV is not applicable too moving air streams because contact time is minimal. Secondly, various regulatory agencies prescribe limits to Ozone generated along with the disinfection. In my opinion you may not be able to achieve dynamic disinfection in a wearable breather unit.
  
  Please see this quote:
  Quote:
  Air Disinfection
  
  UVGI can be used to disinfect air with prolonged exposure. Disinfection is a function of UV concentration and time, CT. For this reason, it is not as effective on moving air, when the lamp is perpendicular to the flow, as exposure times are dramatically reduced. Air purification UVGI systems can be freestanding units with shielded UV lamps that use a fan to force air past the UV light. Other systems are installed in forced air systems so that the circulation for the premises moves micro-organisms past the lamps. Key to this form of sterilization is placement of the UV lamps and a good filtration system to remove the dead micro-organisms.Ultraviolet Germicidal Irradiation Cite Note 10 For example, forced air systems by design impede line-of-sight, thus creating areas of the environment that will be shaded from the UV light. However, a UV lamp placed at the coils and drainpan of cooling system will keep micro-organisms from forming in these naturally damp places.
  ASHRAE covers UVGI and its applications in IAQ and building maintenance in its 2008 Handbook, HVAC Systems and Equipment in Chapter 16 titled Ultraviolet Lamp Systems. ASHRAE's 2011 Handbook, HVAC Applications, covers ULTRAVIOLET AIR AND SURFACE TREATMENT in Chapter 60.
  Endquote
  
  Ultraviolet Germicidal Irradiation
  
  However, it is an interesting concept if it can be made to work.
  GF may see if the OP can submit this to the ongoing "design the future" contest.
  
  If I find anything more on this, I shall revert.

  Thank you for your response. We did see this wiki info last week, but are hoping that (moving) air in a very confined space can possibly be purified with UV in a very short timeframe since such a small volume is being completely exposed. Also, we have been reading that ozone should not be produced as long as our UV is above 254 nM. Is this true? In your experience, how much exposure time is required to be effective? Has this minimum timeframe been proven necessary, or more as a "likely more effective"? Commercial air systems involve a very large volume of air, so it could be possible that the higher the volume of air, the more exposure time necessary. Is this a flawed theory on my part? I'm not by any means doubting your expertise, and in fact really want your additional input because this entire concept is new to my team, and we are eagerly learning as we go. And that would be great if we could submit this to the "design the future" contest, but we need a little more time to work out the details of our concept first.
• 

  Ramani Aswath

  ChadT

  Also, we have been reading that ozone should not be produced as long as our UV is above 254 nM. Is this true? In your experience, how much exposure time is required to be effective? Has this minimum timeframe been proven necessary, or more as a "likely more effective"? Is this a flawed theory on my part? I'm not by any means doubting your expertise, and in fact really want your additional input because this entire concept is new to my team, and we are eagerly learning as we go. And that would be great if we could submit this to the "design the future" contest, but we need a little more time to work out the details of our concept first.

  Unfortunately UV rays do not 'seek and destroy'. If a microorganism is in the path and gets a sufficient dose it will get killed. This is why a short path perpendicular to the beam is insufficient to effectively disinfect. Most biomedical use of this process is in essentially static.
  
  There are circulating units available. However, these also operate in a closed volume. The room air is sucked in, bathed in the light and then sent out back into the room. Usually this is done in unocuupied spaces to avoid hazards.
  If you think a little deeper, you will realize that air at atmospheric pressure is almost all empty space. The UV rays are just passing through emptiness and not doing any work. There is a dose-time parameter that has to be considered. Higher the intensity greater the chance of a successful interception by a micro-organism. The size of the organism (>0.2 micrometers) is much larger than an air molecule so the rays will be intercepted. But the number of organisms is much less than the number of molecules, which will shield the rays as they do in the atmosphere.
  All may not be lost. If you consider the tidal volume (about 500 ml/breath) and ten breaths/minute you can expect about 6 secs between breaths. If you can arrange your device to have a dead volume of about 500 ml Then you get about 6 secs exposure time, which may suffice.
  You can cheat a bit by bouncing the UV back and forth. Aluminium surface reflects UV. If you make a spiral of thin polished aluminium foil with a gap of say 3mm between successive walls, let in the air through a porous/perforated tube along the vertical axis of the spiral sothat the air moves outward and exits the periphery of the spiral you have the air spending some time in the chamber. The UV LEDS (or whatever) are arranged in a manner where the rays continuously bounce arund the spiral back and forth, in effect catching the organisms coming and going as it were.
  As I mentioned earlier the enclosed volume should be at least one breath volume.
  
  You are right about Ozone and 254 nm.
  
  In my opinion you will give yourself some elbow room if you think on these lines.
  
  One more thing. Any biomedical device will have to be validated for intended purpose. All applicable standards (in the country of manufacure and that of sale) must be adhered to. All materials must be compatible with all conditions of use.
  
  Regarding the contest, you can submit at this level of development. However, you have to ensure about IPR protection if that is of concern to you.
• 

  Ramani Aswath

  An update:
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