today we’re going to talk about UV light implementation and air purifiers now ultraviolet germicidal irradiation UV GI for short is used in industry to kill germs in circulating air or water systems now for the rest of this video we’re going to talk about ultraviolet germicidal irradiation simply as UV GI we’re gonna just use this short term there UV GI it’s a lot easier to say and ultraviolet germicidal irradiation is quite a mouthful
so again for the rest of this video we’ll talk about UV GI when we talk about ultraviolet germicidal irradiation in any case UV GI is implemented in industrial air and water systems as we just talked about and it’s implemented in a way to ensure that it’s as effective as it possibly can be and in order for it to be effective as possible there are four components that we need to look for the first is that the air or water is exposed to the light for a sufficient amount of time to ensure that the germs are killed this is commonly called dwell time it refers to how long the air is actually over the light
so what you want is you want maximum dwell time you want the air to be over the light as long as possible the second component that’s key to a UV system being effective in this type of implementation is that the light is of a sufficient intensity to actually kill the germ if the light is of two lower wattage then it’s not going to be able to kill the germ effectively the third component we need to look for is that the air or water can contain certain particles and these particles can actually shield the germs from the light
so in industrial systems they need to take into account there’s any type of particles in the air or the water how is that gonna affect the UV light actually getting to the germ to actually kill that germ and finally the fourth component we need to look at is which germs are actually being killed here different germs have different resistance to different types of ways of killing them
so not all germs are going to be killed equally effectively with a UV light so the type of German vault is definitely another factor that needs to be considered as you’re implementing UV GI in a industrial setting in air system so so far we’ve talked about you vgi being employed an industry to kill germs and now we need to kind of pivot towards how its implemented in a residential setting in an air purifier like this one I have to the right of me
so in order to do that let’s go over those four components we just talked about those four key factors in determining the efficacy of a UV GI system and let’s see how well a air purifier implements those four factors we just discussed so of course the first thing we talked about is that you vgi efficacy is dependent on the actual dwell time how long the germ is over the light and an air purifier can do this better or worse depending on several factors one thing that can be done to increase dwell time is to simply increase the surface area of the light so the larger the light the longer the germ will be over the light just because there’s more light for the germ to travel across another thing that can be implemented is reflective surfaces a light is obviously reflective including UV light so by employing different reflective surfaces inside the air purifier that light can bounce around and have more dwell time over the germs finally you can implement the light parallel to air flow so
as the air is coming in if you implement the light parallel to air flow the air is going to be over that light as long as possible once again if it’s implemented perpendicular to airflow the air is going to go right over the light and it’s really not going to be over the light from very long so that’s definitely something to look out for as well is the light implemented in a perpendicular or at parallel direction relative to the flow of air so those are things to look for an air purifier to make sure that dwell time is going to be as long as possible so how do air purifiers actually do and the truth is that the most popular UV models on the market actually don’t do so well at all with this type of implementation on the table here today we have the germ guardian AC 4825 and the UV light is actually implemented right at the top here so this unit is a little bit unique that the air comes in through the back of the unit and it travels through the front of the unit the clean air is coming here through the front of the unit so in the back of the unit here there is a carbon filter and then a HEPA filter and then the air is coming in through the back .
here so all the air is getting pulled in here the UV light is right at the top here so there’s an area up here where there’s a metal shield and behind this metal shield is the UV light so in removing this metal shield you can see up here the light is right up here so the interesting thing here is the fact that the light is not actually implemented in any way that you might want it implemented to be as effective as possible for UV GI the the light is up here.
in its own separate compartment it’s surrounded on three different sides by non reflective surfaces the metal shield here on the inside of the metal shield it is somewhat reflective however on three sides here it’s non reflective and the bigger problem here though is the fact that this light is all the way in its own separate compartment up here so as the air is coming in through here the the light is completely isolated in the setup here so for us we really question if the UV light is doing anything at all here and we’ll talk a little bit more about that later on before we continue though we do want to note that there are other German Guardian models that do have a better implementation the AC 50 to 50 for example actually does have a UV light that extends lengthwise.
here down the back of the air purifier and so it’s really right there in the middle of things when it comes to the air coming through and that type of implementation is gonna be much better the thing is that this AC 48:25 is very popular it’s a popular model for people looking for an air purifier it also has a UV light and so the fact that it’s implemented so poorly in this model is definitely noteworthy and that is the reason why we use it here as an example today now we just talked about how on this particular unit and other German Guardian units as well the UV light is implemented quite poorly for maximum dwell time and the fact is that that really isn’t .
the biggest problem here the biggest problem is the fact that these units are primarily used for filtration the HEPA filter that fits in right here he’s going to capture particles and the thing is for that HEPA filter to be as effective as possible the air has to travel through here as much as possible so for maximum particle filtration you want the air to travel through the filter and you want that air to keep on traveling through the filter over and over so as this air purifier is implemented in a room eventually it’s going to go through all the air in the room and once it’s gone through all there in the room it’s gonna keep on processing air in the room and it’s gonna repeatedly process there in the room to keep on removing particles over and over and the thing is you want to do that as quickly as possible with an air purifier the higher the CFM that the greater the output of the air purifier the more effective particle filtration will be and the problem there is that for UV GI you want exactly the opposite you want maximum dwell time you would want the air to travel as slowly as possible you would want as a little air as possible per unit time to go through the system pass the light and so what we find is that particle filtration and UV GI are two opposing things they.
they require two opposing things in terms of what they need to be effective with particle filtration you want maximum CFM you want maximum output you want a maximum amount of air to travel through the unit as quickly as possible to really capture as many particles as quickly as possible for UV GI in order to kill germs you don’t want that same level of output necessarily you want the air to travel more slowly you want the less air to travel through so that there’s a maximum amount of time for that air to be exposed to the light to actually kill the germs in the air now.
the second factor we talked about earlier that determines UV GI efficacy is the wattage of the bulb and the fact is that units like this germ guardian again they just don’t have very high wattage bulbs and again it’s really questionable whether the bulbs have sufficient wattage to actually kill germs this particular AC 4825 that we have on the table only comes equipped with a five watt bulb there’s a smaller model the AC 4100 that model only comes equipped with a 2 watt bulb so the wattage is extremely low on these models and that low wattage again really makes us question whether the light can even be effective in the first even if it war let’s say implemented better and a better location in here would it even be effective with such a low wattage that’s something that is a real big question for us again for you V GI of efficacy to be as great as possible you want a maximum wattage bulb you want the bulb that has as much wattage as possible and these bulbs in here in these residential air purifiers are low wattage bulbs the third factor that have determines you vgi efficacy again is particle concentration in the air or water here we’re talking specifically about air and what happens is as air is traveling through the system particles can actually act as shields for the germs so you want to have as few particles as small particles as possible in there and here air purifiers do really well .
again air purifiers actually are equipped with a HEPA filter that is going to capture those particles so the particle concentration in the room is going to gradually decrease with an air purifier implemented and by decreasing the number of larger particles in the room you’re decreasing the concentration of particles that are going to act as shields for the germs so in that way an air purifier does quite well for you vgi efficacy finally we talked about how you vgi efficacy is dependent upon the actual characteristics and nature of the germs involved and the fact is that here the air purifier can’t do anything it really comes down to the individual to know what type of germs are involved in industry you may be able to test the air water system or test the surrounding area or have some understanding of the germs and the nature of the germs that might be involved in that system for somebody at home using an air purifier you’re probably not gonna have any idea what type of germs you’re dealing with and.
so it’s really no no fault of the air purifier though in that situation the air purifiers cannot determine the characteristic of the germs and how effective it’s going to be against those germs the germs are just going to be the way that they are in the actual area where you’re using the air purifier so what have we learned so far in this video we know that UV GI is effective we know that u v GI is effective enough to actually be in commercial settings in industry we’re killing germs is important and we know that for sure so it’s not a question of whether UV light is effective in killing germs it absolutely is effective in killing germs now the fact is that we also know that residential air purifiers for the most part and definitely some of the most popular units on the market such as this unit from germ guardian those units simply do not implement UV GI very well the fact is that again the location of the bulb the direction of the bulb the reflective surfaces around the bulb the wattage of the bulb all of these factors contribute to making the implementation in such an air purifier quite poor so UV GI is effective but its implementation in your average residential air purifier is not going to be that great at least for some of the most popular units on the market and lastly we also know that UV GI and particle filtration are essentially opposing forces for particle filtration you want maximum air flow you want that air to travel as quickly as possible to be processed as quickly as possible for UV GI efficacy you want exactly the opposite you want maximum dwell time you want that air to really be exposed for that light as long as possible and so UV GI and particle filtration are kind of two opposing forces there and when it comes to air purifiers that are primarily intended as particle filters this presents quite a problem right there from the get-go so in kind of wrapping things up here we want to make one final very important point and .
that is the fact that you don’t have to kill germs to filter them from the air a germ is essentially nothing more than a particle when it comes to a HEPA filter for you or me for us to define different particles we can say that this is a particle that is not a particle for the HEPA filter anything that travels through there is a particle and a germ has mass it’s a object in space and as it travels through the filter the HEPA filter is capable of capturing that particle that germ it’s one in the same to the HEPA filter and the germ does not have to be killed it does not have to be dead for the HEPA filter to capture it so what we’re saying here is that the UV light implemented with a particle filter like an air purifier is essentially a redundant measure to remove those germs from the air the germs are going to be removed from the air with the air purify the air purifier is going to be able to remove those germs a UV light in the setting is redundant.
and it’s not necessary you do not need to kill the germs to filter them from the air and so our bottom-line recommendation when it comes to UV lights UV air purifiers UV lights implemented it in air purifiers when it comes to recommending UV air purifiers we certainly don’t mind them this is a fairly good air purifier it filters particles fairly well so the UV light is not taking anything away from that so we definitely would not say stay away from UV air purifiers we would not say if you see a unit with a UV light understand that it’s probably going to be implemented poorly and for that reason you need to stay away that’s certainly not the case we would say that look for an air purifier that is going to be a good quality that is going to have good energy efficiency that’s going to have good noise output and that means low noise output look for an air purifier that is going to do everything that an air purifier needs to do very well it’s going to have the settings that you need that’s going to have a remote if you need that that’s going to have good gas filtration if you need that etc etc all these other factors we would stress those other factors in looking for an air purifier and if the air purifier does have a UV light implemented .
we would say that that’s fine you know that’s that’s not a problem but don’t rely on that UV light don’t think that because it has that UV light that you’re going to get that extra level of filtration that you’re going to get that extra level of air purification in the room that’s simply not the case with most UV lights implemented in residential air purifiers so again UV GI is effective UV GI is not implemented very well in most air purifiers but at the same time UV GI is not really necessary with air purifiers so what we would recommend is that you take a look at top rated units we will have a link to those in the description to this video those top rated units may or may not have UV lights but now you know that you don’t really need a UV light for your air purifier.