What is a HEPA filter

HEPA filters

创建日期 2022年6月17日

HEPA is one of most used anacronyms in the industry. Our latest podcast briefing helps you discover just what a HEPA filter is, how it works and why it’s important. Join Michael Feldtmann, who has a thirty year pedigree with Camfil, in our latest twenty minute podcast right now.

The transcript

Michael Feldtmann  0:02  

If you're in the hospital, hopefully you're not assuming you are in the hospital and you're lying in the operating theatre. Then normally, for example, filters in the ceiling above the patient, protect the patient from particles coming into the room.


Dusty Rhodes  0:21  

Hello, and welcome to Let's talk at clean air where we find out more about how clean air can affect the quality process for you and the workplace. This month, we're taking a look at one of the most used acronyms in the industry HEPAto find out just what it is, how it works and why it's important. My name is Dusty Rhodes and joining me to explain all of this is someone very familiar with HEPA. He has a 30 plus year pedigree with camfil, where his responsibility includes all air filter products, the housing systems for them, and ensuring that they all run with the highest efficiency possible. In addition, as the German expert in the ISO standards for HEPA filters, he is part of the German and international standardization process from high air filtration purposes. It's a pleasure to welcome and to learn from Michael Feldman.


Dusty Rhodes  1:11  

How are you?


Michael Feldtmann  1:11  

I'm good. Thanks a lot.


Dusty Rhodes  1:13  

So every single program in the series so far, we've heard HEPAHEPAHEPA, HEPA, HEPA exactly do the word letters HEPA stands for?


Michael Feldtmann  1:21  

Well, it's, as you said, already, it's an acronym, high efficiency particulate air filter. So you see high efficiency, that gives you the direction where we go. So very high efficiency to small particles, to protect sensitive processes, really, to file stage protection.


Dusty Rhodes  1:44  

And when you're talking about high efficiency are you talking about, it's particularly good at getting particularly small particles,


Michael Feldtmann  1:50  

Wellif you if you want to understand our HEPA filter is by let's say, being used and how it's working, it's a mechanical filter. So it's has a very fine structure of the media. And the media itself has been made to capture very small particles on a very high level. So that's the idea. Because the sensitive processes, which we can probably later to explain, the sensitive processes have to be protected. And that's what the HEPA filter or HEPA filters are for.


Dusty Rhodes  2:29  

And how then does a HEPA filter, then protect the environment?


Michael Feldtmann  2:34  

Well, it's the environment, you have to understand that the HEPA filter is the final stage of an air ventilation system, right, youget the


Michael Feldtmann  2:42  

air into the building, normally, and then you have a process somewhere in the building. Let's take life science, for example, you were producing, I mean, it's very actual, you're producing vaccines. For example, if you want to produce vaccines, you have to ensure that the production is being well, let's say that the amount of particles in the room is very low, so that there is no effect on the product. So then you put a HEPA filter on the final stage of the air ventilation system to reduce the amount of very small particles to a level where you can produce that's more or less in very short word. For example, for the pharmaceutical industry, when you look at the micro, micro electronic industry, when you produce microchips, for example, then also small particles can affect the structure of a wafer on other, let's say, of a normal piece of electronic equipment. So that's where HEPA filters are used. That's one part but also, when you look at protecting the environment, what you mentioned before, like when you have laboratories, high end bands, laboratories, the exhaust air of these laboratories are filtered with HEPA filters, to protect the environment to ensure that there is nothing coming out. So that there is nothing really coming out of the system.


Dusty Rhodes  4:14  

That's something that I had never considered before. So you need to protect the air that is coming in. But of course, there are things that could be happening in the facility. So you need to expect to protect the air that is leaving the facility as well.


Michael Feldtmann  4:25  

Correct, correct. That is that is something which is really important also, today in the actual situation, because for example, if you have an isolation room, when you talk about people who are suffering, then you want to protect the other rooms or the outside so that nothing is coming to the next room or to the outside. So for example, viruses are not coming into that room. So that's why you need also using HEPA filtration.


Dusty Rhodes  4:57  

Does HEPA  filtration something along the lines of where you would Have a rough filtration purpose that would say capture 80% of particles. And then later on in the chain, you've got your HEPA filter which carry it which captures the remaining 20%. Or you could you could


Michael Feldtmann  5:14  

say like that I would say, depending on the preferred tracer states you have, but when you look at the HEPA filters, you normally think about Okay, what is the efficiency on very small particles? That is because the filter itself is not like a sifter, but there are a few mechanisms inside the media which is collecting efficiencies and all these collecting efficiencies together, they show that with a HEPA filter, you have a very high efficiency against very small particles and then we are talking about not 80% but then we are talking about 99.95% or even 99.995% H 14 and as a HEPA filter. So, that is the difference, I would say and you are then sure that the process afterwards is being secured.


Dusty Rhodes  6:18  

So can you give me some examples, real world examples of where HEPA filters are used?


Michael Feldtmann  6:24  

Yeah, well, the for example, if you're in hospital, hopefully you're not but assuming you are in the hospital and you are lying in the operating theatre, then normally for example, filters in the ceiling, above the patient, protect the patient from particles coming into the room for example, or as I mentioned already, when you go to the pharmaceutical industry, even when you fill up glass vials, where the vaccines, these glass vials have to be sterilized and here you have the HEPA filtration inside the sterilization tunnel. So, the filter itself can be installed in the ceiling. For example, also in the microelectronic industry, when you produce microchips, as I said, the these filters are produced are installed in the ceiling. But also and that is quite I would say new or the idea is very common now to have air purification system transportable systems also adapted with HEPA filtration to take them from room to room. So there are various applications. And you will find that also in the food and beverage is a good example. Also, when you look at your meat, when you when you look at the packages, it would say, packed under clean environments. That is exactly what we're talking about it is a HEPA filter in the end in the machine to protect the product.


Dusty Rhodes  8:02  

And how do we know that the HEPA filter is a fit for purpose


Michael Feldtmann  8:07  

that is clearly regulated, you need to do 100% test of every HEPA filter before it is leaving the facility. And this test is being done with efficiency. So you test the efficiency. And with that, you test the filter class. And then you test that the filter is leak free, because you can imagine of these sensitive productions, they need to be 100% sure that there is no leakage in the filter. And the pressure drop, for example is also being tested. Why that? So you completely scan the filter, you completely check that the filters, okay, and you have an individual test certificate. That's where the, let's say the quality behind it. That's where the end user, as the security the end user has, this has the security that the filter is fitat the filter is okay. And that's where the customer has to insist on. This has to be done.


Dusty Rhodes  9:22  

I get the impression that a HEPA filter is to air like Fort Knox is to money. It's that level. Am I getting the right idea?


Michael Feldtmann  9:32  

Fort Knox Yeah, wow.


Dusty Rhodes  9:35  

I mean, it's a it's very, very, very, very high level as it is it.


Michael Feldtmann  9:38  

is very, very high level and that's a little bit the problem we have today that a lot of the customers are not our customers, a lot of the society is using HEPA in all different ways they are saying HEPA filter HEPA filter HEPA filter, but when you look at real HEPAfiltration it is clearly specified and if we are talking about how There is a standard behind that. EN1822So there's a standard, really regulating What is HEPA? And what is the performance and how you have to test it. So that's some of them. Some of the, let's say the society is using this for, yeah, for a good filtration. But as you said, it's a very high filtration so that you have to have in mind. 


Dusty Rhodes 

So how is the filter actually manufactured? How does it how does it work, 


Michael Feldtmann

you normally see a square or rectangular shape, you have a frame, and then you have a V shaped pleated media. And normally, so the frame and the media filter pack what we call it is glued together. And then you might have a gasket on the filter as well. So the normal size is square or rectangular, or it can be even round, depending on the application. And the most critical thing is that the combination of brain gasket, filter media is completely sealed, you can imagine that this has to be really sealed, and according to the filter class you want to reach so you can do, I would say a lot of different variations, fitting for the purpose, the customer needs it.


Dusty Rhodes  11:28  

Now, like anything in the world, there are various types of HEPA filters and various standards of HEPA filters. How do you compare HEPA filters against each other?


Michael Feldtmann  11:39  

That's a good question. When you want to compare a HEPA filters to each other, as I mentioned before, the test has been done at the production after the production before delivering the filters, and the end user, the customer, he cannot really check directly the filter class because that's you can imagine quite a lot of investment to do that the test certificate, the test procedures are not that easy. The End User can compare pressure drop, or the filter at a given airflow. That's what he can do. And what can be done is to check in the installation, what has been achieved. So if the cleanroom class is achieved, for example, and that's what you can do, and when you can want to compare different productions, then you won't have to insist, as I said before, on really 100% certificate 100% proven quality. That'sthe that's the background.


Dusty Rhodes  12:48  

But who gives that 100% certificate


Michael Feldtmann  12:52  

that has been done by the producer of the filter, he has to do it normally. But we see on the market as a lot of other things. We see some, yeah, someone who's not 100% following. But that's not whatwe are talking we stick to the certificate and that's or to the standard. And that's what is being done by the producer. In this case, it could be camfilSo you deliver that. And the customer, the end user like is then sure, should you


Dusty Rhodes  13:24  

Should you watch out for to say that this is certified according to and then look out for the ISO specification and make sure that that is correct.


Michael Feldtmann  13:31  

Correct. EN1822. So that is correct. And the customer has the security that what he's installing gives the right protection for the process.


Dusty Rhodes  13:45  

And how dangerous would it be if you were to not go for a 100% filter, and you got something that was 95% effective.


Michael Feldtmann  13:55  

Depending on where you are, I mean, it's depending on in which application you're using the filters, some applications, to be honest, there would be not a big difference. But it depending when you are, for example, in a high advanced laboratory where you want to protect the people outside, there could be major difference, because 95% to 99.995%. That's a very big difference. So that's when you when you then imagine, which is coming, what is coming through can make a difference.


Dusty Rhodes  14:30  

I'm trying to understand how effective they are. Because for me, you know, I'm thinking about the filter that's in my vacuum cleaner. And that obviously is not an HEPA filter. Sowe'retalking something way, way, way, way higher. And then I'malso kind of thinkingabout the viruses as well. And how effective are HEPA filters against viruses in the airstream because those viruses must be tiny.


Michael Feldtmann  14:52  

Yeah, why the viruses are very tiny and take the COVID situation now. So we are talking about viruses, which are in the range of 0.08,to0.16micro meterSo micro meter is a 1,000th of a millimeter. So that's extremely small. On the other hand, when you see HEPAfiltration HEPAfiltration is being measured and be tested, as I said, at the MppsSo at the most penetrating particle size, and this particle size is in the range of 0.120 point two micro metersSo you can imagine that they have a filter, when you directly compare it, you would have an efficiency of 99.995% against these sizes. But you have to have in mind that a virus normally is connected to a particle or to an aerosol in or at an aerosol. So then we are talking on probably sizes of 0 point five to five microns, but the efficiency then is much bigger. So we are talking close to 100%. You see, the HEPAfilters is really protection against viruses. For sure.


Dusty Rhodes  16:19  

They're very, very high end, high efficiency. What I'm thinking is, how often should these be replaced? I mean, how long do they last?


Michael Feldtmann  16:30  

Depending on the installation, you would normally talk about installation of when you do a normal in, let's say, in the life science industry, you're talking about five to eight years normally, that when you do for example, when you use a HEPA filter inside an app you fire where you constantly go through the HEPA filter, and you have them installed in a room with not so good pre filtration, you might have one and a half, two years, two and a half years. So depending really on the application,


Dusty Rhodes  17:10  

that'sa big difference. So how do you know or how do you monitor the effectiveness,


Michael Feldtmann  17:14  

the effectiveness in in, in the normal installations, when you have a clean room, for example, the filters are being monitored every six months to a year and the cleaning list level of the cleanroom is being monitored as well in that period of timeSo you look, is it still working? Okay? That is one thing. And the second thing which you normally monitor is the pressure drop. So you monitor the pressure drop. And then you can see okay, is a time for changing the filter. So depending really, where which application you have,


Dusty Rhodes  17:54  

speaking of changing filters, what kind of maintenance is do you do you use a filter and you just take it out and dispose it when you need? Or is there a way of conducting maintenance on the filter so that you don't have to be constantly buying a new one?


Michael Feldtmann  18:13  

I think there are two things behind the question. One thing is that you normally dispose the filter into a bag, and then it has been disposed depending on really also depending on where the filter is coming from. So when you're in a nuclear power plan, for example, and you have an exhaust, you would you would dispose the filter in a different way. That is one thing. The second thing is that because of the structure of the media, the media is very fine has a very fine structure. And this media, the normal media for HEPAfiltration cannot be how do you say cannot be cleaned, you need to change the filter. That is one thing. And on the other hand, if you think about how to clean a filter, and I mean thesefilters are meant to be used against very small particles, and then imagine you want to clean it. That's tricky. You would normally destroy the media and you would not take out all the particles. So to answer the other question is no, youhave to dispose the filter and you are not cleaning.


Dusty Rhodes  19:28  

And what kind of other questions come up with people when you were when you were talking to them?


Michael Feldtmann  19:33  

As you mentioned a lot of them I think lifetime for example isa big thing. Then what we talked about what we already talked about, what are the differences? Where are the differences? How can I see in brackets differences? This the last question is why would say or not less. But there's another question Okay, where can I install HEPAfiltration inside my building or in Inside the application I have talking about viruses. What shall I do? What can I do? And in this case, you can upgrade the air handling unit. So the recirculating air, the air coming from the room, you could install their additionalHEPAfiltration. And that's most common. Now, when you do not want to do that, then you installed in the room HEPA air purifier. And that'smore or less the main question nowadays, because the situation is a little bit different. A lot of let's say normal people, like you and me are discussing say, Okay, how can I put a HEPA filter in my, in my home, in my home or my home or in my facility? So then you can use the HEPA air purifier. But you have to really insist that on the filter itself is as we already discussed, the proven quality.


Dusty Rhodes  21:01  

And one final question, the HEPA filter, is it something that is installed into the existing air system within a building? Or is it something that you can add on as an extra stage,


Michael Feldtmann  21:15  

when you have an installation, when you have an air handling system, you can install filters in the air handling unit. But then you need you need to have a space to put that in. That's clear, if you don't have the space, you have to do an additional housing which is then delivered with a filter. So you can upgrade that to that extent. And you can when you think over the recirculating You can also install filters there are specific filters but you need the space for to do the space first. And what is the what is a little bit more tricky is you need to have also the ability that the ventilation system can overcome the pressure. I mean, you are generating a pressure when you put this sort of filter in the system. So the system itself need to be capable of Yeah. Doing the right thing having enough air in the room otherwise, you would say that's not a good idea.


Dusty Rhodes  22:23  

Excellent. Well, listen, that has certainly opened my eyes. Michael Feldman from Canfield, thank you for filling us in today.


Michael Feldtmann  22:29  

Thanks a lot. Pleasure.


Dusty Rhodes  22:34  

That wraps it up for this episode of Let's talk at cleanair. If you would like to find out more about HEPA filters just follow the links in the shownotesyou'll find those in the description of this podcast on your phone or whichever device you're listening to us on right now. painter links, contact details and anything else that you might need to get more information. Our podcast was produced by camfill, a world leader in the development and production of air filters and clean air solutions to stay up to date on how clean air can affect the quality process for you and the workplace. Do like follow or subscribe so that you will get our next podcast automatically onto next time for myself Dusty Rhodes. Thank you for listening and take care