Sunday, April 2, 2017

DIY HEPA Air Filter


Airborne allergens can cause symptoms, and you can reduce the amount of airborne allergens in your house by using filtration systems.

There's a whole array of filtration systems that can be used, from furnace filters that goon the main furnace blower to systems that you can use in a room. They range from $100 to $800 for the high-end systems. And today I'd like to discuss the high-end system, and then also discuss a homemade system that should work fairly well at home, for a fraction of the cost.

This high-end system is an $800 system that will filter virtually every particle out of the air. A particle counter is measuring particles that are .3 microns in size,and it samples every six seconds. With a system like this, you can filter out the particles and thereby reduce allergy symptoms. So you can see we started off, I believe it was about 400,000 particles. And with this counting system, we can see that it goes down to essentially zeroafter a few seconds, after a few measurements. And now you can see we're 400, and down to zero. This is an incredibly effective, high-efficiency particulate air filter, or HEPA filter. And you can see that it'll scrub the air from about 400,000 particles per cubic footdown to zero particles per cubic foot.

You've seen the high-end filter system now and what it can do. It's incredibly powerful. But not everyone can afford a 6- or 800-dollar HEPA system. So there is something that you can do to filter your air, in a bedroom, for instance. And this is something that you can put together with pieces from your hardware store.

What I've got here is about a 12- to 15-dollar, 20-inch box fan;and a HEPA filter that you can buy for a furnace. So, this is a 20 by 20-inch HEPA filter. And it's important that you recognize that it comes in different levels of filtration. So, a MERV 13 filter is a very highly-rated filter that'll get a lot of very small --those 0. 3 micron -- particles out of the air. So this can simply be done by putting the filter in front of the box fan,so the air is blowing through the filter. And I'll just tape this filter here. You can see there's a direction for the air flow marked on the side of the filter. You'll see, if you look at yours carefully. And now I'll take the same counter and count the particles coming through the system. So, our ambient count, again, is about 400,000. And I'll turn the fan on and count the particles. And we'll see how they drop. Typically, this MERV filter will cause about a 90% reductionin those small . 3-micron particles. It measures every six seconds. And you can see I've gone down from 400,000 to 54,000. It'll probably hover around that point.

So this $30 -- 25, $30 system is filtering 90% of the particles out of the air. You'll probably want to put something like this in a bedroom, for instance, where you sleep and spend a good part of your day, to filter those particles out of the air. If you want, you can put them in other areas of the house, as well.