A Homemade DIY “kinda/sorta” Air Purifier

Figure 1:  Kinda/Sorta air purifier from easy parts.

I wanted a room air purifier (I don’t know if there is a legal definition for such a thing, so mine is a “kinda/sorta” air purifier).  I found replacement cylindrical HEPA filters on the internet for about $40.  I plugged a small blower into the end of one of them (85 CFM, which is “cubic feet per minute”).  Voila – a kinda/sorta air purifier was born.  However, it takes a long time to reduce the particulate count (at least to my satisfaction), so I’ll probably upgrade to a commercial unit, or get a bigger cylinder.

The blower for most of these cylinders must be configured to pull air out of the cylinder, such that dirty air is sucked into the cylinder from 360 degrees of angle (since it’s round), and cleaner air is blown out of the 3 or 4 inch blower outlet.  Obviously the end of the cylinder opposite the blower must be closed off in some way.

The AQM (air quality monitor) shown is a Dylos 1100 Pro unit.  This is a pretty decent AQM in my non-expert opinion.  It is said to measure particle sizes as low as 500 nanometers  (.5 microns).  The reading on the left in figure 1 is the small particle count (greater than .5 microns and less than 2.5 microns),  while the reading on the right is the large particle count (> 2.5).

I have a horrific problem in the house with the smaller particles (I have seen as high as 600,000 small size particles per cubic foot).  I think an “indoor pollution” problem such as mine might not be that uncommon.   The small particle count is the probably the highest one in most peoples homes (non-expert opinion).  Most inexpensive AQM units do not measure particles smaller than 2.5 microns, which in my case would make them useless.    The Dylos 1100 Pro seems to do it.  The reading in figure 1 must have two zeros added to it, for a “particles per cubic foot” value (making the real reading equal to 17,500 particles per cubic foot).  Before I turned the unit on, the reading was 44,500 particles.  But, like I said, it took a long time to get there.  I’m looking at maybe a Honeywell or something like that, but in the meantime this was an educational DIY.

The CFM of the blower has to be at or below the specified CFM rating of the filter cylinder, or particles will push through it, and its lifetime may be lowered.  So, a 7.5 inch diameter cylinder from some manufacturers is good for about 85 CFM, and a 10.5 inch diameter cylinder filter from some other manufacturers is good for about 250 CFM.  Mileage varies, so ya have to know the specifications.  After all was said and done, I didn’t save much money (parts were 65 bucks, compared to 150 bucks for commercial unit), so it’s probably better to go with a commercial unit.

Figure 2:  Dylos AQM seems to be superior to most (non-expert opinion)

In figure 2, the Dylos is showing the initial value of particulates in the room, before turning the blower on.

BTW: Duct tape is not the proper way to connect the blower to the filter – and my setup does not constitute advise for anyone else to use it!  I’ll be thinking about a proper connector for the blower in the unlikely case that I keep the little DIY unit (maybe it can clean a closet or small room, LOL).

Note:  I’m not an HVAC expert, so none of this is advice for anybody.  There are probably other things to watch out for, etc.  Dylos is a tradename of Dylos Corporation, and this author and site has no affiliation with them.


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