Anybody have experience designing air filters?

[sciguyjim]

I'm trying to design a high flow, high efficiency air filter and I have no experience so it's all guesswork. I also have no test equipment to guide me. I'm looking for someone to evaluate my design and let me know if it sounds ok or not. For months I've been doing dozens of web searches but can't find the kind of info I want. Thanks.

 

[Rich2001]

Download the Aerosol Calculator Program from TSI

http://www.tsi.com/particle/downloads/software/software.htm

Look at the TSI site they manufacture test equipment for air filter testing, expect to spend lots.

The University of Minnesota at one time had a short course on aerosol measurement. If they are still giving it go! very good course with lots of information an good contacts in the filter testing field.

 

[dvd]

What is the particle size(s) you hope to filter out, what type of efficiency are you looking for on your smallest particles, and what is the airflow rate and face velocity through your filter? Can't you purchase anything to meet your needs? You should try going to a technical library at the nearest university instead of looking for information on the internet. If you want to build a test stand you could start by referring to ASTM F 778-88. I believe there are other ASTM standards on filter testing also, but I am only familiar with the above mentioned.

 

[sciguyjim]

Dvd,
I really don't have any data to go on. I've had trouble finding info about the capabilities of current filter types that I could base my designs on. All I know is I want a better filter than the simple paper types available. I don't like the look of the high airflow, "high efficiency" filters out there either. I feel I can get higher efficiency with a slightly different design.

I'm currently looking at a filter area of about 93 sq. in. and a flow rate of about 250 CFM, maybe going as high as 500 CFM briefly. This breaks down to be a maximum of a little over 5 CFM per sq. in., or, 155 cu. in. per second per sq. in. This is a similar flow to what a paper filter would see, but my filter area is smaller. My filter appears to handle the flow fine even with its smaller area. Also, mine is a full depth filter about 1.2" thick instead of a surface filter like paper. Mine also has a more dense filter media than the sponge type high flow filters on the market, that's why I think I can get higher efficiency. The filter sees only a little dust at a time so trying to collect and examine what comes through can take as long as a year to get a good sample.

I'll try looking for background info to base my designs on at a university library as you suggest. I didn't think there would be much info on this subject so I came here for advice. What really hinders me is my lack of testing and measuring equipment. It seemss all I can do is take my best guess and try it out and hope it doesn't pass too much dust. Thanks.

 

[sciguyjim]

Well, I went to a nearby college to look for info and there was absolutely none. They, in turn, went online and looked in the country's largest database of library books and found only 2 entries! Niether one was helpful to me. It seems only a few companies are doing work of this type and they're keeping the info to themselves.

 

[Rich2001]

Contact Climet Instruments Co. at

http://www.climet.com/index.html

at one time they could supply you a huge amount of technical data on testing filters.

Look at the TSI site

http://www.tsi.com

for technical data and test reports.

My filter appears to handle the flow fine even with its smaller area. What is the pressure drop across the filter at this flow as compared to the others?

The filter sees only a little dust at a time so trying to collect and examine what comes through can take as long as a year to get a good sample. With the instruments by TSI or climet you can get a good data in a hour or so. Measyre the particle concentration upstream and downstream of the filter media. if you need to challenge the filter use Dispersed Oil Particulate (DOP light mineral oil) aerosol.

Try contacting F&J to get info on how they test their filer media.

http://www.fjspecialty.com/

REFERENCES

http://ateam.lbl.gov/Design-Guide/DGHtm/references.airfiltration.htm

 

[sciguyjim]

Thanks for the tips, I'll look up the sites you mentioned. Thanks