Air Filters - Micron Ratings

Since this thread, http://www.arboristsite.com/showthread.php?t=64861 , doesn't appear to be bearing any fruit, I guess I'll have to rebuild my Jonsered 920 air filter.

What is the micron rating of the typical chainsaw air filter?

I've found some likely filter materials at mcmaster-carr.com. Using polyester felt I can get down to 5 microns however, I don't want to sacrifice flow. How low should I go?

Talking to myself...

They say the Lord helps those who help themselves.

Here's what I've found in response to my own questions re:air filters.

1. Air filters are typically not given micron ratings. Micron ratings are used for liquids.

2. I cant find much of anything in the way objective information about how fine an air filter needs to filter. I can find some numbers quoted by Amsoil on the super duper car air filters, numbers in the 10 micron range.

3. I have found info re: fuel filter micron ratings. The lowest number I find for chainsaw fuel filters was 40 microns. Many only filter down to the 100-150 micron range.

4. Since the air and fuel end up in the same combustion chamber I have concluded that the air and fuel filters should filter to about the same degree.

To that end and unless one of you more experienced and knowledgeable folks tell me otherwise, I plan on doing the following:

1. remove the screen/flocked parts of my filter.

2. sand or grind smooth the top and bottom surface.

3. glue on stainless steel ultrafine wire mesh to the top and bottom of the filter. this stuff will filter down to 60 microns.

4. place one or more layers of polyester filter felt (25 microns) inside filter.

Even if I find that the 25 micron felt is too restrictive I can remove it and still be left with a 60 micron air filter.

You got a better idea?

www.mcmaster.com
Look at page 391, some of this and some hot glue or super glue should work. There is a page that describes micron, it go as fine as talcom power.

Thanks Clint,

The materials I decided on are p/n: 6376t14 on page 376 and p/n:92715t27 on page 383.

I'm not sure which of the products you're referring to on page 391 'cause there are so many. I'm sure there are lot's of different kinds of filter media that would work.

I don't know if you're familiar with the filter on the 920 but it's basically a shallow plastic box about 1/4" deep by maybe 4" wide x 4" long. The top and bottom of the box are made up of a plastic screen that has flocking spread over it. The interior of the box is empty.

I want to replace the flocked top and bottom with the stainless mesh and put the poly felt inside the box. That'll give me the option of switching out the inner filter to a finer or courser grade depending on my results. I may also go with no inner filter if I think the 60 micron outer filter is enough.

I'll tke photos and if this works I'll post them.

Micron is pretty small.

1/1,000,000 of a meter.

1/1000 of a milimeter.

.000039 inch

http://en.wikipedia.org/wiki/Micrometre

bogiemsn said:

They say the Lord helps those who help themselves.

Here's what I've found in response to my own questions re:air filters.

1. Air filters are typically not given micron ratings. Micron ratings are used for liquids.

2. I cant find much of anything in the way objective information about how fine an air filter needs to filter. I can find some numbers quoted by Amsoil on the super duper car air filters, numbers in the 10 micron range.

3. I have found info re: fuel filter micron ratings. The lowest number I find for chainsaw fuel filters was 40 microns. Many only filter down to the 100-150 micron range.

4. Since the air and fuel end up in the same combustion chamber I have concluded that the air and fuel filters should filter to about the same degree.

To that end and unless one of you more experienced and knowledgeable folks tell me otherwise, I plan on doing the following:

1. remove the screen/flocked parts of my filter.

2. sand or grind smooth the top and bottom surface.

3. glue on stainless steel ultrafine wire mesh to the top and bottom of the filter. this stuff will filter down to 60 microns.

4. place one or more layers of polyester filter felt (25 microns) inside filter.

Even if I find that the 25 micron felt is too restrictive I can remove it and still be left with a 60 micron air filter.

You got a better idea?

Click to expand...

Give this some thought, clean the screen/flocked parts of your filter. Use a oiled foam air filter inside. Check your private message for another option.