Mr Mower Man wrote:Can anyone explain to me how an aftermarket fuel filter can claim to be a replacement for an OEM filter when the micron ratings don't match? Take the Briggs & Stratton 691035 filter, for instance. It has a 40 micron rating. The Stens aftermarket replacement (120-562) is rated at 30 microns, Rotary's (7998) is rated at 60 microns, and Oregon's (07-107) is rated at 80 microns. Am I really using an aftermarket equivalent with one of these filters? Or does it really not even matter?
Furthermore, is a paper filter with a 75 micron rating any more or less effective than a screen filter with the same micron rating (like the Briggs & Stratton 394358S)? It seems to me that a paper filter would be superior to a screen filter, though I don't really have any data to back that up. Or, again, does it really not matter?
Thanks
Micron rating is just that - the smallest particle , measured in microns (A micron is a unit of length equal to one millionth of a meter) that will pass through the filter media.
So a 60 microns filter will block particles that would pass through a 75 micron filter - media does not matter whether it be screen or paper - micron rating will be the difference. Many of the aftermarket parts do not have a guaranteed micron rating - they will often be typographical errors, or they are "certified" by the manufacturer (from china) and the vendor just takes the manufacturer's word for it - manufacturing changes may result in different micron ratings but the brand may be using an old rating from a different supplier.. lots of variables.
Considering this: 40 microns is 0.001575 inches 60 microns is 0.00236 inches , 75 microns is 0.00295 inches and 150 microns is 0.00590 inches
Do you think you could even SEE a piece of dirt that is .0015" diameter suspended in a gallon of gas?
Micron ratings are specified so that any debris that does manage to pass through won't clog the smallest port or jet in the fuel system - if you put in a 75 micron filter where a 60 micron is specified, eventually you'll end up with a clogged carburetor. At the same time, a smaller micron rating can also affect fuel flow (read: gravity feed carburetors) so putting a finer micron rating filter in a system where a coarser rating is specified can affect fuel flow in the system.
So, we'll use OEM product wherever we can but if we have to put in an aftermarket filter somewhere, we'll use something that is at least close to the original rating, if we have any specification available, failing that we'll put in a filter between 60-75 microns
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)