whats the difference between single and multi pass oil filters? from what i see on the market, advertised on oil fitler boxes, the better oil filters, are all multi pass. only real filter i ever see advertising single pass is fram. single would mean, catching paritcles first pass throug filter. mullti meaning eventually the filter will get it? at what micorns, do multi pass usualy get? and single?
difference between single and multi pass filters?
- Thread starter ziggy
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It's referring to the test that they're citing to quote the performance specs. All filters are tested under single and multipass tests. They can manipulate either to look good. The one that shows the best results is the one that they advertise on the box.
It's sorta along the lines of a friend of yours telling you: My next door neighbor OWNS A SHOPPING MALL (slight pause and then said quickly and in fine print) with other interests..
That is, it's only part of the story.
Mel can give you the full story on what filter manufacturers mean when they cite one test over another.
It's sorta along the lines of a friend of yours telling you: My next door neighbor OWNS A SHOPPING MALL (slight pause and then said quickly and in fine print) with other interests..
That is, it's only part of the story.
Mel can give you the full story on what filter manufacturers mean when they cite one test over another.
Single pass is a simple test where the lab takes a section of media and passes contaminant in fluid through it. The media is weighed before the test, contaminant is "weighed", and then after the test, the media is weighed again.
The results give you a "weighted average efficiency" by determining the amount--by weight-- of what the section of the media didn't trap in one pass.
The contaminant particles have a certified count before the test by size.
As for multi pass..
Read this:
http://www.filtercouncil.org/techdata/tsbs/89-5R3.pdf
The difference is: Single pass is conducted on a sample of the media. Multi-Pass is conducted on the finished filter.
The results give you a "weighted average efficiency" by determining the amount--by weight-- of what the section of the media didn't trap in one pass.
The contaminant particles have a certified count before the test by size.
As for multi pass..
Read this:
http://www.filtercouncil.org/techdata/tsbs/89-5R3.pdf
The difference is: Single pass is conducted on a sample of the media. Multi-Pass is conducted on the finished filter.
So is the single pass not as accurate as the multi pass? Some filters only state the single pass, so I wonder if its because they suck?
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Probably because it gives them the best performance figure to advertise.
Well, the multipass test costs a lot more money to perform too.
FG, who is usually right on the money, is off just a little on the single pass explanation.
A single pass test gives the filter one chance to catch contaminant. The test contaminanat is usually round glass beads (spheres) that can be purchases in about any cut you want to use. 10 to 20 micron are used a lot but years ago some customers specified as high as 10 to 70. The contaminant is placed in a swirl chamber that is isolated from the main flow circuit.
Clean test fluid is circulated through the filter, valves are moved and all of the beads go swooshing their way toward the filter. What beads the filter misses are caught by a woven metal mesh filter downstream. The beads are weighed before and after and the efficiency is calculated. It's a straight efficiency. Weighted average means "time weighted average" and is used when multiple samples are taken over given time intervals. This is not the case with single pass testing.
As Mel said it can be used with a sample of filter media only but most automotive oil filters are tested as an assembly. The media only test is most common in the hydraulic industry.
A single pass test gives the filter one chance to catch contaminant. The test contaminanat is usually round glass beads (spheres) that can be purchases in about any cut you want to use. 10 to 20 micron are used a lot but years ago some customers specified as high as 10 to 70. The contaminant is placed in a swirl chamber that is isolated from the main flow circuit.
Clean test fluid is circulated through the filter, valves are moved and all of the beads go swooshing their way toward the filter. What beads the filter misses are caught by a woven metal mesh filter downstream. The beads are weighed before and after and the efficiency is calculated. It's a straight efficiency. Weighted average means "time weighted average" and is used when multiple samples are taken over given time intervals. This is not the case with single pass testing.
As Mel said it can be used with a sample of filter media only but most automotive oil filters are tested as an assembly. The media only test is most common in the hydraulic industry.
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