CAV's what brand of filter is the best ?

[mudski]

Yep not recommended for common rail motors, & unnecessary for cars that get their fuel in populated areas, but filtration is a bit better than 12 microns I think, at least according to this according to this.

screenshot_106.jpg

Mind you I have read claims they are as low as 2 microns elsewhere on the 'net (have my doubts about that though - I would think that may well affect fuel flow). My guess is that along with the variety of brands of filter that fit these CAV type housings there is probably a variation in micron ratings. Bottom line for me is that it works as per my previous photo & with no fuel flow issues using the stock GU fuel pump & no additional lift pump. That photo was after around 10,000kms. As a result I decided to change the CAV every 10,000 & the standard filter at 20,000, I'm yet to do that though. If I have the means to cut open the standard filter when I next change it I will, & if it looks clean enough may up the next change interval of the standard to 30,000kms.

They claim it to be 5 micron, but at what beta rating? It might be 5 micron at beta 2, which is 50% efficiency. Which means the filter will let 50% of particles at 5 micron or larger through. Some filters will have multiple ratings, 5 micron at beta 2, 10 micron at beta 10 (1 out of every 10 particles will pass through the filter) etc etc.
The beta ratings are as follows.

Beta Ratio. How Many Particles of a Given Size Will Pass
Through the Filter?----- Actual Filter Efficiency
2 ---1 out of every 2 particles 50%
10 ---1 out of every 10 particles 90%
20 ---1 out of every 20 particles 95%
75 ----1 out of every 75 particles 98.7%
100 ---1 out of every 100 particles 99%
200 ---1 out of every 200 particles 99.5%
1000 ---1 out of every 1000 particles 99.9%
2000 ---1 out of every 2000 particles 99.95%

So you can have a filter will 2 micron filtration but it has a really poor beta rating, which is just as important than micron rating. If the Delphi is 5 at beta 75 or better, then I would consider it a good filter.