quote:Originally posted by Tim Vipond:
You still seem to be confused. The larger particles just sit on top of the nanofibers and still allows oil flow around it into the many pores available.
Filters design for water filters is similar to filter design for oil filters. We were talking about activated carbon in class one day and the applications and one of the various applications is making water filters. The Professor talked about surface treating the activated carbon matrix to create macro and then micro pores to allow particles (contaminants) to be trapped in this filter media. During the activation phase the surface of the carbon matrix forms a macro pore opening which goes into the matrix to taper off into a micro pore forming "cracks" on the surface of the matrix. So I asked the Prof what would happen if macro size particles keeps coming into the filter to block the opening and therefore stopping the micro size particles from getting trapped and he said in response that usually you have a multi-stage filtration system so that the macro size particles are trapped before exposing the flow to the micro filtration step.
From my last post I said that the Donaldson discontinued filter uses a multi-stage filtration process within one filter. This would mean that with the limited size available in the filter housing the filter needs to be able to trap larger particles first and then the smaller particles later.
Assuming that the web like design is uniform for the entire synthetic media the multi-stage filtration is then not possible as the large particles would start to clog the "nano" web forcing the filter to go into bypass mode. Large particles would large particles would first bombard the web and then subsequently particles of all sizes would start to find the path of least resistance until more large particles comes along to block up more of the nano webbing. Eventually medium size particles would start to form between large particles, so on and so forth, until the web is so inundated with particles that the filter is forced into bypass.
One way to counter this is to form a media that has cellulose sheath (outer surface) and a progressive nanoweb core (inner surface). This would allow large particles to be filtered before entering the nano web which then allows the nano web to do its advertised job of collecting nano-sized particles. The problem still exists in this case with large size particles filling up the sheath thereby blocking to flow as you move toward the center of the filter. Having a nano sheath and a cellulose core makes no sense so that scenario is thrown out.
Either way it doesn't seem like the nano-web can have a longer than average (25,000 vs claimed 3000 miles) drain interval when it has a fine net that is design to clog fast.
If you don't know please say so and ask the Amsoil engineer politely via e-mail. I know I've done it and I got bogus answers when I did but perhaps you can have better luck with them as you are still a dealer.