In my experience, WVO at room temperature does not readily pass through fine filters, even if it is largely free of particulate matter, so your problem is not necessarily being caused by filter clogging. Having said that, my filters sometimes seem to clog with goopy animal fat like material (aka “milkshake”). (I try to gravity settle that stuff out before the filter to the largest degree possible). Also, IMO, 100 gallons is a lot to pass through one set of filters. I would say that I often have to change out/ clean the filter after 50 gallons or so.
My recommendations would include:
1. Yes, install the pressure guages- they allow you to monitor the curve of performance of your filters, as well as hopefully helping you to avoid an injury!
2. Settle as much stuff out of your oil in advance of filtering, both particulate matter and white sludgy stuff will readily clog your filters.
3. Set up your system in such as way as you can set a batch to filter, and then go away while it is working… If you expect to set up a system where you can filter 100 gallons in 3 minutes,… you are setting the bar pretty high for yourself.
4. One more thing: there is a pretty big disparity between the oil from one restaurant to the next. And there is also a disparity between oil from the top of the dumpster to the bottom, especially if it has been sitting in the sun, and has separated into layers. As you collect, be aware of what you are getting!
I date each jug I collect, and I only collect from one restaurant. I try to let each jug set for at least 3-4 weeks before carefully pouring it into my set-up so as to avoid disrupting the cake that has formed on the bottom and to avoid the heavy fats that settle down. Once I get close to the “milkshake” I stop pouring and will pour the remaining oil into a spare jug that I use for that purpose to allow it to resettle and then I get the collective remaining good oil from the remains of 5-6 jugs once it has settled. The way my system is setup now, it was filtering about 4 gallons in 5 minutes. So far, I have picked up a furnace but have been too busy to do anything with it. I have started with a filter system, and now am trying to work the bugs out and improve it. I figure the approx. 1 gpm filtering rate was a nice rate to try for. I am going to hook up pressure guages when I get a chance. I still haven’t had a chance to order a new filter for it.