I agree Nick— You're right, certainly about the industry norm. And I’m sure there are many theories on this: and mine may be incorrect. But the way I think of it: Crud exists in a myriad of sizes. Crud forms… then gets into the filter system and clogs. If i have a series of sequentially smaller sized filters, i simply clog them all. and then replace them all. If a bolus of crud makes it into the sequential filtering setup: filters essentially sort the crud into smaller sizes at a great cost (especially with the last Volvo filter now being fouled). So we've cruised with the 2 micron setup for about 500 hours of motoring from panama to NZ last year and it seemed to work well. no issues. Filters seemed pretty good looking when i changed them Usually around 100 hrs, (I previously was quite derelict about it, prior to really understanding how important clean fuel was.) I have noticed the manometer pressure reading on the setup would climb slightly over the 100 hrs, but never concerningly high.
So scenario above A, with ostensibly clean fuel, worked for us, for this while.
So… Scenario B: Cruddy fuel shows up. A slosh of crud makes it into the filter setup. (is this an isolated bit of crud, or does it advertize a yet much larger crub problem in the tank) Currently it would saturate the 2 micron first filter and pressures climb, engine shuts down alerting us to a pressure scenario and we change filter: but now we know we have cruddy fuel and need to polish it and the tank. (and why I’d like a separate fuel polishing system on board.) Heres where my scenario breaks down: it depends on the amount of crud: pump it out and through baja filter into jerry cans? then run engine off jerry cans? or...( I do have a bunch of 10mn and 30mn sizes as well) as well put those on and let the filters clean the crud out: but if I increase the racor size then ill be clogging my 130$ volvo filters very fast: i carry about 4 of those, They're proprietary and hard to get in places. It turns into a "S" show.
So what's governed our cruising: sail smart, with wind as much as possible so we motor little. Praise our relatively large 900 litre tank, and the freedom it adds to be discriminate about fuel choice. When others are fueling out of necessity, i find myself adding fuel not because i think we're low, but… hey were sailors and should keep topped up stores.
I'd be surprised if I’d completely thought this through, I'm sure there are some folks who really understand this at a much deeper level and I would love to hear from them and you.
And as you note Nick, it is the industry norm, and usually there is good reason for that! To that end, if the Volvo-proprietary “C” filters were as inexpensive as the racors—I’d also stick to industry norm.
I’d respectfully welcome any thinking and guidance.
Porter A54-154 with a “H” model D3-110
On Feb 9, 2020, at 10:42 AM, ngtnewington Newington via Groups.Io <ngtnewington@...
Hi Scott and Porter,
I choose to use a 10 or even 30 micron filter on the Racor followed by the Volvo secondary filter which is 2 micron I believe.
In my opinion by having the pre-filter at 2 micron you are in effect only having one filter. So in the event of major contamination the Racor will plug and the engine will suffer from fuel starvation. You may also damage the fuel pump, although on the 54 the fuel is gravity fed from the tank to the filters.
The same principle applies to the water maker. There is a course filter followed by the fine filter. You can not just go straight to the fine.
I know this is a controversial subject but that is my opinion….and the industry norm.
Amelia AML 54-019
I understand. We have the same setup. The dual racor (A vs B) and A+B if one wishes. We keep the 2 micron on both A and B and use only A or B, switching back and forth. Filter C is of course the very pricey Volvo-specific filter/fuel water separator, which is what I want to spare by using the 2 micron. I watch the pressure gauge on the racors a lot. That’s why we change frequently, to keep pressures low. We have no pre-pre filters.
I remember a thread on this about a year ago, the 2 micron pre-filter argument. That’s when we switched. Its hard to be scientific when we have limited data re what works “best.”
Great comments on why to keep the tank full during storage.
I have the two racor filter setup. I consider this the primary filter / pre-filter.
1) FilterA only
2) FilterB only
3) FilterA and FilterB in parallel
Do you run the 2 micron filters here?
On my D3-110C there's a Volvo spin-on filter (2 micron) on the engine itself. We'll call that FilterC
Did you install a pre-filter before the Racors??
2007 A54 #69