Rich H.
I Googled your wording on the make up of the filter media and got mostly medical type filters. I have a Raycor 220 spin -on primary with 10 mu Raycor R24T element (which I thought was also a water separator) and the standard Yanmar secondary on the engine with presumably 2mu paper element on a Yanmar 2GM20F.
Neither filter ever seems to have any dirt and absolutely no water since I installed an acess port to the Poly fuel tank and cleaned it completely, plus replaced all the fuel lines. Are you saying that the Raycor filtyer media will absorb water and breakdown? What, if anything would be visible in the Yanmar secondary filter if that were to occur?
Yup, ......
The filter media for most diesel fuel applications, including Racor, is a microfiber cellulose which is encapsulated with an epoxy - essentially a 'technical' paper. The resination process is not perfect and there will always be exposed or non-encapsulated fibers that absorb water; water will digest the exposed fibers ... such filters typically will last 1 year in service. Once the fibers become saturated with water and after 'digestion' of the cellulose, they become quite weakened and the filter media becomes 'soft' and unable to withstand (much) differential pressure across the pleats; and, either you get pleat rupture or 'breakthrough'. You have to remember as a filter begins to 'choke' with debris that the differential pressure across the filter media will quickly rise and if the differential pressure is greater than what the now weakened strength of the water saturated / digested filter media = 'blowout', pleat failure, etc.
Where is the water if I dont see it? The water is in molecular (direct absorption from the atmosphere ... you have an atmospheric vent on your tank, you HAVE water whether you can see it or not) or macromolecular/emulsified water (water that is 'chopped up' due to pumping, etc); both species of water forms will between the molecules of the oil. Only when there is enough water to SATURATE the mixture and begins to settle out by gravity will you be able to SEE it.
There is essentially only one monopoly world supplier for this technical paper. All these technical paper filters are 'nominally' rated. Racors are nominally rated to about ~97% (weight) capture efficiency at their 'rated' µM, meaning that under idealized conditions they will capture ~97% (wgt.) of the particles at that 'rating'. However it also means that there is a potential that such rated filters can occasionally pass a basketball if the weight percent of that basketball is less than the total !!!!!
The accepted 'most damaging' particle in a diesel engine is 20µM; using a 10µM, 97% removal efficiency or 'nominally rated' filter will tend to ensure that 20µM particles will be at a statistical 'minimum'.
The typical recommendation for 'most' diesel service is: tank --->30µM ---> 10µM ----> (15-17µM engine mounted GUARD filter) ---> injector pump, etc.
The 30µM is a 'prefilter' to the 10µM and is there to extend the service life and to 'protect' the MAIN STAGE 10µM .... and if 'operational history' deems it necessary to extend the service life of the 10µM. If youre running a clean system, clean the tank occasionally, obtain your fuel from a 'reliable' source, then there probably is no need for the 30µM .... but your gages have already told you that !!!!! If youre operating in 3rd world where sand, 'gunk', rocks, sticks and feathers are common in the diesel oil, then definitely you need the 30µM.
The 15-17µM
small engine mounted 'guard' filter is there principally to ensure that if an upstream filter has a breakthrough or rupture etc., or that soft particles start EXTRUDING THROUGH the 10µM stage that this filter will quickly 'choke' and shut down the entire system ... consider the engine mounted filter as a FUSE,
only ... its a LAST CHANCE FILTER, like a FUSE. Since it has
small surface area, and the relative higher velocity through the 'guard' filter will drive debris deeply into the filter media and 'quickly' shut down the flow and prevent engine and injector pump damage.
FAQ - Why not use a 2µM rated filter?
..... for several reasons:
1. a 2µM filter will have 5 times the operating differential pressure drop across it than a 10µM to deliver the exact same amount of oil. Your typical engine lift pump can only 'suck' to about 5" hg vacuum and if you 'burn up' all that motive pressure in forcing the oil oil through a 'tight' filter .... youre not going to have much 'reserve' vacuum to deliver oil.
1a. Expect premature lift pump diaphragm failure when running a 2µM ... it takes WORK to run these filters!!!!!
2. Also there are exponentially more particles in nature the smaller in size you go - a 2µM will 'plug' much faster than a 10µM, about 10-12 times
FASTER.
3. Most "normal" particles in diesel fuel system are soft/deformable particles: .... dead microoganism debris and their products of metabolism. The 'tighter' the µM rating, the higher the differential pressure across the filter medium with higher the velocity 'through' the filter media .... all which can lead to the EXTRUSION of soft/deformables right through the filters. These extruded soft/deformables dont 'burn' very well in the combustion chambers and 'settle out downstream in the hot exhaust system - coke! Think of that next time you have to clean out an exhaust system or injection elbow.
Of course sand, iron/rust is easily removed by the 'prefilter stages'.
FAQ - My filters dont LOOK dirty so why should I change them?
Because the size range of particles that the 10µM captured particles needs a high power microscope to visualize, they arent directly visible to the naked eye (the smallest particle that you can see with the naked eyeball is about 40+µM and with the correct lighting conditions) AND these particles are not captured ON the filter but deep INSIDE the filter media, usually in the first 15% of 'depth'.
The ONLY way you can tell if your filter is still capturing particles or is near 'choked' is with a pressure/vacuum gage ..... you occasionally run the engine at WOT to see if there is 'reserve' vacuum (pressure) for the filters to operate ... and you RECORD the vacuum/pressure gage numbers each time you check so that you can 'predict' when such failure occurs.
If you are monitoring vacuum/pressure gages (vs. WOT) and you have 'real old' filters and you denote a sudden
DROP of operating vacuum/pressure - that denotes a BREAKTHROUGH or a pleat failure/rupture and you'd better start changing filters because the 'next' filter in series is soon going to get an 'overload' ...... that's the only way you can successfully run such filters for BEYOND the yearly changeout recommendations - gages !!!!!!!!!
If you leave such filters in service for 'years', you dont ever clean out your tankage, you dont monitor the filter operation with gages so you REALLY know if or when to change ..... Id think youre blindly risking for a new/rebuilt injector pump or injectors in place of the cost of $20-30 ea. for a new filter(s). Such rarely happens; but, it 'does' happen.
Note: most engine manufacturers SPECIFY the exact size retention of the filters ... All this is based on historical operating data from the past ~80 years by the SAE, etc. folks. If your engine filters are NOT otherwise specified by the manufacturer; then, tank --->30µM ---> 10µM ----> (~15-17µM engine mounted GUARD filter) ---> injector pump, etc.
hope this helps.
Do get some gages onto your fuel line filters so you know WHEN to change them.
). During that time we put more that 1200 hours on the engine without any fuel issues what so ever.
