RAcor filters - different micron options confuse me

Burnham Bob

Burnham Bob

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Apparently ...........Brown "S" is 2 Microns, Blue "T" is 10 Microns, Red "P" is 30 Microns.

ASAP suggest I need a 10 micron filter when I replace the CAV filter with a spin on. I'll take thier wqord for it but can anyone explain the difference? Is it the 'fineness' of the filter?
 
On our previous boat we had a 10 Micron Racor, and a 2 Micron on the engine itself. I also had a 30 Micron that I picked up as a spare once, and kept in reserve with the thought that it might be useful if I got a clogged up 10 and needed to get home. Not sure about the logic of that, never had to try it out.
 
thanks for the google advice earlybird, maybe I should have been more explicit - what I was hoping was that someone would advise me of the uses that 2, 10 and 30 micron filters were most suited to in the context of advice on boating use - ie this forum. if the flow rate is the same would a 2 micron filter be better for a preliminary fuel filter than a 10 micron? or would there be more risk of it blocking? obviously there is a secondary filter on the engine itself
 
The flow rates are the same. Most engines have a very fine filter mounted on the engine immediately before the pump. That filter will usually be of the 2 micron scale so 10 microns is normally regarded as the "standard" first filter. Having the filter sizes the other way round would be pointless.

Having said that, I don't think using 30 rather than 10 would be the road to hell - if I was given a load of free 30s and I didn't have a bug problem, I would use them.

Richard
 
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Filters are there to prevent muck reaching the injectors, damaging them and stopping the engine. Damaged injectors are expensive to have repaired.

Most engines will have a fuel filter on them (the fine filter) with a tolerance of 2 micron. If that's the recommended tolerance for the engine, it will only allow 'acceptable' muck through to the injectors that won't damage them.

Then before the fine filter you will have your CAV (the primary filter). This is much simpler to change and not on a hot engine.

I always use a 2 micron in the primary simply because it's easier to change than the fine filter, and if I'm in a horrid sea state, that's what I'd prefer to do. And it means I don't have to be close to a hot engine!

There should be no difference in flow rates between the different micron rated filters.
 
Piers said:
Filters are there to prevent muck reaching the injectors, damaging them and stopping the engine. Damaged injectors are expensive to have repaired.

Most engines will have a fuel filter on them (the fine filter) with a tolerance of 2 micron. If that's the recommended tolerance for the engine, it will only allow 'acceptable' muck through to the injectors that won't damage them.

Then before the fine filter you will have your CAV (the primary filter). This is much simpler to change and not on a hot engine.

I always use a 2 micron in the primary simply because it's easier to change than the fine filter, and if I'm in a horrid sea state, that's what I'd prefer to do. And it means I don't have to be close to a hot engine!

There should be no difference in flow rates between the different micron rated filters.
Click to expand...

That method simply means that the engine filters will not be doing any filtering, as previously said stage filtering is the normal method.
 
I have a settling trap, a 20micron Racor filter, and a 2 micron filter on the engine.
In 2000 hours, on the new engine, I've never had to change the Rotax element, all the muck being trapped at the settling trap, though the engine element has been changed every 350 hrs - the element has only been slightly discoloured (iron oxide) on one occasion.
All the blockages (3 in 25 years) I've had have been in the pick-up pipe in the tank. When that occurs I take out the tank and steam-clean it.
Theory and practice frequently diverge.
 
Piers said:
Think of it this way. Which filter would you prefer to clog. The primary (CAV) or the fine (the engine)?
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I'm not an expert Piers and if you are I'm happy to bow to your knowledge ...... but I don't think that is the whole story.

The point of using a progressive filtering system, which is the norm in industrial manufacturing applications, is that you increase the probability that the engine will continue to run even if a lot of muck is coming from the tank. Obtaining maximum running time could be important if you are in a critical situation. You lose that advantage if your first filter is 2 micron as there is a much higher chance of it blocking sooner and that might be at a time when trying to change either filter is very difficult.

I think that I once saw a mathematical proof of the benefits of progressive filtering.

Richard
 
RichardS said:
I'm not an expert Piers and if you are I'm happy to bow to your knowledge ...... but I don't think that is the whole story.

The point of using a progressive filtering system, which is the norm in industrial manufacturing applications, is that you increase the probability that the engine will continue to run even if a lot of muck is coming from the tank. Obtaining maximum running time could be important if you are in a critical situation. You lose that advantage if your first filter is 2 micron as there is a much higher chance of it blocking sooner and that might be at a time when trying to change either filter is very difficult.

I think that I once saw a mathematical proof of the benefits of progressive filtering.

Richard
Click to expand...

You are absolutely right. I suspect you would get a longer run time. I just hate the thought of anything getting anywhere near the engine given the potential cost of injector repair etc. I used to run 10 micron filters in the Racors and 2 micron in the fine filter until I talked with the Racor Sales Director. He said to use 2 micron in the primary and that it wouldn't effect the flow rate. He went on to add that even better would be to have two primaries - one at 10 and the other at 2 !

Thankfully, I've never suffered a problem in Play d'eau.
 
+1. For the same reasons I reduced our Racor filter from 10 µm to 2 µm. Added to which the Racor filters were about a quarter of the price of the Yanmar filter on the engine.
 
Burnham Bob said:
Apparently ...........Brown "S" is 2 Microns, Blue "T" is 10 Microns, Red "P" is 30 Microns.

ASAP suggest I need a 10 micron filter when I replace the CAV filter with a spin on. I'll take thier wqord for it but can anyone explain the difference? Is it the 'fineness' of the filter?
Click to expand...

Apparently the CAV filters are a 4 micron, or at least the Delphie replacement cartridges are. I've heard that from two independent sources now.
 
The set up on my engine is two parallel Racor filters as primaries with 30 micron elements, and the normal spin on filter on the engine, which will be 2 micron.
Never had any problem with it. It was installed from new by Rival Bowman, who I trust knew what they were doing, for a very thorough and fussy owner who cruised extensively and did not see the need to alter anything in eleven years. 30 micron is what my Yanmar dealer also advises as the primary filter.
 
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