Water separator/diesel filter

wooslehunter

wooslehunter

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I only have a filter mounted on the engine (Watermota) & am thinking I should fit a water separator/diesel filter up stream bwteen the tank & the motor.

Any ideas on a good source?
 
ASAP Supplies have a good range of filters, but a lousy website! If you search for 302003, it's a filter/separator like this...
302003.jpg
 
Don't see what you have against their website, but anyway if you go to it you will see a series of clicky boxes on the left. Click on "Fuel Systems" then "Racor fuel filtration products" and you will see a filter numbered 301501.
The performance of these is far superior to the CAV type you showed. It includes a turbine and water block filter and will take out everything from bricks to fine particles, water, bio-crap and just about anything you might find in diesel.
The filter elements in the CAV filter are OK at removing a certain amount of water but soon degrade if they get very wet. Also the pressure drop across the filter will rise very quickly with a CAV type where racor tends to shed the water to the bowl more efficiently and being made of waterproof media do not degrade so fast. Also changing a filter element is easy and not messy. Changing a CAV (especially at sea) is a nightmare. They are twice the price but I heartily recommend them.
By the way, if you think I have a vested interest I don't. In fact I served my time with CAV so just the opposite!
 
Yes, the Racor is a fine filter, but it should be for £140! As you know, the model you specified is rated for 227 litres/hr max flow, which is about 50 times more than the original poster's engine is likely to take. At such low flow rates, any "turbine" separation action is severely reduced.

If the original poster wants to go for a Racor, I'd have thought the smaller 120 series would be a better choice, although still expensive. On this side of the Atlantic, Racor filter elements are not always easy to find, so it's worth keeping a stock on board. (The CAV-type elements seem to be universally available).
 
The only problem I have had with the CAV is overtightening - I have cracked two glass bowls this way.

I always carry a spare glass bowl, just in case.

John
 
Absolutely not the case. The rate you mention is the MAXIMUM flow rate. I have two fitted to my own boat and they work superbly well. The turbine reaches a maximum effective speed at very low flow rates and is stated by Racor themselves to be more efficent at low flow rates than it is at the higher end of the capacity range. If you don't believe me e-mail their technical department and they will confirm it. The flow rate of the CAV is significantly lower for the very reason I stated. The filter itself has a very limited capacity. That means the PD goes up very rapidly as the filter becomes contaminated. Apart from the previously stated "aquabloc" characteristics that the CAV simply doesn't have, a filter that has large effective area and high maximum flow rate is bound to be more efficient. This is one area where the bigger the better. As you say the smaller, non turbine types are available but very little cheaper. As far as replacement elements are concerned I know of 3 stockists local to me apart from ASAP and as far as having spares on board, everyone should have these anyway. As far as expense is concerned, a filter is a very cheap item when compared with a knackered fuel pump or worse. Buying cheap and saving pennies is never a good philosophy.
 
That is indeed one problem. Undertightening can cause poor sealing too especially if the head has already been distorted by overtightening as they can be. However I did not mean to imply that CAV are rubbish. For many years now they have been an industry standard and if the element is changed regularly and properly tightened it should work OK and give good service.
I used to get called out regularly to problems with diesel engines on boats though and by far the most common source of problems was always dirty fuel, blocked filters or leaks (many of them at the filter itself due to distorted or mangled filter heads). A filter that costs more is going to be unpopular I guess but the extra is no more than an extra tin of antifoul as a one off cost. Put that in perspective against the fact that the Racor will last a lot longer, hold more contamination, stop water without damaging the element, and can be changed without dumping half a pint of diesel in the bilge and having to bleed down the whole system afterwards and I think it's no comparison.
 
I had the same problem, (only one filter and no water seperator) added the one in Pvb's picture, it has done the job brilliantly, the one I got comes with a pump built on top to help with bleeding.........the cost £5 poonds, took mine from an escort van at the local scrap yard.
 
The problem with the CAV is that you have to be a Zen Master to get the O rings to fit.

I got so fed up struggling with them I fitted a Racor.
 
Here is what ASAP supplies themselves say on their website

CAV type filters are inexpensive filter units. For years they were standard fitment in boats, vehicles and plant. Recently, with the development of other products such as Racor, the low price of the units has become less important, as owners realise that there are more efficient filter/water separators on the market.
Replacement elements are inexpensive and widely available. Although still a popular choice it should be noted that any water separated out by these units is retained on the CLEAN side of the filter, and that the elements themselves are not waterproof

They sell both Racor and CAV. Interestingly even if you already have a CAV type they sell an adaptor kit to convert it to a Racor "spin on" filter. Not as good as the turbine type but if you want a cheap solution I am told they sell a lot of them. I wonder why? /forums/images/graemlins/smile.gif
 
[ QUOTE ]
.... they sell an adaptor kit to convert it to a Racor "spin on" filter.

[/ QUOTE ]

I shall order one tonight.

Some advice, please. Should I go for the 2micron or a larger element. Fuel is clean, and the engine is only a small 20hp (Buhk) taking about 5lt per hour.

thanks
John
 
There is always a guy at the Beaulieu boat jumble who has a whole stand selling nothing but CAV filters and elements
I always stock up there, he sells at a fraction of the regular price
 
For primary filtration (you have secondary fine filter on your engine anyway) 10 micron is plenty fine enough for diesel.
If you wanted to be ultra fussy 5 micron but you will need to change it more often and the secondary filter is there for that anyway. What you are trying to stop in primary filtration is larger particles, water, and sludge from your tank.
If you are ultra fussy (like me!) the ultimate is to have a secondary "polishing" circuit. I have two tanks. One is a "day" tank and the other a "bulk" tank. There is a completely seperate circuit out of the bottom of my bulk tank, through a large Racor and back into the top. Whenever I fill up the bulk tank I run this circuit for about an hour to clean up the tank contents before allowing it into the day tank.... But I am paranoid! The filter on that circuit is 10 micron and the primary on the exit of the day tank 5 micron. Generally the 10 micron filter catches the majority of the crud and the 5 micron one gets very little. I don't really suggest you go that far. Just fit a 10 micron "aquablock" and check it regularly.
Edit.... The standard 296 CAV is in fact 5 micron. If you really do want like for like it would be 5. I would still think 10 OK though if you have a secondary filter before the pump. Your choice!
 
I've always thought that the filter shown is rigged backwards, the crap sits on top of the element when it should be in the base. (Could it be run backwards? The muck would drop off the bottom of the element.) Also, if you do get muck in the bottom it sits on the glass, and does not get to the drain plug in the base. You have to dismantle it to clean the glass, the rubber seals don't fit second time round, plus the chance of broken glass. I badgered the local engineer and he got me a plain transparent plastic bowl separator, it is tapered down to a drain plug at the bottom, so I let the muck go every day if necessary. The head is the same as the CAV shown, it must be one of theirs.
 
You say " 2 micron" without any explanation of why and I think you need to justify that statement.
The final filter on any diesel engine will indeed be 2 micron already. All you will do if you fit another 2 micron filter before it is to make the final filter redundant and cause a higher PD across the primary filter more quickly (especially if there is water present) Racor filters elements are available in 30,10,5 and 2 micron. Why do you think that is?
30 micron is used only as primary filtration on contaminated fuel, usually on delivery systems. 10micron is ideal for removal of the worst particulate contaminates and water seperation on board. 5 is normally thought of as an intermediate grade and as I said, used extensively on CAV systems where this is the only primary filter. There is an argument that 5 is standard application for marine use therefore, where there is a 2 micron filter downstream of it. Having used a 10 micron filter upstream of a 5 with a final filter being 2 for some time and used fuel from the UK, France, CI, and Ireland, I can tell you that the 10 micron takes out water (sometimes a lot of it) biological sludge, and a lot of other stuff. The 5 micron down stream which has a pressure differential gauge on it lasts a very long time, and the 2 micron filter on the engine is only routinely changed every 2 years and frankly seldom needs it. I think that indicates to me that a 10 micron does the main job required, but a 5 could be argued to be even better if it is all you have and changed regularly. There is absolutely no justification for having 2 filters of the same rating downstream of one another however, and a 2 micron primary filter will only block more quickly, especially with water and bio sludge.
 
Hi Boatmike,

This 'discussion' has been the subject of much debate in the magazine Passage Maker (States) for the last year or so, with many articles by the Technical Editor. A thread on the forum is HERE.

Does this help explain the reasoning? You will see from the thread that at least one boat manufacturer has started the change to 2 micron (and maybe others but I haven't asked or searched). And if the SD of Racor advises the same, I'm happy to go with that.
 
[ QUOTE ]
You say " 2 micron" without any explanation of why and I think you need to justify that statement.
The final filter on any diesel engine will indeed be 2 micron already. All you will do if you fit another 2 micron filter before it is to make the final filter redundant and cause a higher PD across the primary filter more quickly (especially if there is water present) Racor filters elements are available in 30,10,5 and 2 micron. Why do you think that is?
30 micron is used only as primary filtration on contaminated fuel, usually on delivery systems. 10micron is ideal for removal of the worst particulate contaminates and water seperation on board. 5 is normally thought of as an intermediate grade and as I said, used extensively on CAV systems where this is the only primary filter. There is an argument that 5 is standard application for marine use therefore, where there is a 2 micron filter downstream of it. Having used a 10 micron filter upstream of a 5 with a final filter being 2 for some time and used fuel from the UK, France, CI, and Ireland, I can tell you that the 10 micron takes out water (sometimes a lot of it) biological sludge, and a lot of other stuff. The 5 micron down stream which has a pressure differential gauge on it lasts a very long time, and the 2 micron filter on the engine is only routinely changed every 2 years and frankly seldom needs it. I think that indicates to me that a 10 micron does the main job required, but a 5 could be argued to be even better if it is all you have and changed regularly. There is absolutely no justification for having 2 filters of the same rating downstream of one another however, and a 2 micron primary filter will only block more quickly, especially with water and bio sludge.

[/ QUOTE ]Good explanation. As you use Racor filters, can you say where you buy your 5 micron elements? Only asking because Racor don't seem to make any.
 
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