Twin primary fuel filter

[srah1953]

There was correspondence somewhere about the merits of twin primary fuel filter. ASAP have a Racor duplex unit for £700 whereas there is a Delphi twin unit on Ebay for £36. What am I missing?

 

[angelsson]

There was correspondence somewhere about the merits of twin primary fuel filter. ASAP have a Racor duplex unit for £700 whereas there is a Delphi twin unit on Ebay for £36. What am I missing?

I use a twin primary, also have a fuel polisher installed.

Twin filters are reasonably cheap, i use this company, no connection other than a satisfied user. Check their site.

http://www.ssldieselparts.co.uk/index.php

 

[pvb]

There was correspondence somewhere about the merits of twin primary fuel filter. ASAP have a Racor duplex unit for £700 whereas there is a Delphi twin unit on Ebay for £36. What am I missing?

What you're missing is that the two products you've mentioned aren't comparable! The Racor duplex unit at £700 is high capacity (227 litres/hour), about 5 times the capacity of the ordinary Delphi type filter! The Racor unit is pre-plumbed with changeover valve, etc.

The reason most people quote for preferring Racor is the ability to use spin-on filters. However, the Racor unit you've mentioned doesn't use spin-on filters. ASAP do list a lower capacity Racor duplex which uses spin-on filter cartridges - see here - and it's much more affordable.

You need to give some thought to why you want twin primaries. The main benefit is the ability to switch from a blocked filter to a new filter without having to stop the engine or bleed the system. If you want to be able to replace a filter element whilst underway, you need to give some thought to the valve arrangements, so that air can't be sucked in when you remove the old filter. And you need to give some thought to how you can bleed the new filter.

And as angelsson has helpfully pointed out, eBay isn't necessarily the cheapest place to buy filters.

 

[srah1953]

Thank you both for these. Is flow rate important? How do I know the minimum flow rate required for 39hp Yanmar?

 

[pvb]

Thank you both for these. Is flow rate important? How do I know the minimum flow rate required for 39hp Yanmar?

An ordinary Delphi/CAV type filter will do about 45 litres/hour, which is fine for your Yanmar.

 

[noelex]

There was correspondence somewhere about the merits of twin primary fuel filter. ASAP have a Racor duplex unit for £700 whereas there is a Delphi twin unit on Ebay for £36. What am I missing?

The Raycor units are much better, but their dual system is very expensive. You can make your own, for much less cost, with 2X Racor filters and some simple pluming.
The ability to change quickly is a useful safety feature. On my boat I simply use the generator fuel supply which can be changed instantly with a couple of valves to supply the main engine. I can also use it to top up the main engine primary filter with filtered generator fuel, so filter changes are easy.
I also have a polishing system. This is completely separate, but without a generator filter you might consider having the second filter double up as a polishing system.

 

[KellysEye]

If you have two inline filters and the engine filter then if one blocks the you won't know which one. We set up parallel filters, which motor boats have, with the appropriate on/off switches and ordinary Racor filters finer than the engine filter. Thus running one Racor and the engine filter if it blocks it's the Racor, simply switch to the other one when the revs start going up and down. Make sure to bleed both filters before startig the engine. It's very easy to do but takes a few hours.

 

[prv]

If you have two inline filters and the engine filter then if one blocks the you won't know which one. We set up parallel filters,

Um, yes, parallel changeover filters is exactly what this thread is about. Nobody is suggesting two in series.

Pete

 

[Jabamusic]

You need to give some thought to why you want twin primaries. The main benefit is the ability to switch from a blocked filter to a new filter without having to stop the engine or bleed the system. If you want to be able to replace a filter element whilst underway, you need to give some thought to the valve arrangements, so that air can't be sucked in when you remove the old filter. And you need to give some thought to how you can bleed the new filter.

Anybody any good with schematics to illustrate?

Jaba

 

[KellysEye]

No schematic but it's very simple:

Pipe from fuel tank to splitter. From the splitter one pipe each to the on/off switch screwed into the filter. One pipe each out of each filter to a spliiter (reversed as it were) and connected to the fuel pipe leading to the engine.

Everything needed can be bought from ASAP and they will need to know the size and thread of holes the hosetails/splitters screw into.

>Um, yes, parallel changeover filters is exactly what this thread is about. Nobody is suggesting two in series.

I've never heard of twin filters, I've only heard of parrallel, hence I mentioned inline in case the advice I was giving was on the wrong subject.

 

[vyv_cox]

No schematic but it's very simple:

Solent Boy kindly sent me a useful schematic which includes all the fitting descriptions and sizes ready to order from Aquafax or ASAP plus a few others. Try a PM to him.

 

[Jabamusic]

Thanks Vyv

Will do

Oh thks also to Kellyseye

 

[Ex-SolentBoy]

Thanks Vyv

Will do

Oh thks also to Kellyseye

I have had several requests for this diagram so I have converted it to a picture and attached it.

On of the great things about Rustler Yachts is they supply drawings like this for all the engineering. No mean feat as every boat is differently configured.

 

[rogerthebodger]

I have had several requests for this diagram so I have converted it to a picture and attached it.

On of the great things about Rustler Yachts is they supply drawings like this for all the engineering. No mean feat as every boat is differently configured.

Looking at your tank selection valve I have 3 tanks and this is the valve arrangement I made using a 3 way fuel valve one for supply and one for return.

I also used two 2 way versions of the same valve as a filter change over in a similar arrangement to your drawing but I don,t have a pic of that

 

[prv]

Pipe from fuel tank to splitter. From the splitter one pipe each to the on/off switch screwed into the filter. One pipe each out of each filter to a spliiter (reversed as it were) and connected to the fuel pipe leading to the engine.

Personally, I would (did) add a valve after the filters as well as before. This means that the filter being changed is completely isolated. With valves only on one side, you can't change a filter with the engine running (the lift pump will just suck air through the open housing instead) and I suspect it may also make bleeding slightly harder (because the open pipe can drain and will need to be refilled).

I also use changeover valves instead of pairs of on/offs, though obviously either will work.

Looking at your tank selection valve I have 3 tanks and this is the valve arrangement I made using a 3 way fuel valve one for supply and one for return.

I like that! Were the gears a standard accessory for the valves, or did you make up the mechanism?

Pete

 

[penfold]

On of the great things about Rustler Yachts is they supply drawings like this for all the engineering. No mean feat as every boat is differently configured.

They aren't doing it out of the kindness of their heart; the RCD requires them to include that kind of information in the otherwise pointless 'mighty folder of nonsense'. That said Rustler are the kind of builder who supplied that information to owners long before it was made mandatory by the eurocrats.

 

[rogerthebodger]

I like that! Were the gears a standard accessory for the valves, or did you make up the mechanism?

Pete

No. The gears are standard plastic ones from RS. I bored them out to fit the spindles and made the joining plate to suit the centres of the meshed gears.

 

[RivalRedwing]

The only downside with the 'Rustler' system is that you cannot run both filters simultaneously. Granted you don't want to for 99.5% of the time but if you were in a situation where first one filter part-blocked due to crud and then the second started to block before you got to safety you might well welcome the option to have both part-block filters passing diesel to the engine. Easily sorted by using ball valves and a T piece as opposed to three-way valves.
ASAP supplied me with a diagram to put a system together, helpfully annotated with their part numbers ;-).

 

[Ex-SolentBoy]

They aren't doing it out of the kindness of their heart; the RCD requires them to include that kind of information in the otherwise pointless 'mighty folder of nonsense'. That said Rustler are the kind of builder who supplied that information to owners long before it was made mandatory by the eurocrats.

Oh you cynic!

The RCD does seem to require a load of CYA obvious information (like WARNING: turn off the engine before working on it) , but believe me, the drawings I have go way beyond that requirement and include, for example, the component list, and supplier list to make replacement easier.

Rustler took the RCD document and then added a significant amount of really useful information to make it a proper "Owners Manual". I have things like a running rigging list, engine service checklist (specific to the boat and its components), engine performance data and internal storage listing. None of this RCD required.

 

[srah1953]

They aren't doing it out of the kindness of their heart; the RCD requires them to include that kind of information in the otherwise pointless 'mighty folder of nonsense'. That said Rustler are the kind of builder who supplied that information to owners long before it was made mandatory by the eurocrats.

Didn't get any diagrams that detailed with a recent jeanneau so must assume it's not an RCD requirement. There is the alternative that they just didn't bother ...