Fuel polishing

[dehler25]

I am putting a permanently mounted fuel polisher together with a Racor 500 FG as the filtering element, I intend to tap into the generator fuel lines feed and return and divert to the polisher when desired. The question I am tussling with is whether to insert ball valves or check valves on the generator and polisher lines so they never interfere with each other. Seems simple and straight forward, but is one way superior to the other. Several options are available for the valves and it seems that the check valves would flow or block without any action. Simply powering up the polisher pump would move fuel through the filter with no pressure or suction on the gen lines. Overthinking can be as bad as under. Opinions and alternative ideas welcome!

 

[StargazerP303]

1st question is does your engine and your generator share the same fuel tank?
if Yes.. just polish the tank fuel. The more you introduce valves and check valves the more failure points you will have.
IMO Capt. Rob KIS

 

[kloudie1]

Probably going to want to put ball valves in the polishing branch so you can isolate it to change filters. You could put in one check after the ball valve on the intake side of the polishing branch. That should let it work without having to fiddle with the ball valves until you want to isolate to change filter. Only one check needed.

 

[dehler25]

Yes they share the same tank and I have four connections to it, two for engine and two for the gen plus a basically flush level sending unit all within a six by eight inch area, I was using the gen lines as I don't have a direct tank access without cutting into the poly 100 gal tank. The gen lines seemed to be the least invasive and if a problem developed for any reason the auxiliary would be immune. The question was poised for the exact reason that I tend to keep as few fail points in existence as I can and a control valve is manual off or on but require interaction. I overbuild and overthink!

 

[dehler25]

I thought four checks so that when the gen is using fuel it is not able to draw from the polisher line and when the polisher is running it is not pressurizing the gen return as the Racors are suction driven, does that make sense?

 

[StargazerP303]

I think I understand. I'm going to give you a drawing Of what I think your saying. the check valves will cause more problems then you think fuel on the return will have to meet or exceed pressure induced by polisherView attachment 166480

 

[kloudie1]

Like Stargazer, only one check. I would recommend it go between the polishing pump and the filter in the sketch. That would provide the power to overcome the check back pressure without causing pressure backup in the return lines

 

[SEMPERAVANTI41]

You might want to take a look at a
Shelco Single Cartridge Housing Fas394 for the filter. Bought one on e-bay for $40.00 Has much greater surface area to use for fuel polishing.

 

[StargazerP303]

Like Stargazer, only one check. I would recommend it go between the polishing pump and the filter in the sketch. That would provide the power to overcome the check back pressure without causing pressure backup in the return lines

Thanks, kloudie1 Capt Rob

 

[LeslieTroyer]

The line you list as 10psi probably isn’t (there May or May not be 3psi from generator). The tank is open to air so the pressure is line is all from friction of the fuel passing the fuel hose and depends on fuel flow.

If your generator was plumbed correctly it’s pickup is higher than the motors, two keys to polishing are sucking from the bottom and forcefully returning the fuel to the tank for agitation and wall scrubbing.

Unless your fuel is really bad, this won’t do much.

 

[dehler25]

I think the pump pressure is around 7 PSI and the GPH also is not large, I had anticipated a low flow over a long period of time. The gen fuel lines are 1/4 as you said and changing would require replacing tank fittings. The ball valves would not impart a flow restriction at least not a measurable one and the tank vent would be fine as the flow rate is low, although it would seem a net neutral on the vent as drawing fuel out, filtering and returning should not develop a back pressure. I will heed the advice and use ball valves and if I like what is achieved look at increasing the volume/time or if I am not pleased with the performance of the setup I would have a game plan in mind. Thanks for the help!

 

[StargazerP303]

I think the pump pressure is around 7 PSI and the GPH also is not large, I had anticipated a low flow over a long period of time. The gen fuel lines are 1/4 as you said and changing would require replacing tank fittings. The ball valves would not impart a flow restriction at least not a measurable one and the tank vent would be fine as the flow rate is low, although it would seem a net neutral on the vent as drawing fuel out, filtering and returning should not develop a back pressure. I will heed the advice and use ball valves and if I like what is achieved look at increasing the volume/time or if I am not pleased with the performance of the setup I would have a game plan in mind. Thanks for the help!

It sounds like you have it right... My calculations were based on the "unknowns" and assumptions. With the low flow rate and a longer run time polishing, you could omit the one check valve between motor/filter. The main thing is if you hear alot of wuuushie noise coming from the vessel.. Look at your vent..
Best regards, Stargazer II clear and standing by on channel 16..lol

 

[Jake N Eggs]

When a generator and engine use the same tank the generator suction line is usually higher in the tank than the engine suction line. This is so that you can't starve the engine fuel completely with the generator. I would assume that you would want the fuel suction on the polishing circuit to be as close to the bottom of the tank as possible.