Fuel pump for fuel polishing system - Continuous duty pump necessary?

[TCL]

I'm trying to add a fuel polishing system -- essentially an additional Racor primary filter and 12V diesel transfer pump -- that can be run separately from the current filtration system. I've done a fair bit of research online, here and elsewhere, including reading this circa-2013 thread here:

http://www.cruisersforum.com/forums/...her-56586.html

which has a lot of helpful discussion of various users' setups.

One question that remains open for me is whether a "continuous duty"-rated pump is a necessity. Some other sources I read before the above thread suggested yes, but some of the pumps mentioned in the above thread seem to be what the pump makers specify as rated for discontinuous or intermittent duty.

I have a single 95-gallon tank, so a smaller (2.6 gpm) pump (used with, e.g., Racor 120 gph filter) would have to run an hour+ to cycle through the tank twice. Ideally, I'd like to be able to run the polisher for several hours using successively smaller filters.

So trying to figure out whether I need a continuous duty-rated pump. Any help/thoughts would be greatly appreciated, including recs on pump models. Thanks.

(Current: 1979 Morgan 461, 2007 Perkins 4.236, single Racor 500 10micron primary, Napa Gold 3166 secondary, 12V electric priming pump (between primary and on-engine secondary, bypassing OEM lift pump); 95 gal tank shared with generator (Racor 500 10micron and Napa 3386 on generator).
I hope to swap the single Racor 500 engine primary for a dual Racor 500 setup, and use the existing primary filter for the fuel polishing circuit.)

[hellosailor]

I suggest you contact the folks who make the pumps you are looking at, and ask them "Can this pump run at full load for two hours uninterrupted?"

Odds are that you will need one that is rated for uninterrupted service, that the others all have a duty cycle similar to that of consumer paper shredders: Ten minutes on, must rest for 30 after. Whatever their numbers are, the ones built for continuous service will run cooler and last longer than the intermittent rated ones. (And of course, be priced higher.)

[denverd0n]

Personally, I would want a pump rated for continuous duty. Turn it on, let it run, come back later and it's done.


Otherwise you have to be constantly aware of how long it has been running. You have to periodically turn it off, let it cool down, and then start it up again. Seems to me like a huge headache.


Now, admittedly, I have not looked into the price of continuous duty versus intermittent duty fuel pumps. Perhaps the difference in cost is so great that it would make one pause. On the other hand, given the importance of clean fuel to a diesel engine, I don't think this is an area where I would want to go cheap.


Good luck, whatever you end up with.

[model 10]

The magnetic interrupter pumps are cheap and run forever.

[RaymondR]

Simplest solution might be an impeller pump with a nitrile impeller.

[Pete7]

In post 11 of that thread I posted a picture of a diy set up with a facet pump. They are used on vehicles for petrol and diesel pumps. Ours is still going strong. Guess it depends if 90 lph is a big enough flow rate for you.

Pete

[noelex 77]

On our old boat we had a small Facet pump similar to the one Pete shows in the photo. It was not new when installed and ran for 5 years or so on average 2 hours a day 300 days a year. It was replaced with a similar pump that was still going fine when we sold the boat a few years later.

Our new boat has a larger Walbro pump rated for continuous use and greater than 18,000 hour life, but given the lifespan we had out of the much cheaper pumps it is overkill.

[skipgundlach]

Hi! Did you know about the Morgan 46 group on FB? https://www.facebook.com/groups/2125677644383657

But, to your question, and some other stuff not directly related, in favor of fuel polishers OTHER THAN RACOR:

We had installed a fuel polisher in our initial refit (immediately before
our wreck); the tank was about half empty and had experienced in the range
(based on the storm duration and the period of waves) 3-5000 impacts. Ran
the polisher in the first yard, changed the filter, ran it again on the
rock-and-roll trip back to the original yard, changed the filter, and have
yet, 3000 hours later, to change a Racor.

If you'd like to see our fuel polisher, all parts from McMaster-Carr, click
here (with apologies for lots of other pix intermixed:
Pictures: Flying Pig Early Refit + Projects/Flying_Pig_Has_Flown-Splash_and_More_Work/Getting_Close-Nov06

Morgan 461 #2
SV Flying Pig KI4MPC
See our galleries at Web-Folio -- Your Portfolio on the Web !
Follow us at http://groups.yahoo.com/group/TheFlyingPigLog
and/or http://groups.google.com/group/flyingpiglog

I expect to pass this way but once; any good therefore that I can do, or any
kindness that I can show to any fellow creature, let me do it now.
Let me not defer or neglect it, for I shall not pass this way again.

- Etienne Griellet

[mvmojo]

Yes, you want a pump rated for continuous duty! Unless thermally protected, intermittent duty pumps tend to overheat and burn up the motor if run beyond their duty cycle. Is heat really what you want when handling fuel?? Additionally, I think you should plan to filter your fuel for longer than what the pumps rating equates to two passes of your tank capacity. Rarely do pumps actually meet their full capacity when pushing or pulling fuel through a filter. Plan to run the pump for several several hours. We have 4 tanks on our boat. At least once a year, we continuously polish the fuel in each tank for 24 hours non-stop. As a result, our fuel is always clean, bright red in color and water free. Since we installed the fuel polishing system over 10 years ago, through thousands of hours of operation we've not had a single problem with fuel contamination. We use a Gulf Coast filter system and a Walbro pump. Our system is also plumbed such that any time we're using fuel, it is going through the Gulf Coast filter. This gives continuous polishing even when underway. We have a Racor filter plumbed to act as backup in the event the main filter gets clogged. This is accessed simply by turning a valve. To our mind, with a single engine trawler, good fuel polishing and redundancy when underway are essential.

[skipgundlach]

PS the filters themselves are SS core wound, 30 and 10 mu each in series. We run the polisher any time the engine is running (power available) and any time under way when we're good on battery state.

Rocky seas the best, like above, due to mixing and scrubbing of your fuel tank walls. With a 461, you have one, next to the mast and galley drawers (which I presume you know), so it's a single feed...

[skipgundlach]

My particular pump has been discontinued, but any similar pump (I believe the type to be called a 'pulse pump') would work.

Ours chatters while it develops suction and then settles down (in a few seconds) to being very quiet...

[Cheechako]

The Facet and Walbro brand pumps are good quality. BTW you can get huge diesel filters , probably 3-4 times the capacity of a 500 Racor, for dirt cheap. The mounting head is like $20 and the filters less than Racor. No need to use Racor for that task.

[skipgundlach]

Our pump looks like this:
https://second-wind.net/products/wal...-33-gal-hr-1-4
but it's 12V.

That line has been discontinued, but read the description; the current line of tha type of pump would do you just fine...

[SV Bacchus]

What would happen to your non-continuous duty pump when you turn it on and, egads, forget about it for 2 or 3 hours?

I think the price difference between the two pumps styles isn't that great once you amortize it over 5 or 6 years. Go continuous, it is the decision that makes good sense.

[hellosailor]

"What would happen to your non-continuous duty pump when you turn it on and, egads, forget about it for 2 or 3 hours?"
It if was expensively engineered, like home paper shredders, it would overheat from running too long, and then throw a thermal safety breaker and shut down, with no harm done. Turning itself back on after it had cooled.
If it was "just" a pump, and didn't have an overheat safety breaker built in? It would overheat and either freeze up and/or catch fire. Sometimes considered an undesirable behavior for anything involved with fuel handling.

Engine starter motors are the most common "intermittent use" motors we all use without noticing. They are built for high impulse power, and if you run them for 20 seconds, they may require 20 minutes of cool-down, or else the heat-swollen coils grind against each other, resulting in the eventual failure of the starter. There's no "safety" involved there, and that's normal.