Fuel/Air Separator

Guess this is technical. For any boat with a built in tank and vent tube.
Surging gas or diesel while filling can explode back out the fill and/or up the vent causing embarassment and a fine. Here are some tests done by

http://www.boatus.com/foundation/fin.../solutions.htm

that seem objective. I was convinced the
Racor Lifeguard Marine Fuel/Air Separator LG100,
which got the best marks for keeping all the fuel in the tank whatever size it is and is installed in the vent line is the way to go. Found lowest price at go2marine for $54.32. That's still pricey, but it's 4" D and almost 10" long!! The much smaller gas only unit goes for $30 more. The diesel/gas LG100 got the no fail no spill prize in above test. Check it out.

Where to rig it is the problem. :confused:

While checking this link I saw the list of precautions;

http://www.boatus.com/foundation/fin.../Solution3.gif

Why do you suppose they don't want you to use a detergent to disperse the spill? It would seem to be more environmentally sound. Surely the concern is not the tiny bit of detergent involved? Maybe it is a flashback to the early 70’s when industry dumped so much of the stuff in rivers that they foamed? Then again, maybe it just makes it easier to prosecute a spill?

Makes me glad I am not a powerboater, and fueling is not a big part of my every day experience.

Your posting this was timely, as soon as I can figure out how to get it below, I guess that the triton tank I purchased will need some sort of baffle in line with the vent. :confused:

(I was going to plumb it with a simple loop above the standard vent fitting on the transom)

Lo Craig, There sure is a whole parade of bottles of cleaning and scrubbing and polishing stuff one can buy to lubricate the boat. Most of it can't be all that good for the water. I've used some low sudsing biodegradable liquids, thinking I might be forgiven - but it sure feels funny watching the trail of bubbles. Not so funny when some stranger is watching the same plume. I'm sure any detergent is as bad as the oil is for the birds and fish. Having that absorbant ring around the fill at least psychologically would be good.

You put it in the garbage on shore where it's taken to the dump. Then it enters the same water by a more devious but legal method.

The LG100 is successful they say because the design interrupts the shot of fuel entering the vent and acts as an accumulator or reservoir as the air separates and vacates. The fuel that wants to get out has an alternative place to go in the chamber as it falls back into the tank. It also happens quick enough so that the automatic shutoff on the nozzle activates befor you can overfill the tank, no matter what size it is - like a small sailboat fuel tank - or how fast its coming out of the pump. That's what I understand. Of course you are trying to be more guarded in your filling (especially when you "hear the tune changing") - and you are trying to remember how much you have to fill - and the kick-off at the nozzle BETTER work - etc. If this device is for real, then it seems well worth the price for a whole lot less twitching.

The Racor device compared to the double fuel fill invention that requires an overflow tube between the two seems preferable - altho it will take up more space. Seems more suited to us sailboaters too???

Thinking that mounting the LG100 at the vent as it exits the tank, continuing the vent up and out, is the best way. Get separation immediately at the tank. Any ideas on this? And where do you terminate the vent? Lead it up a stanchion??? Where the vent ends has always been a problem, because IF fuel gets out THERE you don't want it to create problems or fire hazard - nor do you want water to enter either??? :confused:

Makes one wonder why an expansion chamber/vent has never been designed into builtin tanks as a matter of course. It would be a small box or sphere on top of the main tank where the separation of air and fuel would occur just like the Racor LG100.