Fuel Oil Tanks and Proper Piping

JoeC

I was taught many years ago here in Alaska, that anytime that an above ground fuel oil storage tank was to be utilized, that it was proper to run a 'one-line' system (no return piping) because the warmed fuel returning to the tank will induce 'condensation' build up in the tank. I'm looking for a more scientific explanation of this phenomenon which, after dipping thousands of tanks, I've found to be true, but myself can't explain the reason for. Thanks for your inputs! It's already snow season here if anybody wondering.

Alan R. Mercurio

Joe, I can't put it in scientific terms for you but I'd like to share my view on this issue. I'm sure you know heat tends to be attracted to cold surfaces. It's like when you go out to your car in the morning and there is condensation on it or like the dew on the grass. when any surface is cool and the area around it begins to become warmer it just naturally creates condensation.

So picture the fuel line from an outside tank. the fuel running through it is close to the out door temperature which for you this time of year is very cool then it travels inside to a warmer environment once it is introduced to the fuel pump it becomes even warmer. Now you can see how condensation is already starting to build in the supply line.

Once the fuel exits the fuel pump it's slightly warmer than the room temperature imagine the effect that will have once that fuel reaches the outside of the buildings environment!

Now you have even more condensation building up which is ultimately introduced to the oil supply tank.

It's easy to see how all this can be avoided by simply running a single line system. And in areas such as your in if a two line system is needed it may be prudent to consider using a tiger loop?

Well, I hope I have made some sense here.

Your Friend in The industry,
Alan R. Mercurio
www.oiltechtalk.com

JoeC

Thanks for the input. I was looking more for 'where exactly does the condensate get introduced, if its simply by warming it, where did the water enter the system? Was it naturally dissolved in the oil and solidified once warmed? Or, if you returned to the tank, and the return line was submerged, lets say four feet below the oil level of the tank, what effect would several gallons of 50 degree oil returning to said tank, have on the remaining thousand gallons or so present in the tank? I've seen quite a few frosted tank fill and vent pipes in my time, and have a few ideas of my own on where the moisture comes from. I'm picking brains, thanks again!

Steve Levine

How about from

the air above the oil in the tank. As you know, the tank is vented.