Diesel Fuel Expert Advice Needed

[Wallike]

I've got some questions on diesel fuel that I'm being asked and I'm not an expert in that field so I thought I'd ask the folks that are on this site that could offer their educated advice. Thank you in advance!

We have a steam boiler system for heat on our campus. It's a dual system - natural gas - and diesel. Constellation Energy is asking us to go to our alternative fuel source for a couple days. I'm assuming its for load shedding due to the extreme cold temps.

We have a 12,000 gallon diesel tank that hasn't been used since 2014. Do we need to keep this fuel treated? Because it is not. Should we be burning a certain percentage off the tank to keep some fresh fuel mixing in? Because it hasn't. What's the best course of action to make sure this back up fuel system is in the best kept condition for when we may need to rely on it?

 

[Allen]

Yes, diesel that is stored for a long time, such as backup generators, should be treated with a biocide to prevent bacterial growth in the tank. Seems kind of odd when you first think about it, but certain bacteria thrive on diesel fuel and they are known to degrade the quality of the fuel and produce a biological film on the filters which can plug the filters. I would suggest implementing some kind of plan that "tests" your backup plan at least once a year that uses 10-25%(?) of your fuel in storage. First of all, not knowing how long your 12,000 gallon tank will run your operation, but perhaps you only really need to have 1,000 gallons in the tank to last 24-48 hrs, which provides you with ample time to call in for a refill as needed. That way you aren't sitting on a pile of fuel of marginal quality going forward.

What I would do here is change the filters (many long-term storage tanks have filters in line on the exit), burn down your fuel level to something in the range of what you would need for a 48 hour emergency use, and then try to maintain it at that level going forward with regular tests of the system.

 

[Allen]

Also, depending on the setup, a partially filled tank may be subject to condensation over time. So a fuel/water separator isn't a bad idea either. Granted, I am not at all sure how tolerant your setup is for fuel quality, but water is generally considered bad for injectors. All that being said, you will find numerous examples of people firing up diesel engines that have been sitting for 20+ years and they ran "fine" on the fuel that was already in the tank.

 

[SDMF]

Assuming you're not actually running some kind of an engine/motor on this fuel, but, you're using it to make an actual fire under a boiler. A Plumbing/Heating expert is probably more along the lines of what you need regarding fuel quality/stability for this application.

Someone more experienced than I am can better explain the refining and stability differences between Diesel vs. Heating Oil.

 

[eyexer]

If this isn’t running a combustion engine your most likely fine. It’s either going to burn or it’s not. Allen’s point about the bacteria is very valid. But if you have filters for a non combustion engine they probably aren’t fine enough to catch the bacteria. The current Diesel engine filters with extremely small micro counts are the ones affected by this bacteria. I would not recommend the biocide prior to this. The bacteria sticks to the sides of the tank when it’s alive. If you kill it then it suspends and then you have issues. In the spring when your not using it I would kill it then pump it through a filtration system and back into the tank. So find out those couple of things first.

 

[espringers]

it should burn. when i was a wee lad working at the local implement, me and a friend spent the better part of a summer emptying hundreds of full, partially full and nearly empty oil barrels that had been sitting outside for who knows how long into a huge fuel oil tank for heating the shop. you should have seen some of the shit that came out of some of those barrels. but, she burned...

 

[LBrandt]

So does used oil, just need the right stuff to do it. LB

 

[lunkerslayer]

it should burn. when i was a wee lad working at the local implement, me and a friend spent the better part of a summer emptying hundreds of full, partially full and nearly empty oil barrels that had been sitting outside for who knows how long into a huge fuel oil tank for heating the shop. you should have seen some of the shit that came out of some of those barrels. but, she burned...

Yep also since you are using this fuel during the winter months you should have no issues with water since it's now ice on the bottom of the tank which is also where there would be other debris which would be frozen as well. As long as you change the output filter you should be good to go.
I'm assuming this 12000 gallon tank is outside of course since you never stated this.

 

[guywhofishes]

At formerly used defense sites (FUDS) in the Aleutian Islands they often would cut old diesel etc. with kerosene to keep it from gelling and burning cleaner.