Thursday, April 6, 2017

Got Gas?

About a year and a half ago, I wrote a short post about lockpicking. In the first paragraph I stated “I don't condone and can't recommend breaking laws for petty reasons, but at the same time I believe that tools and skills are neither good nor evil by themselves, and that applies to today's article as well.

Gasoline and diesel are common fuels that we pump into our vehicles on a regular basis, and some of us store back-up fuel. We've already covered fuel storage, but what if you're away from your stored fuel when TSHTF? Where are you going to find enough fuel to get you home if the pumps aren't working due to a sustained power outage?

Gas stations don't normally have back-up generators, but they do have underground storage tanks full of fuel.

Anatomy of a UST

This is a generic model of an underground storage tank (UST). The American EPA made drastic changes to the laws covering USTs back in 1988, requiring that existing tanks meet new standards or be replaced with new tanks that met the standards. Most of the tanks you'll find in the US will be laid out similar to the picture, so I'll use it to point out how to access the fuel in the tank if the pumps are dead.

From left to right in the picture, the tank has several connections:
  • Vent pipe
  • Fill pipe
  • Fuel pump
  • Meter (AKA gas pump or island)
Without electricity to power the pump, it and the meter are dead and not much use. If you have a generator handy, you may be able to get them to run, but any island that takes a credit card will also need a phone line or internet connection before they will dispense fuel. Good luck with that in a grid-down situation! Additionally, the circuitry inside the meter/island will have anti-tamper hardware or firmware to prevent bypassing the electronics.

The vent pipe ties into the top of the UST and allows vapor flow to and from the tank as it is filled and emptied. The vent pipe will normally be run to a building or other structure near the tanks, and extends at least 10 feet in the air so that any vapors pushed out of the tank while filling it are routed away from any possible ignition source. Vent pipes are usually capped with a mesh screen to keep debris and insects out, and can be as long as needed. 

Last, and most important, is the fill pipe. You've probably driven over the fill pipe connections dozens of time without even noticing them -- they're the bumps in the driveway near the islands. Here's a picture of a common fill point.

Photo credit: Chaplain Tim

They are about 10 inches in diameter and normally raised an inch or two above the surface to keep rain water out. The lid will be heavy so it will stay in place with cars driving over it.

Photo credit: Chaplain Tim
Once you take the lid off, here's what the inside of the hole looks like.

A simple lock is all that secures the cap, but remember that you're working on a fuel tank, so don't use anything that will create a spark to remove the lock! 

Bolt cutters should fit into the hole and still open enough to get around the shackle of the lock; picks could be a challenge due to working in a hole and at a weird angle; and I doubt you could get a pry bar into position within the limits of the hole. 

Grinders and cut-off wheels are a bad choice.

After the lock is off, simply lifting up on the ring, or ears of the latch, unlatches the cap and it lifts off with ease. The ring is supplied to make it easier to remove the cap while wearing heavy rubber gloves, a safety measure for the guys who handle fuel for a living.

Once you have the cap off, you'll have a three-inch or better pipe running straight down to the fuel. Getting the fuel out will require a pump and some hose or pipe.

Diesel is a lot safer to work with (it has a higher flash point than gasoline), so pumps rated for diesel are easier to make and thus cheaper. Finding a pump rated to transfer gasoline is neither simple nor cheap, and finding one that can lift liquids more than a few feet makes the search even harder.

Since you're trying to lift a liquid up out of a tank, a siphon isn't going to work. Centrifugal pumps require a full pump before they will work, so unless you have a way to “prime” your pump they are a poor choice; what you are going to need is a “positive displacement” pump of some sort. For shallow tanks that are mostly full, any of the pumps rated for gasoline with a suction “head” rating of at least 8 feet will work.

Getting the last few feet out of a UST will take a submersible pump dropped into the tank, and that is a DIY project that I could piece together from a spare automotive fuel pump and some extra wire. The fuel pump in your car is likely inside the gas tank, so they're designed to be submerged, the hard part would be sealing the wiring up to avoid any possibility of sparks.

This is a subject that requires more research, I will be coming back to it and posting an update.

The small station I help take care of has three 5,000 gallon tanks underground that get topped off about once a week. Larger stations that do a lot more business will have more and larger tanks, and get resupplied more often.

We have to measure the tank levels on occasion, and use a 14 foot long “stick” with graduations every quarter-inch dropped down the fill pipe to do so. This means that the bottom of our tanks is not more than 14 feet below ground (actually closer to 10 feet), so 15 or 20 feet of hose or pipe would be plenty to get to the fuel. 

Just about any metal pipe would work as long as you make sure it is grounded to the tank before moving fuel through it -- flowing petroleum products create static electricity and can cause a spark. Keep the pipe in contact with the fill pipe, or actually clamp a grounding wire between the two. 

Plastic tubing is easier to work with, being more flexible than metal pipe, but is harder to ground to the tank. Pump slowly and minimize the creation of vapors to reduce your risks. Check the type of plastic you are using to make sure it is safe to use with your fuel. Gasoline will dissolve some common plastics and diesel can make them swell up.

I don't want anyone to see this post as an invitation to steal fuel or a “how-to” rip off a gas station, but I can imagine situations where knowing how to access the contents of a UST would be ethical, legal, and useful. If there is any doubt, the standard disclaimer applies:
This information is provided for informational and educational purposes only. The author assumes no liability in how you use this information and cannot be held responsible for your actions.

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