Since the onset of recent events, the aviation industry has been one of the most critically hit industries globally. Not only were people’s jobs affected, but it also caused significant changes to how airlines and airports run. Fewer flights meant fewer fuel consumptions, leaving some aviation fuel stagnant for months.
This also applies to all kinds of aviation fuel, including jet fuel, one of the most important transportation fuels in the industry. So, what happens to the jet fuel left stagnant in aircraft or storage tanks for extended periods? How long does jet fuel last?
All About Jet Fuels
Before we dive into the guidelines for storing jet fuels, let’s discuss what this type of aviation fuel is first:
Jet fuels are kerosene products. It is a middle-distillate product commonly used for commercial and military jets. While they are mostly used as transportation fuel, kerosene is also widely used worldwide for cooking and heating.
In the United States, jet fuels are mainly used by North Atlantic Treaty Organization (NATO) nations for military establishments. (Read Safest Places In South America Guide)
Shelf Life of Jet Fuel
Fuels in general need to be safe and reliable. Using already bad fuel puts the aircraft and its passengers at risk, and it’s something no one ever wants to happen.
The good thing about jet fuel is that it can last for years as long as it is in the right conditions. As for its shelf life, kerosene typically lasts between two to five years.
The key to avoiding jet fuel going bad is to avoid the factors that can affect the long-term storage of kerosene. Here are some of what you should look out for:
Water
Water is one of the biggest enemies of fuels when stored. The presence of water tends to degenerate the fuel, so it’s important to always be on the lookout if there’s a source or body of water that can enter your storage tank.
Microbial contamination
When water is present in the storage tank, it makes the fuel prone for microbes to grow. Microorganisms can damage not just the fuel but also the fuel system. Some of its damaging effects include degradation in quality, emulsification, sludge formation, and system corrosion.
Oxidation
Due to oxidation from the air, jet fuels are at risk for gum formation. When fuel is exposed to atmospheric oxygen, the catalyzing compounds and the environmental condition of your storage area contribute to uncontrollable oxidation. This leads to the formation of not only gums, but also resins, particulate, and acid formation in the jet fuel.
Temperature
If you fail to keep the storage area at the right temperature, this poses risk to your fuel. If the temperature is too high, the water solubility of the fuel also increases. This means condensation is more absorbed into the fuel. The same goes if the temperature is too low – suspended water coalesces and settles.
Copper
Jet fuels do not like catalytic metals like copper. The presence of copper can cause the fuel to become unstable when flowing in an aircraft fuel system. Copper causes carbon deposits to form, which can potentially harm the fuel exchanger’s performance.
Additives
Some additives can reduce the surface tension of jet fuels that act as surface-active agents. Once it becomes lower, fuel becomes more water-soluble, making it hard to drain.
Now that you know what should be avoided, here are the steps you should do to make sure that your jet fuel is safe for long-term storage:
Good Housekeeping
Maintaining good housekeeping is key to keeping your jet fuel in tip-top condition. It should only be put in stainless steel or aluminum tanks and equipped with a sump drain. Sump drains help remove accumulated water in the tanks to keep them as dry as possible.
The tanks should also be properly ventilated and provided with manual water drain valves for storage tanks that are above the ground. (Learn How Much Does It Cost To Go To Thailand)
Testing for microbial contamination
Ideally, jet fuels should be tested monthly to see if they have microbial growth. If not possible, just test the fuel from time to time to see if there are changes in the quality or color of the stored fuel. Once it shows signs of microbial contamination, take the necessary steps before it’s too late.
Regular inspection of environmental condition
Apart from regularly checking the fuel itself, the environmental condition of the storage tank should also be checked. Access points, seals, and caps of the tank should also be inspected when checking the fuel and ensure that it’s tightly closed at all times.
You should also ensure that the storage tanks have access manways, venting and overfill protection, and identification signs on tanks and piping.
Added inspections after intrusion concerns
Inspections are further needed after a rain or snowstorm since they put the storage tanks at higher risk. Driving winds also contribute to possible water and microbial contamination of fuel, so it’s best to prevent it before it spreads.
Good additives
While there are bad additives, there are also good ones, such as antioxidants, antistatic agents, power boosters, and antifreeze additives. One of the most known antifreeze additives includes fuel system icing inhibitors (FSII). An approved FSII must have a compound called DiEGME or diethylene glycol monomethyl ether. Adding this can help protect the small amount of suspended water from freezing.
When it comes to this additive, one of the most popular brands is Prist which we will discuss further below.
What Is Prist?
Manufactured by Prist Aerospace Products, Prist is known to make anti-icing additives and window cleaners. They manufacture products that are made to meet military specifications.
For its anti-icing additives, Prist’s mainly uses the ingredient DiEGME. Once mixed with jet fuel, it migrates to small amounts of water and lowers the water’s freezing to -46 degrees F, the recommended temperature for the suspended water.
If you plan to add it to your jet fuel, it should be added while fueling and not after the process. Typically, Prist is heavier than the fuel and will just sink to the bottom if not added during the fueling process.
Key Features of Prist
- Completely soluble in water
- Dynamic viscosity of 3.9 megapascals at 20 degrees C
- Kinematic viscosity of 3.82 to 3.89 square millimeters per second at 20 degrees C
- Vapor density of 4.2 at 20 to 25 degrees C
- Relative density of 1.02 to 1.025 at 20 degrees C
- Flammability limit of 1.2% LEL and 22.7% UEL in air
- Specific gravity of 1.023 at 20 degrees C
Benefits of Prist
Apart from it being a generally good add-on, it also offers a whole round of benefits:
No need for fuel heaters
Some production jets have fuel heaters that warm the jet fuel before it reaches the injector to thaw the ice crystals that might have formed. Since Prist is anti-icing, you don’t need fuel heaters to keep your jet fuels at the right temperature. Just add it to your aviation fuel and you’re good to go!
Prist has biocidal and pesticide properties
Since bacteria tend to grow in dark and wet areas, Prist’s biocidal and pesticide properties help kill bacterial growth in your storage tanks. Hence, keeping it clean and safe.
Frequently Asked Questions
If you have further questions about aviation or kerosene shelf life, this might help:
How long can kerosene be stored?
Kerosene can be stored for up to five years.
How long does kerosene stay good?
When kept properly, kerosene’s shelf life lasts about two to five years.
Why does kerosene go bad?
Kerosene usually goes bad because of condensation. When water is added to the kerosene, it dilutes the fuel.
At times, kerosene also develops bacteria that is harmful to the fuel.
Can you still use bad kerosene?
Yes, you can still use bad kerosene, which is still considered safe, but it might not be as efficient as before. (Read How Many Days Prague Guide)
Final Thoughts
Regarding storing aviation fuel, safety is always the top priority in the industry. The good thing about jet fuels is that they can be kept longer. That’s why it’s essential to know everything about their shelf life, the proper guidelines for storing them, and the potential risks of keeping them for a long time.
The bottom line is with proper fuel management; it’s possible to keep your aviation fuel for long-term storage without compromising its quality. There is no need to worry about possible hazards and concerns as long as you keep the guidelines and reminders in mind.
