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How to store DEF 

If you use diesel engine driven equipment – especially EU Stage V compliant engines – you’re likely already using DEF (diesel exhaust fluid/AdBlue). DEF is essential for keeping diesel equipment running smoothly while reducing emissions released into the atmosphere. 

DEF is widely used throughout the construction industry, but many issues and questions remain about storing DEF onsite.  DEF differs from fuel, yet proper handling is vital to maintain purity. Many users are yet to understand how DEF works and its importance. We’ll take a look at the fluid in our guide, why it’s a legal requirement and storage regulations that need to be followed. 


What is DEF?

DEF is the acronym for diesel exhaust fluid, a non-toxic mix of deionised water and urea. Known as Adblue in the UK, it was introduced by the Environmental Protection Agency (EPA) in 2010 as part of the Clean Air Act. As per these standards, heavy-duty vehicles and machinery, such as vehicles with stage V engines,  off-road construction equipment, often use DEF. 

The purpose of DEF is to reduce emissions released from diesel engines, as part of a Selective Catalytic Reduction (SCR) system. Without it, many engines release harmful emissions into the atmosphere and can cause engine shutdown. 

What is the EU Stage V legislation?

EU Stage V legislation is the latest emissions standard for Non-road Mobile Machinery (NRMM) with spark/compression ignition engines. NRMM includes equipment such as generators, lighting towers, pumps, etc

For Engines with an output of 19 kW and more, the permitted values for NOx and PM (Particulate Matter) emissions are one level stricter than previous standards. In addition, new PN (Particle Number) standards have also been set, making the new emissions standards generally the strictest in the world.

How does DEF work?

DEF is added to your equipment’s exhaust stream, creating a chemical reaction that turns nitrous oxide (NOx) into nitrogen and water. This non-toxic substance minimises the amount of carbon released without compromising on the engine’s power.

The key with using DEF is that it cannot run dry. If a vehicle or piece of equipment runs low, performance is lowered and may eventually stop working. This is where storing DEF in bulk helps save money and prevent delays onsite – no more waiting for deliveries when there’s no diesel exhaust fluid available. 

However, DEF does have an expiration date, and if it’s contaminated, its performance is affected. Your DEF storage solution must keep your stock secure and clearly labelled to help avoid cross-contamination.

Refuelling equipment with DEF

How to store DEF

DEF isn’t a fuel – it’s a liquid used to reduce and treat exhaust emissions, meaning you cannot treat it like diesel. Maintaining its purity should be a priority. 

Due to its non-toxic nature, DEF  is not as regulated as fuel, but there are still some standards to follow.  ISO22241 is the standard for transporting, handling and manufacturing DEF, and it details the requirements for safe storage. 

When storing DEF, you should:

  • Separate your stock from other fuels and chemicals to minimise contamination. Instead, store DEF in an isolated area with minimum surface water drains. 
  • Also, ensure it is out of direct sunlight to avoid losing its urea potency. 
  • Regularly clean dispensing nozzles, as well as equipment and machinery. 
  • Make sure only to use dedicated DEF systems – do not mix with other fuels. 
  • Store your DEF in a steel or plastic tank with secondary containment. This is a recommendation of the Environment Agency (EA). DEF is corrosive to some metals, so steel and plastic is best suited. 
  • Because of this, avoid overfilling your DEF fluid in case it spills over and makes contact with other metals. 

Western Global has designed a unique DEF storage solution that differs from the market. Our DEFCube is a bunded, plastic inner tank designed for long-term bulk storage of DEF. Its secondary containment is a steel outer that helps with temperature control, meaning your DEF will retain its usability even in the coldest climates. Find out more about the DEFCube. 

What is the shelf life of DEF?

The shelf life of DEF can depend on its storage conditions, but generally, it lasts one to two years. Once expired, it’s less effective and can lead to issues with equipment and machinery. 

You should find the expiration date of your DEF clearly marked on its container. However, if you’re unsure, you can easily tell the condition of your diesel exhaust fluid by simply looking at it. DEF is naturally clear – if your stock is cloudy or has particles, it’s likely expired or contaminated. 

What temperature does DEF freeze?

DEF freezes at -11°C and can expand up to 7% when frozen, potentially damaging your tank – especially when full. Some try to add additives to the DEF to prevent it from freezing, but this can affect its purity and effectiveness. If you leave your diesel exhaust fluid to thaw naturally, it should still be usable. 

Maintaining the temperature of your DEF has never been easier with our DEFCube. Our tank is bunded with a poly inner and steel outer, providing complete weather-proof containment that aids temperature control. Pipes and fittings are also stored behind a lockable cabinet to protect them from the elements. With these measures in place, you can store DEF in bulk for long time periods, no matter the climate. 

Problems with storing DEF

Storing DEF correctly prolongs its shelf life, minimises contamination and ensures that equipment and off-road vehicles can perform at their best. But as DEF must be treated differently to other fuels, users find a handful of issues. 

We’ve answered several of your questions regarding DEF storage below, but if you want to know more about diesel exhaust fluid and are looking for the best containers, then get in touch with our team. 

What happens if you put DEF in your Diesel Tank? 

If DEF is mixed with diesel, it can seriously impact your engine. It can clog up pipes and affect the lubricating properties of the fuel, leading to more wear and tear for your engine. In the worst cases, the engine will just shut down. 

When this happens, fuel systems need to be flushed and thoroughly cleaned to remove all traces of contaminated substances. You can’t reuse contaminated DEF, so ensure this is disposed of safely. 

This is why DEF is often stored in blue containers, and its filling caps are blue – to help differentiate it from other liquids. Only dedicated pumps and containers should be used for DEF, with all fittings safely closed and locked away to prevent drips or leaks. 

How can you prevent diesel exhaust fluid spills? 

Like any liquid, DEF fluid spills can happen. But the difference is that spilt DEF isn’t a major issue. 

We mentioned earlier that there are less regulations to follow when storing DEF, so you’re less likely to be fined. The only time a DEF spill is cause for concern is if it mixes with another fuel or it’s leaked down a drain. DEF can corrode some materials and may affect the drainage pipes if this does happen. 

In the event of a DEF spill, make sure the solution does not enter any drains or waterways. Then, contain the spill with a spill kit and dispose of it safely.

Diesel exhaust fluid spills should still be avoided. The DEFCube’s bunded design offers complete containment, meaning that any DEF leaks would spill into the outer tank. The tank  is robust and can withstand wear and tear, providing next-level protection for your diesel exhaust fluid. Leakage risk is also minimised with pipes secured behind the cabinet – you can still refuel equipment with the hose while it is locked. 

What happens if you run out of DEF?

If DEF runs dry, engines won’t start and sites can be shut down for weeks or even months in worst cases, as you wait for the next delivery. If there is fuel contamination, you must also wait for equipment to be replaced. You should manage your DEF consumption as you do fuel, ensuring there’s always more fluid ready to use. 

Bulk DEF tanks are ideal for storing DEF onsite, no matter the circumstances. We’ve made sure that our tanks are fit for purpose, with the DEFCube, a robust and ready solution that helps retain the purity of your DEF, maintaining its shelf life and saving you time and money. 

The tank  is designed for mobile refuelling, meaning it can be easily forklifted to and from site, and even stacked when empty to save space. There’s also minimal set-up time, so once it’s dropped onsite, you’ll be up and running in no time.

DEF storage from Western Global

We designed our DEFCube with our customers in mind. We listened to what our customers wanted and manufactured a next-level DEF storage solution unlike those currently on the market. 

Providing 110% bunded containment for security and protection, our DEFCube is ideal for  hot and cold climates and can be lifted into challenging environments. Refuel generators and equipment as and when needed, knowing that your diesel exhaust fluid is safely contained. Find out more about the DEFCube or request a quote from our team.


Western Global's DEFCube

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