What You Need To Know About Diesel Exhaust Fluid (DEF)

What You Need To Know About Diesel Exhaust Fluid (DEF)

Diesel Exhaust Fluid, otherwise known as DEF, is a required component of any diesel-run vehicle. Whether you’re new to working with this fluid, or you simply need a refresher course, we’re here to help. Here are some frequently-asked-questions and quick DEF facts to make your job easier.

What is Diesel Exhaust Fluid and Why Is It Required?

DEF is a fluid that is non-hazardous, non-flammable, and non-toxic. This exhaust fluid is made up of 67.5% deionized water and 32.5% urea. It has one simple (but very important) job to do – reduce the harmful emissions otherwise ejected by diesel-fueled vehicles. 

About ten years ago, the EPA (Environmental Protection Agency) made this exhaust fluid mandatory for all diesel vehicles in the United States. It was time for a solution to clean up the air and reduce harmful pollution.  

How Does DEF Work In My Diesel-Run Vehicle?

DEF is pumped into the vehicle’s DEF tank. When the engine is running, the exhaust fluid enters the SCR (Selective Catalytic Reduction Systems). The SCR then sprays the DEF directly into the diesel exhaust stream. Once the DEF has made contact with the exhaust, ammonia from the DEF effectively breaks down the harmful emissions of nox (nitrogen oxides) into simple, harmless nitrogen and water. 

Does DEF Go Directly Into the Diesel Fuel?

Nope! Never! 

The DEF never makes direct contact with the diesel fuel itself – it is only sprayed into the exhaust stream. In fact, if DEF were allowed to enter the diesel fuel tank, it would contaminate the engine fuel. If the engine was then turned on, you would likely do significant damage to your vehicle. In addition to unwanted gummy deposits that would build up over time, the exhaust fluid would corrode metals and damage the fuel system. So basically, don’t mix up your fuel and DEF tank unless you want to deal with a world of headaches. 

What is an SCR?

As mentioned above, SCR is short for Selective Catalytic Reduction systems. This is the emissions control system within the vehicle that allows the DEF to make direct contact with the diesel exhaust. The SCR pushes the liquid DEF through a catalyst into the exhaust stream, which sets off a chemical reaction to convert the nox into nitrogen, water, and small amounts of carbon dioxide. These safe emissions then exit through the vehicle’s tailpipe. 

The SCR is responsible for greatly reducing the pollution otherwise emitted from diesel-run vehicles, protecting the environment and enhancing overall air quality.

Can My Vehicle Run Without DEF? DEF warning light

When it comes to protecting the environment, there’s no messing around. You will see a warning light on your dashboard alerting you to the fact that you’re running low on your exhaust fluid. Don’t ignore it.

If your DEF tanks becomes empty, a few things will happen. First, you’re going to lose a lot of engine power. Consider this your warning to get to the nearest fueling station and refill. If you ignore the warning, the vehicle will eventually throw a fit and stop working altogether. That’s right – it will refuse to budge until refilled. If you don’t want to deal with costly time delays for your business due to a vehicle that won’t work, it’s best to take the DEF warning seriously.

Save yourself the trouble of becoming stranded without a refill option nearby. Either have some DEF stored or know exactly how much is in your tank and plan accordingly. 

Does DEF Negatively Affect My Fuel Economy?

No, DEF should not reduce your vehicle’s fuel economy. In fact, many who work directly with diesel vehicles have claimed their fuel economy has improved since DEF became required. The engine’s performance is likely to improve as well. And as mentioned, diesel engines that do not have DEF are going to perform sluggishly or stop performing completely.

Where Can I Find DEF?

When it comes to purchasing DEF, you have a couple of options.

  1. Local Automotive Parts Store: If you need just a few gallons in your vehicle’s DEF tank, you can easily find a small container of it at a local automotive parts store. You can also find it at a larger chain store like Walmart.
  2. Fueling Stations: If you are out on the road quite a bit, it’s likely you’ll need to fill up at local fueling stations. Many times, you can find DEF offered at diesel gas stations. You may also find them at some regular gas stations as well. The best idea is to have your phone handy and do a little research before your trip, mapping out exactly where you will fill up on DEF along your way.
  3. DEF Manufacturers: If you manage a large fleet, you may be more interested in storing bulk tanks of DEF instead of constantly filling up at fueling stations. This gives you the ability to organize the DEF tank fill-ups of each vehicle and save on costs as well. 

How Can I Store DEF Safely and Correctly? 

Here are some quick, easy tips for correctly storing your bulk supply of DEF.

  • Store in a cool, well-ventilated area.
  • Avoid storing your containers in direct sunlight. The more sunlight, the more the DEF will degrade over time.
  • Use bulk containers that are specifically designated for DEF storage only. Choosing to use a container that has previously held another oil or substance is likely to contaminate the DEF, which can greatly damage the SCR system in your vehicle.
  • Store the DEF at temperatures between 12° and 65° Fahrenheit. Keeping it from rising above 65 degrees is going to greatly lengthen the shelf life of your DEF from one year to two years or more.

What if My DEF Gets Too Cold or Too Hot?

DEF can freeze when ambient temperatures drop below 12° Fahrenheit. Frozen DEF should not degrade the product and will be reusable when it thaws. However, frozen DEF still presents a problem as it’s unusable throughout the winter, leaving you without your vehicles when you need them.

When it comes to shortening shelf life, hot temperatures are the main culprit. When the DEF is allowed to reach above 86°F for a sustained amount of time, the DEF will become compromised and degrade. When this happens, it will shorten the shelf life by a year or more. 

So what should you do to properly regulate your DEF’s shelf life?

The smart option is to carefully regulate the temperature of your DEF while it is in your bulk storage. 

Luckily, there is a low-maintenance, set-it-and-forget-it solution that will ensure your DEF is good for the optimal amount of time – Powerblanket DEF Tank Heaters to the rescue!

During the extreme seasons, ambient temperatures do not cooperate with your storage temperature needs. For this reason, we recommend checking out our DEF tank/tote heater, which is one of our best agriculture heating solutions on the market.

Get a Powerblanket DEF Tank Heater

Get the heating solution that will effectively moderate your DEF’s temperature. At Powerblanket, our DEF tank/tote heaters are the optimal solution to perfect, effortless temperature control. Here’s what you can expect from one of our top-of-the-line DEF heaters:

  • Prevents Overheating and Freezing
  • Maintains Optimal DEF Temperature
  • Provides Even Heat Distribution
  • Easy to Install and Maintain
  • Safety Certified to UL and CSA Standards

If it’s time to protect and preserve your DEF supply, contact Powerblanket’s temperature control experts today. Reach us at 866.945.4203 or by email at [email protected]

Learn More About DEF Totes

The Powerblanket DEF tank heater is the most efficient and effective way to heat and store diesel exhaust fluid.

DEF Freezing and DEF in Cold Weather

The Polar Vortex is sliding down over the country.  Have you taken precautions to prevent DEF freezing in the increasingly cold temperatures swiftly approaching?  We have tips and guidelines to help you with DEF in cold weather.

Understanding DEF and SCR

Diesel Exhaust Fluid (DEF) is a non-hazardous solution, which is 32.5% urea and 67.5% deionized water. DEF is sprayed into the exhaust stream of diesel vehicles to break down dangerous NOx emissions into harmless nitrogen and water. NOx is an element in exhaust that has been blamed for acid rain, smog and raising the overall greenhouse gas levels of the planet.  DEF is not a fuel additive and never comes into contact with diesel. It is stored in a separate tank, typically with a blue filler cap. This system is called Selective Catalytic Reduction (SCR).  SCR and DEF have been used for decades in other commercial and agricultural applications.

Storing DEF

DEF should be stored in a cool, dry, well-ventilated area. The ideal storage temperature for DEF is between 15ºF and 65ºF (-9ºC and 18ºC). It should not be exposed to direct sunlight for long periods of time as the urea will decompose. When possible, DEF packages and bulk storage should be kept indoors in temperature-controlled environments.  Use the right container. DEF is mildly corrosive, and should be stored in containers of HDPE plastic or stainless steel. 

DEF Freezing Protection guide graphic

DEF Expires

Check the expiration. The storage life of DEF varies. The urea is vulnerable to degradation from sunlight and higher temperatures. In favorable storage conditions (proper container, away from direct sunlight, temperatures between 15 and 65°F), DEF can maintain its qualities for about 12 months. 

Be Good to DEF

Handle it like fuel. Per EPA guidelines, vehicles using DEF must include sensors to continually analyze the quality of the DEF being consumed. These sensors will trigger a fault code whenever an imbalance is detected. Most commonly, this results from a higher percentage of water as a result of foreign matter, condensation or rainwater in the DEF storage container or during transfer.  The quality and integrity of DEF must be maintained for proper machine operation. It must be protected against evaporation and temperature extremes, and kept free of contaminants. Doing so could change DEF density, impacting its performance.

At what temperature does DEF freeze?

DEF Freezing

DEF, because of the urea, doesn’t have the freezing point of water. The urea mixture has a much lower freezing point of 12°F/-11°C. This solution doesn’t break into just urea and just water, either. The solution freezes at the same rate, and also thaws at the same rate. This means that at no point does the DEF freezing cause the solution to become over concentrated or diluted. DEF will begin to slush and then freeze.  There is no harm to the product which means that the urea solution is still safe to use if it has been frozen.

DEF Freezing and Expansion

Though it is safe to use again once thawed, expansion from freezing could cause problems.  Since DEF is a mixture of deionized water and urea, it reacts somewhat like water in that it does expand when frozen. DEF freezing usually causes about a 7% expansion. It is important to note that DEF freezing is usually taken into account when creating the packaging and tanks that are supposed to hold DEF. DEF packaging and tanks allow for expansion. However, one must be aware of the expansion of DEF when filling.  When storing equipment overnight or longer in temperatures that could result in DEF freezing, it is important to make sure the DEF tank on the equipment is not completely full or that it has an appropriate heat source. This will allow for expansion and help prevent cracking of the storage reservoir.

How to Prevent DEF Freezing?

DEF freezing was taken into account by the OEMs prior to creating the Selective Catalytic Reduction (SCR) systems. Therefore, the SCR systems are designed to provide heating for the DEF tank and supply lines; however, if the vehicle is shut down and exposed to freezing temperatures, then it is likely that the DEF will freeze. Diesel owners do not need to worry about DEF interfering with their vehicle, however. If DEF freezes when the vehicle is shutdown, startup and normal operation of the vehicle will not be inhibited. In most cases, the SCR heating system will quickly thaw the DEF in order to return it to liquid form and resume normal operation.


Can Anything Be Added to Prevent DEF Freezing?

Many want to know if anti-gelling or freeze-point-improver can be added to the DEF mixture to prevent freezing. DO NOT put additives into the urea solution because DEF must remain pure. The quality of DEF is extremely important for proper performance. Adding any additives would damage its ability to perform correctly and could even result in damages to the SCR system. No additives are approved for DEF at this time.

DEF Tote Heaters from Powerblanket

Powerblanket has a solution for DEF freeze prevention:  Powerblanket DEF Tote Heaters maintain optimal heating conditions for temperature sensitive materials.  Powerblanket DEF Tote Heaters are temperature specific for the Diesel Exhaust Fluid to protect from freezing and maintain optimal temperatures.

DEF FreezingHere’s How

  • Distribute heat evenly around the tote
  • Fully enclose and heat the tote and pump housing unit
  • Designed to be durable and weather resistant
  • Easy access to fill with a removable top
  • Simple plug and play operation, temperature is automatically regulated
  • Safely heat and protect a wide variety of chemicals and materials
  • 330 and 275  gallon versions feature an easy to access flap to the pump
  • Heated wraps for customized DEF bulk storage tanks available upon request
  • Include a frame to easily enclose and heat pump and hose


Learn More About DEF Totes

The Powerblanket DEF tank heater is the most efficient and effective way to heat and store diesel exhaust fluid.

Keep Propane Tanks from Freezing with a Propane Tank Heater

If you rely on propane for year-round operations, then you already know what a headache winter weather can be. If you have a cold propane tank as a result of dropping temperatures, you’re going to lose a lot of efficiency. Thankfully, there’s a simple solution to keeping your propane tank from freezing, and the solution is something some refer to as a propane tank blanket.


thousand gallon propane tank

Propane Performs Best Under Heat

Did you know that propane can freeze up completely if the ambient temperature drops below -44° F? Granted, -44° F is pretty darn cold, but in terms of gases, it’s a rather high freezing point. As cold as this temperature is in general terms, there are regions North America that experience extremes within this range and even lower, and if you operate a propane tank under these conditions without freeze protection, catastrophe is inevitable.

Worst-case scenario aside, propane tank efficiency will fall substantially as the temperature drops, even if it never plummets as low as -44° F. As the temperature drops, so does the pressure in your propane tank, and the pressure in your propane tank coincides with the volume of propane you have to work with. As pressure drops, not only will the volume of your propane deplete, but your extraction rate (how quickly and smoothly you can extract propane from the tank) will suffer as well. If you don’t have a heating source to assist in the pressure maintenance of your tank, then you’re going to have to keep it as full as possible in order to keep it working, even if temperatures are mildly cold.


Keep Propane Tanks from Freezing with a Propane Tank Heater

More On Propane Extraction or Pressure Rate

Cold weather is the most common dilemma facing propane tank failure, but it isn’t the only one. Another cause of propane tank freezing has to do with the rate of extraction, or the pressure rate. If you’re drawing out a substantial amount of propane from your tank in a short amount of time, then you could cause the tank to freeze and ice up. This is assuming, of course, that you don’t have a heat source to assist with the problem.

Filling your propane tank more often isn’t going to solve a problem like this. And to be quite frank, it’s only a Band-Aid for cold weather dilemmas as well. No, the only real solution to both problems mentioned here is to keep your tank at the ideal temperature, regardless of outside forces. The safest, most efficient way to do this is to employ an external heating system that both insulates your tank and adds regulated and controlled heat to the exterior service.

In the case of heating propane, SAFETY IS MOST IMPORTANT. Propane, as we’re sure you know, is a highly flammable gas, so using any old make-shift solution isn’t safe. On the other hand, using a heating solution design specifically for the process, one that is certified and pronounced safe by reputable, third-party testing laboratories is the only way to go. With that said, let us introduce you to the Powerblanket Propane Tank Heater.



Powerblanket Propane Tank Heater

Powerblanket has the best propane tank heating solution on the market. And we aren’t just saying that because we are Powerblanket. No, we’re saying it because we know of no other company that puts more thought, time, and testing into such a product offering.  Our heating blankets will help maintain pressure and efficiency on just about any size tank.

What’s more, if your tank isn’t the common propane unit, well, that’s no problem. Our custom approach to heating solutions can tailor a blanket to fit your specific dimensions and needs. In addition to this, and most importantly, our product is safe! All Powerblanket heating blankets are certified with ETL certification to the highest standards of safety and efficiency.

Keep Propane Tanks from Freezing

Benefits of Powerblanket Propane Tank Heaters:

  • Increase performance and efficiency of propane tanks
  • Provide even heat distribution
  • Save money by optimizing gas and material usage
  • Safety certified by UL/CSA/CE
  • Eliminates unnecessary cylinder refills in cold weather



Learn more about how to care for your propane tanks with our complete propane guide:

Propane Tank Guide

Keep your propane tanks at the perfect pressure with Powerblanket.