Introduction: What is DEF?

Diesel exhaust fluid (DEF) is a non-toxic mixture of urea and deionized water. In 2010, the Environmental Protection Agency (EPA) introduced DEF as part of the Clean Air Act, a comprehensive Federal law regulating the different sources of pollution and their fuels. Selective Catalytic Reduction (SCR) systems use DEF to reduce the harmful emissions diesel engines can release during operation.

Effectively storing DEF fluid is a critical part of controlling emissions and reducing environmental impact, especially in the automotive and construction industries. Today’s engines require a reliable supply of DEF to function properly and will eventually shut down if users do not maintain proper fluid levels.

DEF is not a fuel additive and is typically stored in a separate tank to maintain purity. However, questions and concerns may remain about storing DEF onsite. Learn more about DEF storage requirements in this definitive guide, including best practices and proper handling techniques.

DEF Fluid Storage: Best Practices

As a non-toxic substance, DEF does not follow the same regulatory standards as fuel. However, there are still industry guidelines to follow for safe storage and handling. ISO 2224 outlines storage requirements and is the standard for handling, manufacturing, and transporting DEF.

Consider the following when storing DEF fluid:

Minimize Contamination.
Separate DEF from other chemicals and fuels to reduce the risk of cross-contamination. Choose an isolated area with minimal surface water drains.
Avoid Direct Sunlight.
Keep DEF away from direct sunlight. This helps maintain the potency of urea content in your fluid.
Maintain Your Equipment.
Routinely clean equipment, machinery, and dispensing nozzles to minimize the risk of crystallization.
Use a Dedicated Pumping System.
Avoid mixing DEF with other fuels and only use dedicated DEF pumping systems.
Avoid Overfilling Your DEF Tank.
DEF fluid can corrode some metals, especially if it spills over and comes into contact with other metals. Utilize a steel storage tank with a secondary containment system to safely store your DEF fluid.

DEF Storage: Frequently Asked Questions (FAQs)

At Krueger Sentry Gauge, we have experience addressing a range of questions and concerns about DEF storage requirements. The most common questions we get include:

What Is the Shelf Life of DEF What Is the Shelf Life of DEF?
While DEF typically lasts one to two years, it can vary depending on storage conditions. Once DEF fluid expires, it loses effectiveness and can seriously damage equipment and machinery. It’s important to monitor the quality of DEF fluid to minimize contamination and help equipment perform at its best.
What Temperature Does DEF Freeze What Temperature Does DEF Freeze?
DEF’s freezing point is -12 ºF (-24.4 ºC). DEF liquid can expand up to 7% when frozen and damage a storage tank, particularly when it is full. While certain additives may keep DEF from freezing, they can also negatively impact the fluid’s effectiveness and purity. If you let DEF thaw naturally, you should still be able to use it.
Why DEF Storage Requirements Matter

Why DEF Storage Requirements Matter

DEF storage requirements address a growing need to safely store large quantities of DEF. This includes reducing the emissions of harmful substances produced when burning diesel fuel.

A common example is nitrogen oxide (NOx), a byproduct of diesel fuel that pollutes the air and contributes to asthma, heart and respiratory diseases, and smog. In this case, compressed air in the cylinders causes high frictional heat levels and can ignite diesel fuel without a spark. This is different from a gasoline engine, which uses a spark to ignite and burn fuel.

Following DEF storage requirements provides additional benefits such as:

  • Prolonged shelf life of fluid
  • Compliance with DEF regulations
  • Minimized contamination
  • Reduced risk of fire
  • Higher performance ratings for off-road vehicles, equipment, and machinery

DEF Gauges: How They Promote Compliance

Liquid level DEF gauges measure the volume of liquid inside tanks and drums. These level indicators can provide accurate readings in applications where fluids such as chemicals, waste, and DEF are not visible or are too dangerous to handle.

Float material, rod material, and the types of fluid they operate in are crucial factors to consider when selecting a compatible liquid-level gauge. Krueger Sentry Gauge offers state-of-the-art DEF level gauges with stainless floats, brushings, and rods.

DEF Fluid Gauge Measurement Best Practices

Test for UREA Concentration DEF Fluid Gauge Measurement Best Practices

Test for UREA Concentration

A DEF gauge or handheld refractometer can quickly measure fluid concentration. The target for the percentage of urea content is 32.5% with an acceptable range of 31.8% to 33.2%.

Dirt or Metal Contamination DEF Fluid Gauge Measurement Best Practices

Test for Dirt/Metal Contamination

DEF is clear by nature. If your DEF fluid looks colored or cloudy, it may be expired or contaminated. Visually inspect your DEF storage containers and filters for metal or dirt debris.

The Insoluble Matter Test (<20 ppm max) checks for DEF contamination. DEF fluid should also meet the ISO 22241 standard for cleanliness. OEMs can use ISO Particle Counts to test for contamination. Look for a result of 18/16/13 or lower.

Test for Other Fluids DEF Fluid Gauge Measurement Best Practices

Test for Other Fluids

Diesel fuel can contaminate DEF fluid and cause engine issues over time. However, a simple smell test can confirm the presence of various contaminants.

Antifreeze can also contaminate DEF fluid and drastically alter its urea concentration. Collecting a test sample from the top fluid layer of a DEF storage tank can accurately identify engine or hydraulic oil contamination.

High-Quality DEF Gauges by Krueger Sentry Gauge

For over 80 years, Krueger Sentry Gauge has provided liquid-level tank gauges for various industries and applications. Our DEF fluid gauges offer unsurpassed quality, accuracy, and dependability. We use our vast industry experience to develop solutions that meet specific DEF storage requirements, ensuring the safety and viability of your products.

Contact us today to learn more about our DEF gauges and find a product that meets the demands of your particular project.