What’s That: Closed Loop DEF System

If you manage a fleet of trucks, you know your DEF purchase is just as valuable as your fuel. But DEF is only as effective when it’s stored, maintained, and dispensed properly. Your equipment and storage setups directly impact operational efficiency, and it’s important to use systems tailored to your specific business needs.

For operations managers focused on uptime, engine health, and lowering total cost of ownership, one feature can make a major difference: choosing a closed loop DEF system. In high-traffic and high-dust environments like construction, closed-loop systems help protect DEF purity by preventing dirt, dust, and other contaminants from entering the tank during transfers.

What’s a Closed-Loop DEF System?

A closed-loop system is a sealed transfer system that allows DEF to move from storage (like totes, drums, or bulk tanks) directly into the vehicle without exposure to outside air or contaminants. It’s designed to prevent contamination during the storage, transfer, and dispensing of DEF. Think of a closed-loop system as a no-touch environment, where the DEF never sees the light of day.

The main part of the system is the sealed coupler that connects dispensing equipment to DEF containers and vehicle tanks. This airtight, spill-proof connection prevents dirt, dust, or metal particles from entering the fluid. Unlike jugs or open containers that allow air to flow into the DEF tank, close-loop tanks are sealed – a necessary safeguard, considering how sensitive Selective Catalytic Reduction (SCR) systems are to impurities. In dusty environments, closed-loop systems help prevent airborne contaminants from entering during DEF transfer, protecting both your equipment and your bottom line.

Why It Matters to Your Fleet

DEF is nonnegotiable in fleet operations. As a regulated product, it must meet ISO 22241 standards to ensure emissions compliance and protect your SCR system from costly damage. But simply incorporating DEF isn’t enough. You also need to handle it efficiently and properly to combat contamination. Poor handling can quickly lead to expensive repairs to the SCR system.

Contaminated or degraded DEF can cause:

• Damage to the SCR catalyst
• Engine to derate or shutdown
• Check engine lights and fault codes
• Damaged sensors or injectors
• Fines for non-compliance

Most of these issues stem from improper handling, especially in open systems where DEF is manually poured from unsealed containers. Open systems increase the risk of contamination, spills, and inconsistent performance. Alternatively, a closed-loop DEF system eliminates that risk. It keeps DEF sealed from storage to dispense, reducing evaporation, preventing contamination, and ensuring clean, consistent DEF delivery across your fleet. The result? Fewer surprises, less downtime, and more time keeping your fleet on the move.

Making the Switch? We’ll Help You Get There

If you’re using open containers, we’re here to help you upgrade to a safer, compliant solution. At Mansfield, we make upgrading simple. Our team of experts will walk you through your options, assess your current site setup, and recommend a solution that fits your fueling volume, equipment needs, and space constraints.

Our DEF offerings include:

• Bulk DEF Delivery: Get high-quality, API-certified DEF delivered straight to your site.
• Closed-Loop Tote & Drum Systems: We offer DEF totes and drums with secure closed-loop valves, plus pump kits for safe, efficient transfer.
• On-Site Storage Tanks: For high-volume operations, our DEF storage tanks and dispensing systems integrate seamlessly with your fuel supply.

We also provide on-site training, so your team knows exactly how to use and maintain your new DEF system. As emissions standards tighten and diesel technologies evolve, DEF quality control is a necessity. A closed-loop system is your first line of defense against costly contamination and unplanned downtime. Ready to upgrade your DEF system? Reach out to our team today and take a look at our online catalog!

FUELSCast

Want to learn more about DEF? Tune into this episode of FuelsCast, “Discover the Industry’s Best-Kept Sustainability Secret,” where we break down the basics, benefits, and big impact of Diesel Exhaust Fluid on today’s engines and emissions standards.

Click here to watch the episode!