A DEF tank’s capacity can vary based on the make, model, and purpose of a vehicle. Diesel Exhaust Fluid is used in modern diesel engines to reduce harmful nitrogen oxide (NOx) emissions. It’s an aqueous urea solution made with 32.5% urea and 67.5% deionized water.
The size of a DEF tank typically corresponds to the vehicle’s fuel efficiency and its size. For instance:
- Passenger Vehicles and Small SUVs: Many passenger diesel vehicles equipped with a DEF system have smaller tanks, typically ranging between 5 to 20 litres. This ensures the vehicle can travel a significant distance before requiring a refill, sometimes aligning with oil change intervals.
- Pickup Trucks and Larger SUVs: These vehicles tend to have a bit larger tanks. Common sizes for these kinds of vehicles are between 15 to 30 litres.
- Commercial Trucks: These vehicles, designed for long-haul purposes, have the largest tanks. They typically range from 75 to 150 litres, but in some cases, they may even be larger.
- Buses and Coaches: Similar to commercial trucks, these vehicles require larger tanks due to their size and the distances they cover. They can have tanks ranging from 60 to 150 litres.
- Agricultural and Construction Equipment: These heavy-duty machines might have varying tank sizes based on the manufacturer and the intended use of the equipment. Their tanks can range from 20 to 100 litres or more.
There isn’t a fixed size for a tank, and the capacity can range from as little as 5 litres in small passenger vehicles to over 150 litres in heavy-duty trucks and buses. The size is determined by the vehicle’s application, size, and expected range between refills.
Read this related article: Will DEF Lower My Fuel Mileage? (It Improves This Much)
How Much DEF is in a Tank of Diesel?
Diesel Exhaust Fluid and diesel fuel are two distinct fluids, and they are stored in separate tanks in vehicles. So, there isn’t any DEF mixed in a tank of diesel.
However, the rate at which DEF is consumed in relation to diesel fuel can provide some context. Generally, for modern diesel engines that use Selective Catalytic Reduction (SCR) systems to reduce NOx emissions, the average consumption rate of DEF is between 2% to 5% of diesel fuel consumption.
To illustrate, for every 100 liters of diesel fuel a vehicle consumes, it will use approximately 2 to 5 liters of diesel exhaust fluid. But it’s important to note that this ratio can vary based on the engine’s operation, load, engine tuning, and other factors.
So, if you’re trying to estimate how much diesel exhaust fluid might be used on a journey, you would need to consider how much diesel you expect the vehicle to consume and then calculate the corresponding fluid usage based on the typical consumption rate. However, remember that diesel and DEF are stored in separate tanks, and the tank will need to be refilled independently of the diesel fuel tank.
Factors Determining DEF Tank Size
The size of a vehicle’s tank is not arbitrary. Several factors play into determining how large or small the tank should be. Here’s a closer look at these determining factors:
Vehicle Type and Size:
- Passenger Vehicles: Most passenger diesel vehicles have relatively smaller tanks. This is because their diesel consumption rates are lower, and they don’t need a large reservoir to meet emission standards.
- Commercial Trucks: Given that these vehicles are designed for long-haul purposes and consume larger amounts of diesel, they naturally require larger DEF tanks to ensure they can cover significant distances without needing frequent refills.
- Agricultural Machinery: Tractors and other farming equipment may have varying tank sizes, often larger than standard passenger vehicles due to the extended operation times and larger diesel engines.
The Intended Purpose of the Vehicle:
- Long-haul Driving: Vehicles designed for long-haul trips, like big rigs and some buses, typically have larger DEF tanks. The aim is to reduce the number of stops required to refill the DEF during long journeys.
- City Driving: Vehicles predominantly used for city driving or shorter routes, like many delivery trucks or city buses, may have medium-sized DEF tanks. Their frequent stops offer more opportunities to refill if needed.
- Agricultural Use: As mentioned, farming equipment might require larger tanks due to the nature of agricultural tasks. These machines often run for extended periods, and having a sizable tank ensures that tasks aren’t interrupted frequently for refills.
Manufacturer Specifications and Design Choices:
Integration with Vehicle Design: Some vehicle designs might allow for larger or smaller DEF tanks depending on the available space and the overall design of the vehicle.
- Consumer Preferences: Manufacturers may also consider the convenience of the end-user. A larger tank can be a selling point for those who wish to have fewer maintenance stops.
- Cost Considerations: Building a vehicle with a larger tank may increase the production cost slightly. Manufacturers have to balance the cost with the benefits and the target market’s demands.
The size of a tank isn’t a one-size-fits-all scenario. Multiple factors, from the vehicle’s type and its primary use to the manufacturer’s design choices and market strategy, all influence the tank’s size. As consumers become more educated about the importance of DEF, its tank size will continue to be a consideration for many when purchasing a diesel vehicle.
Conclusion
The capacity of a DEF tank isn’t a uniform measurement, as it’s tailored to the unique requirements and designs of different vehicles.
Whether it’s a compact passenger car or a mammoth long-haul truck, the size of the tank is a testament to the balance between engineering needs, consumer convenience, and environmental considerations. While understanding the specific liters a DEF tank holds might seem like a minor detail, it reflects the larger effort of the automotive industry to reduce harmful emissions and promote eco-friendly driving.
As diesel vehicles continue to evolve and adapt to stringent environmental standards, the role and design of the tank will undoubtedly be part of this journey.
For now, vehicle owners and operators should be attuned to their consumption and ensure they understand their vehicle’s needs, ensuring efficient operation and reduced environmental impact.