Specialist pipework for Diesel Exhaust Fluid

Specialist pipework for Diesel Exhaust Fluid

David Naylor, our PLX Brand Manager discusses the dangers that can come with the storage and transfer of Diesel Exhaust Fluid for bulk refuelling.

With AdBlue, a trade name for Diesel Exhaust Fluid (DEF), now required by all Euro 6 vehicles, transport operators need reliable storage and transfer solutions to cater for the large volumes required. However, the highly corrosive nature of the fluid is leading Durapipe UK to issue a warning not to take risks with the fuel conveyance systems that are installed.

European emission standards define the acceptable limits for exhaust emissions of vehicles in EU member states, with emissions of nitrogen oxides, total hydrocarbon, non-methane hydrocarbons and carbon monoxide regulated for cars, vans, light commercial vehicles, lorries, trains and tractors.

Since European emission standards were introduced in 1992, they have become ever more stringent with every update. The Euro 6 standard for all diesel cars and light commercial vehicles up to 1,750kg, which came into force in January 2015, requires nitrogen oxide (NOx) emissions to be capped at 80mg/km, an additional reduction of more than 50%, compared with the previous Euro 5 standard. For HGV’s with a diesel engine, the current Euro VI standard stipulates a 0.4 g/kWh limit, a reduction of 400% compared with Euro V limits.

In order to meet the regulations, vehicles are fitted with selective catalytic reduction (SCR) emissions control systems. Carefully metered amounts of DEF are injected into the catalyst within the SCR system, with the heat turning the urea within the DEF into ammonia, which in turns reacts with the NOx in the exhaust gases converting it into nitrogen and water vapour.

Every new vehicle with a diesel engine now requires DEF and so fleet operators have needed to accommodate the large volumes of the substance required to inject into their vehicles. While there are different options for the storage and transfer of DEF, they all require a pipework system to transport the fluid to the refueling dispensers. However, caution needs to be taken as DEF is highly corrosive and could potentially damage equipment and the environment if suitable systems are not installed.

The aqueous urea solution contains 32.5% high purity urea, which will cause corrosion of many metal systems. It is vital that DEF remains clean as contamination of the fluid, through corrosion, could lead to damage of the vehicle engine and / or harmful emissions being released into the atmosphere.

DEF, which is also known as AdBlue or AUS32, can pollute surface and groundwater, while if it remains puddled on concrete for long periods it could also damage surfaces, so appropriate precautions must be taken when storing and dispensing the solution to ensure leaks do not occur.

Due to the corrosive properties of DEF, plastic pipework systems are preferred when conveying the fluid. However, Durapipe UK is advising that not all plastic pipework systems offer the same performance capabilities and transport operators should give careful consideration to the solution being installed. With the use of DEF only set to increase, some manufacturers are looking to cash in on the opportunity and many are marketing existing standard fuel pipe products as suitable for conveying DEF.

At the very least, a dual contained pipe system should be selected to ensure that, if any leaks do occur, they are contained within the system and are not at risk of polluting the atmosphere or damaging the environment and personnel operating the equipment. Ideally, a specially developed solution should be installed, such as Durapipe’s PLX Blue, which has been purpose-designed to safely carry DEF without fear of the additive corroding the pipe wall or leaking into the environment.

Manufactured from a specialised high-grade polyethylene, a superior quality material that is extremely robust, PLX Blue provides exceptional resistance to rapid crack propagation and long term stress cracking. PLX Blue comprises a protective liner, which increases permeation resistance against DEF ensuring there is no permeation of fuel through the pipe wall into the environment. The product’s durable properties also provide a design life of more than 30 years, with little maintenance required during the lifetime of the product.

Damage to fuel equipment and vehicle engines, through the unsafe transportation of DEF, would not only be costly for fleet owners to repair, but could also result in a loss of revenue while vehicles are off the road. DEF will soon be common place for all diesel vehicles in service, so it is important for transport operators to invest in reliable equipment that can assist with the safe and successful operation of transport fleets.


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