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AdBlue is essential for trucks with SCR catalysts. However, poor handling could result in expensive damage
Words: Sharon Clancy
For Euro-4 and -5 trucks fitted with selective catalyst reduction (SCR) systems, AdBlue is as essential for the smooth running of a vehicle as oil. AdBlue producers are concerned that operators are accidentally risking potentially expensive damage to the SCR system through poor handling and storage of AdBlue and by buying products from non-licensed suppliers. "There has been a general lack of information from the truck industry informing the end user of the importance of ensuring AdBlue is handled correctly," says Chris Haynes, UK managing director of manufacturer Greenchem.
"SCR systems are very sensitive to potential chemical impurities in the urea solution. Even small amounts of impurities can severely damage the performance of the SCR system," warns Paul Norman of AdBlue manufacturer and distributor Air 1 Yara.
AdBlue is essentially a solution of urea in de-ionised water, manufactured to strict purity standards: ISO 22241 and DIN 70070. However, using non-pure water in producing a urea solution is the biggest threat to your catalyst, warns Norman. "There are suppliers that view AdBlue as just urea mixed with water and who offer urea solution often. They don't have an AdBlue licence and the material often doesn't meet the AdBlue standards.
"High levels of calcium can restrict and block a vehicle's catalyst, which is likely to result in poorer fuel consumption, even before any possible resultant and costly vehicle damage. Vehicle manufacturers are unlikely to support warranty claims if it is discovered that a poor-quality urea solution or contaminated AdBlue is the cause," Haynes says.
Contamination The bad news is that having bought AdBlue from a licensed supplier, it is easy for an AdBlue solution to become contaminated in storage or during dispensing. Urea is mildly corrosive, so will attack metal, while de-ionised water in AdBlue can attract ions from other materials it comes into contact with, including some plastics and even glass.
Workshop and refuelling practices can also lead to accidental contamination, says Martin Flach, Iveco product director. "The classic mistake is to use any handy container or jug to top-up the AdBlue tank on the vehicle, including oil cans and screenwash bottles."
AdBlue tank seals are not tolerant of mineral oil, he says, so will need replacing early. "More costly can be premature SCR failures, which occur as metals from corroded pump parts get into the system."
Manufacturers have taken steps to prevent drivers or workshop staff accidentally topping up the AdBlue tank with diesel with special nozzles, but cross-contamination still happens, says Tim Griffiths, product manager at Greenox AdBlue, manufactured by Tennants. "It is possible to clean the tank and replace the seals, but the dosing pump, injectors and the catalyst on the vehicle might need replacing," he says.
Mercedes-Benz says that NOx sensors in the exhaust will react to contamination in a similar way to a lack of any AdBlue: initially increasing the AdBlue dosage to bring NOx levels down and, eventually, by reducing torque and power. The engine management system will be recording this data, so if consumption rises in AdBlue it could be an early indication of contamination problems, says the company.
Storage
AdBlue shelf life varies from six months, but it can be extended to up to 18 months in ideal storage conditions. Direct sunlight and temperatures above 30°C cause it to breakdown and lose its effectiveness. AdBlue freezes at -11°C, so insulation protection is advisable. "We recommend IBCs are stored under cover because sunlight weakens the AdBlue solution. It will still be usable, but the consumption rate will increase," says Griffiths.
AdBlue is not a hazardous substance, so it does not legally require bunded storage. However, urea is polluting to ground water and the Environment Agency has published advice on AdBlue storage.
It says urea can corrode pipes as well as tanks, and that oil-separator systems are not effective at catching any AdBlue spills.
"A bunded system incorporating all pipework and dispensing equipment provides insulation for the product and prevents any spills polluting ground water," says Kevin Powell, sales director at bulk storage tank manufacturer Ledbury Welding and Engineering. "The inner tank can be high-density polyurethane plastic or stainless steel to prevent contamination, with an outer tank of mild steel. A plastic inner tank is more economical, but stainless steel can be fabricated to suit the storage space available."
AdBlue storage tanks come in a range of sizes, from forecourt topping-up cans to 20,000-litre-plus fixed tanks. Suppliers report that 1,000-litre IBCs are popular with UK operators. The three main UK suppliers of AdBlue (Greenchem, Air 1 Yara and Tennants) all offer a supply-and-collect service, swapping the empty IBC for a full one, which reduces the risk of contamination. IBCs and larger bulk storage tanks can be supplied with telemetry equipment that automatically alerts the supplier when stocks are low.
Dispensing equipment
Multi-purpose dispensing pumps and equipment will also contaminate AdBlue, warn manufacturers. "Stainless-steel fittings, including valves and nozzles, are essential," says Griffiths, "while flow meters and nozzles with automatic shut-offs will help avoid over-filling and spills." •
Further information Air 1 Yara www.air1info.com; tel.: 0700 4232 583 Greenchem Solutions www.GreenChem-adblue.com; tel.: 01296 468531 Tennants www.tennantsdistribution.com; tel 0161 305 1,454 (England & Wales); 01698 717 900 (Scotland); 02890 455 135 (Northern Ireland)
Environment Agency
www.environment-agency.gov.uk
Ledbury Welding www.tweltd.co.uk; tel: 01531 632222
DOs AND DON'Ts
• Source the AdBlue only from licensed suppliers that will supply urea to ISO 22241or DIN70070 standard.
• Check storage equipment is made from inert materials that will not contaminate the AdBlue.
• Use recommended materials for dispensing equipment and keep it clean.
DON'T...
• Use existing mild steel or plastic tanks or containers for storing AdBlue.
• Use canisters, jugs or bottles that have been used for screenwash or oil to refill vehicle AdBlue tanks.
• Allow dirt and moisture in the environment to enter storage tanks or dispensing receptacles.
• Allow AdBlue spills to contaminate ground water system.
• Use out-of-date product: consumption rates will increase and damage to the SCR system may occur.