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Diesel Exhaust Liquid Specialists

Frequently Asked Questions

Health and Safety

What Safety concerns should I be aware of?

Diesel Exhaust Fuel (DEF) is not classified as dangerous according to the Australian standard NOHSC1008. Optiblues DEF is a 32.5% solution of high-purity urea in de-mineralized water that is clear, non-toxic and safe to handle.It is non explosive, non-flammable nor harmful to the environment. DEF is classified under the minimum risk category of transportable fluids. It is not a fuel, nor a fuel additive and needs to be used in a dedicated tank in your heavy-duty vehicle. It is replenished in a similar way as to refuelling diesel.

Should you spill DEF on your hands, simply wash it off with water.

Is Diesel Exhaust Fluid (DEF) corrosive?

Diesel Exhaust Fluid (DEF) is not toxic, harmful or dangerous. In fact, of all the fluids used in a truck, such as diesel, engine oil, brake fluid, antifreeze and windscreen wash, DEF is the least hazardous. However, DEF is corrosive for some metals such as carbon steel, aluminium, copper and zinc, and DEF should not be stored in containers made of these materials. Your DEF supplier can advise you further.

Do I need to wear protective clothing when filling up the DEF tank?

Wearing protective clothing is not necessary when handling DEF, however, Diesel Exhaust Fluid (DEF) can stain clothes. If you do spill any DEF on your clothing, rinse it off with water.

What should I do if a spill DEF?

If you spill a small amount of Diesel Exhaust Fluid (DEF), it can be washed away with water or wiped up. If you leave it to dry it will turn into white crystals. These can be washed away with water. If you spill a large amount of DEF then contact your DEF supplier for advice.





Where can I buy Diesel Exhaust Fluid (DEF)?

Optiblue can supply all your DEF needs and have trucks that can delivery DEF to your doorstep.

How much of Optiblues Diesel Exhaust Fluid will be consumed by my vehicles?

Average consumption is generally around 5% of diesel use. This equates to around 5 litres of DEF for every 100 litres of diesel.

How should Optiblues DEF be stored?

Diesel Exhaust Fluid should be stored away from direct sun light in a dedicated tank. It retains its potency for 1 year. It needs to be protected from too warm or too cold temperatures.Its freezing point is at -11 degrees Celsius. It should be stored in a sealed package and in a well ventilated storage area.

What is Selective Catalytic Reduction?

Selective catalytic reduction (SCR) is a means of converting nitrogen oxides, also referred to as NOx, with the aid of a catalyst into diatomic nitrogen, N2, and water, H2O.A gaseous reductant, typically anhydrous ammonia, aqueous ammonia or urea (OptiBlue/DEF), is added to a stream of fuel or exhaust gas and is adsorbed onto a catalyst. Carbon dioxide, CO2 is a reaction product when urea is used as the reductant.Commercial selective catalytic reduction systems are typically found on large utility boilers, industrial boilers, and municipal solid waste boilers and have been shown to reduce NOx by 70-95%.

More recent applications include diesel engines, such as those found on large ships, diesel locomotives, gas turbines, trucks and automobiles.

What is Selective Catalytic Reduction (SCR) technology for on-road and off-road diesel powered vehicles?

Diesel Exhaust Fluid is combined with SCR technology.  SCR stands for an after treatment technology called Selective Catalytic Reduction. This technology requires the use of an operating fluid known as Diesel Exhaust Fluid (DEF) to reduce the Nitrogen Oxides (NOx) in the emissions.  Almost all major diesel engine manufacturers have decided to use this SCR technology to meet the new emission regulations on NOx reduction. SCR is the most cost effective solution to meet NOx emission standards of the EPA Clean Air Act.

The main components of the SCR system are the SCR catalyst, the Diesel Exhaust Fluid injection unit, the Diesel Exhaust Fluid tank and the DEF dosing control unit. Diesel Exhaust Fluid is injected into the exhaust pipe, in front of the SCR catalyst, downstream of the engine. The heat of the engine exhaust gases decomposes DEF into ammonia.  When the NOx reacts inside the catalyst with the ammonia, the harmful NOx molecules in the exhaust are converted to harmless nitrogen and water.

Where can I buy Diesel Exhaust Fluid (DEF)?

Optiblue can supply all your DEF needs and have trucks that can delivery DEF to your doorstep.

How much can I expect to pay for Diesel Exhaust Fluid (DEF)?

The price of Diesel Exhaust Fluid (DEF) will depend on your location, supply method and the volume of fluid that you purchase.

What will happen if my truck runs out of Diesel Exhaust Fluid (DEF)?

DEF is legislated to be used in new vehicles and manufacturers put measures in place to ensure that vehicles cannot run without Diesel Exhaust Fluid (DEF). Before a truck’s DEF tank runs empty the driver is given a series of alerts on their dashboard displays (much the same way as if they were running low on diesel). Generally speaking, when the DEF tank level drops below 20% an amber warning lamp will come on and if the tank level drops further the truck will go into limp mode.

Is there any danger of filling the Diesel Exhaust Fluid (DEF) tank with diesel and what problems will it cause?

There are a number of safeguards put in place to prevent confusion between diesel and Diesel Exhaust Fluid (DEF) filler necks. The standard nozzle diameter for DEF is 0.75 inches (19mm), compared to 0.87 inches (22 mm) for diesel, preventing the diesel nozzle from ever being inserted into the DEF tank. In addition, the filling cap for the DEF tank is blue and will be clearly marked ‘Diesel Exhaust Fluid’ with the accompanying ISO standard number.

However, a small number of cases have been reported where diesel has been put in the DEF tank. Diesel is less dense than DEF and will float on top of the DEF in the tank, but even small amounts of diesel can damage your SCR system and we recommend that you contact your dealer immediately and do not drive the vehicle.

If DEF or AdBlue is filled into the diesel tank, the engine will stop running almost immediately, and the vehicle will need to be taken to a service centre for repair.

If I switch Diesel Exhaust Fluid (DEF) suppliers, what should I do with the fluid which remains in bulk storage tanks and do I need to have them cleaned out?

No, simply run the tank as empty as possible before refilling. Diesel Exhaust Fluid (DEF) is a pure chemical, so your bulk storage tank does not need to be cleaned out unless it is contaminated. DEF from different certified suppliers can be mixed.

What fuel saving can I expect from a truck equipped with Selective Catalytic Reduction (SCR) technology?

Selective Catalytic Reduction (SCR) is an after treatment emissions control technology, which deals with emissions outside of the engine. This means manufacturers are able to tune engines to boost performance and achieve fuel savings. The extent of these savings will vary, but fleets’ experiences with post 2010 heavy-duty trucks suggests fuel savings of around 5% compared to 2007 models with similar engine specifications.

When was Selective Catalytic Reduction (SCR) technology first used?

Selective Catalytic Reduction (SCR) technology was first patented in 1957 and has been used for many years to reduce NOx emissions from coal-fired power plants and other stationary sources. The technology was first used in series production in diesel vehicles by Nissan Diesel in Japan in 2004 to meet emissions standards that were the strictest in the world at that time. Since then SCR has been widely implemented worldwide on diesel vehicles and by the end of 2012 more than one million commercial vehicles were equipped with SCR emissions control technology in Europe alone.

What is the shelf life of Diesel Exhaust Fluid (DEF)?

Diesel Exhaust Fluid (DEF) has a shelf life of two years. However, this can be reduced if the fluid is exposed to direct sunlight or if the temperature of the DEF remains above 86°F (30°C) for sustained periods. All DEF packaging should be labelled with an expiry date. If you have DEF that it beyond its expiry date, contact the supplier for advice, or dilute it with water in a ratio of 1:10 and use it on your lawn!

A large part of Diesel Exhaust Fluid (DEF) is de-ionized water, do I have to worry about the tank or other parts of the Selective Catalytic Reduction (SCR) system freezing?

Diesel Exhaust Fluid (DEF) freezes into a crystalline slush at 12°F (-11°C) and should not be kept at temperatures above 86°F (30°C). If DEF is frozen on your vehicle, for example overnight or over a weekend, you do not need to take any action. Use the vehicle as you normally would. Truck manufacturers use a variety of heating methods to thaw frozen DEF tanks, including in-tank heating elements. While the thawing process is taking place the vehicle’s performance will not be affected (the amount of DEF used will be reduced because a cold engine produces a low level of NOx emissions). In some cases the DEF supply tubes are also heated to prevent freezing or tubes are emptied once the engine is turned off. In short, there is no reason to be concerned about using your SCR truck in cold weather.

Does DEF evaporate, and what happens if it does?

Diesel Exhaust Fluid (DEF) evaporates if stored at higher temperatures for a prolonged period. To avoid any risk of evaporation keep the cap of the DEF tank and storage containers securely closed.

Field tests have shown that even in high temperatures there is no significant risk evaporation from DEF tanks.

  Contact OptiBlue

Optiblue is based in Adelaide, South Australia and our fleet services all states within Australia.

  Telephone: 1300 789 872

OR complete our online enquiry form and we will get back to you.


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