Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/370987
water. Unlike fuel or lube oils, manu- facturers can't put additives in DEF to make it better or different from any other manufacturers, so it is treated as a commodity, says Van Wyk. 2. How much DEF do I need? As a rule of thumb, off-road ma- chines will consume an amount of DEF equal to roughly 2 to 10 percent of the fuel you burn. How much DEF your Tier 4 Final machines consume depends primarily on who makes the en- gine. Emissions reduction in Tier 4 Final engines is a balance between selective catalytic reduction (SCR) which uses DEF, and exhaust gas recirculation (EGR). The more DEF an engine uses the less EGR it needs. The more EGR, the less DEF. Deere's engines are de- signed for more EGR, less DEF consumption and will consume between 1 and 3 percent DEF relative to the fuel burned, says Andrew Kahler, product market- ing manager, engines and drivelines at Deere. "If you go to the middle of that, around 2 percent, that's where most of our machines are running," he says. In that scenario a machine that burns 150 gallons of diesel a month, burning 2 percent DEF would mean you need plan for 3 gallons of DEF a month for that machine. Many engines with European roots, such as Case, are designed to burn more DEF, as much as 10 or even 12 percent DEF relative to the diesel con- sumed. Philippe Bisson, brand manager Case Con- struction Equipment, says the SCR-only system used in that company's dozers and wheel loaders brings a 10-percent improvement in fuel efficiency, lower component costs and other benefits. Since each OEM will have a dif- ferent engine design it's a good idea to conduct some due dili- gence and talk with your dealers about what many are now calling the overall "fluid consumption rates," meaning the combined con- sumption of diesel and DEF. You'll need to know this to develop ac- curate owning and operating cost figures for Tier 4 Final machines. Temperature and humidity also affect DEF consumption although to a very small extent, says Kahler. Hot and dry climates will result in greater DEF consump- tion. Cold and humid environ- ments require less. To plan for future DEF con- sumption and inventory, you'll need to monitor usage closely for the first few months to develop your own operating cost formulas for each type of machine and ap- plication. "We've educated our dealers so that they don't sell the customer too much DEF," Kahler says. "DEF has a shelf life similar to what you would see in coolants or oils. Not a short shelf life, but we want to make sure customers are consum- ing it within six months to a year." September 2014 | EquipmentWorld.com 20 maintenance | continued Blue is for DEF, green for diesel. They are typically placed side by side so you can refuel both at the same time.