DEF FREQUENTLY ASKED QUESTIONS

Q. WHAT IS DIESEL EXHAUST FLUID, OR DEF?
A. Diesel Exhaust Fluid (DEF) is a reactant that’s key to the SCR process. It’s a nontoxic, aqueous solution of 32.5% urea and 67.5% water. To assure quality, DEF should be purchased only from a certified supplier.
Q. WHAT IS UREA?
A. Urea is a compound of nitrogen that turns to ammonia when heated. It is used in a variety of industries, perhaps most commonly as a fertilizer in agriculture. Urea is often added to hand and foot creams.
Q. HOW MUCH DEF WILL BE REQUIRED?
A. DEF is injected only when needed. Consumption will be approximately 2% of fuel consumption, depending on how and where you operate your motorcoach (duty cycle, passenger capacity, terrain, etc.).
Q. HOW MAY MILES CAN A MOTORCOACH TRAVEL ON A SINGLE GALLON OF DEF?
A. Again, DEF consumption is related to fuel consumption. A motorcoach averaging 7 MPG will be able to travel 233 miles or more on one gallon of DEF (U.S. gallons).
Q. HOW MUCH WILL I PAY FOR DEF?
A. At the time DEF goes on sale, it is anticipated that pricing will be at or below the cost of diesel fuel.
Q. HOW DOES OUTSIDE TEMPERATURE AFFECT DEF?
A. DEF will begin to form a frozen slush at -11º C /12º F. When the engine is running, the vehicle coolant system provides heating for the DEF tank and supply lines. DEF thaws very quickly. If it freezes when the motorcoach is not operating, start-up and normal operation of the vehicle will not be affected. The vehicle coolant system will heat the DEF to liquid form and vehicle operation can continue normally. When frozen, DEF expands by about 7%. DEF tanks are designed to accommodate this expansion.
Q. WHAT HAPPENS IF A DRIVER RUNS OUT OF DEF?
A. DEF indicators on the dash will alert the driver regarding DEF status. A gauge much like a fuel gauge will indicate the level of DEF in the tank. A DEF low-level warning will activate when the DEF tank is low. If a driver runs out of DEF completely, vehicle power will be reduced to derate mode. When the DEF tank is refilled, the engine will resume normal power. Error codes will be logged into the computer for future analysis of operation history.

Q. HOW SHOULD DEF BE STORED?
A. Store DEF in a cool, dry and ventilated area, away from direct sunlight. Recommended storage temperature is up to 25º C /77º F, though brief exposure to higher temperatures will not be a problem.
Q. WHAT IS THE SHELF LIFE OF DEF?
A. This is largely a factor of storage temperature. DEF degrades over time depending on temperature and exposure to sunlight. If stored at recommended temperatures (not exceeding 25º C /77º F) shelf life will be around two years.
Q. ARE THERE ANY HANDLING CONCERNS WITH DEF?
A. DEF is nontoxic, nonhazardous and nonflammable. It is nonpolluting and meets strict international standards for purity and composition. DEF poses no serious risk to drivers or equipment when handled properly. Always buy DEF from a certified supplier. Always keep DEF in original certified containers. To prevent contamination and damage to the filter or pump, do not transfer DEF to other containers. Be sure to add DEF to the DEF tank only—do not add DEF to oil, coolant, gas or other tanks.
Q. IS DEF CORROSIVE?
A. DEF is corrosive to steel, copper, aluminum and lowergrade plastics or plastics with additives in them. DEF tanks and dispensing equipment are made of heavy-duty plastic with no additives.
Q. HOW DOES DEF AFFECT SERVICE AND MAINTENANCE?
A. Coaches with a Volvo SCR system require no change to service and maintenance intervals. The DEF filter can be changed in minutes.
Q. HOW IS DEF PACKAGED?
A. DEF will be available in 2.5-gallon containers, 55-gallon drums, 275-gallon IBC and in bulk storage for fleet locations, truck stops and dealerships.
Q. WHERE WILL DEF BE AVAILABLE?
A. DEF will be everywhere drivers are. All major truck stops, dealers and distributors will carry DEF.