PAGE 8 — DEF TANK REPLENISHMENT SYSTEM • OPERATION MANUAL — REV. #0 (09/11/20)
FREQUENTLY ASKED QUESTIONS
WHAT IS DEF?
Diesel Exhaust Fluid (DEF)
is one of the key elements
involved in the selective catalytic reduction (SCR) process.
It is a nontoxic solution of 67.5% deionized water and 32.5%
synthetic automotive grade urea. DEF helps to convert NOx
into nitrogen gas and water vapor. It is stable, colorless,
odorless, and meets accepted international standards for
purity and composition.
WHAT IS AN SCR?
SCR
stands for
Selective Catalytic Reduction
. This
system uses a catalyst in the exhaust system of applicable
diesel engines. It sprays DEF (diesel exhaust fluid) into the
exhaust stream to convert nitrogen oxides (NOx) in the
exhaust into nitrogen and water vapor.
The goal of an SCR system is to reduce levels of NOx
(oxides of nitrogen emitted from engines) that are harmful
to our health and the environment.
SCR is an after-treatment technology that treats exhaust
gas downstream from the engine. Small quantities of
DEF (automotive-grade urea solution) are injected into
the exhaust stream and, when mixed with the NOx, are
changed into harmless nitrogen and water.
WHAT IS UREA?
Urea, also known as carbamide, is an organic compound
of nitrogen that turns into ammonia when heated. It is
used in a variety of industries, including as a fertilizer in
agriculture. Urea is produced from synthetic ammonia and
carbon dioxide.
WHAT IS THE ALLOWABLE TEMPERATURE
RANGE OF DEF?
DEF will begin to freeze at 12°F (–11°C). DEF thaws quickly.
There are optional heating components available for this
unit to assist in cold-weather conditions.
WHAT IS THE SHELF LIFE OF DEF?
The shelf life of DEF is typically at least one year, depending
on the storage temperature. It is best stored out of direct
sunlight between 12°F (–11°C) and 86°F (30°C).
In
cold
temperature regions the DEF temperature will
automatically be controlled by a built-in heating element.
In
warm
temperature environments, it is recommended
that the DEF be stored in a cool area to avoid possible
water evaporation.
IS DEF TOXIC?
No, as compared to other automotive fluids (e.g. diesel fuel,
brake fluid, coolant fluid, and engine, transmission and axle
lube) which are more toxic. The Environmental Protection
Agency classifies DEF as “non-hazardous.” Urea is naturally
occurring and biodegradable.
Non-hazardous
Non-flammable
Non-explosive
Non-toxic
DEF QUALITY
DEF is defined by AUS-32 specifications. The American
Petroleum Institute (API) has developed a quality
certification program to ensure that North American
suppliers of DEF meet the standards defined by AUS-32.
The quality of DEF in the tank must be maintained.
Extreme care
should be taken to prevent any contaminants
from getting into the fluid.
NOTICE
Temperatures above 86°F (30°C) will cause DEF to
break down into ammonia.
NOTICE
Only approved DEF fluid containing the API certified
or ISO 22241 label should be used. To locate a nearby
http://www.finddef.com/def_map.php
or use the U.S. Department of Energy website at
.
