7 - MAINTENANCE
Removal of NO
x
requires a chemical reaction. This chem-
ical reaction takes place in the SCR
(13)
.
DEF/A
D
B
LUE
®
reacts with the SCR catalyst to convert NO
x
to harmless
nitrogen and water vapor.
To assure that the emission system is functioning cor-
rectly, a downstream NO
x
sensor
(16)
is located in the
exhaust stream at the outlet of the SCR.
The NH
3
sensor
(15)
, located at the outlet of the SCR cat-
alyst monitors ammonia (NH
3
) levels to ensure the proper
amount of
DEF/A
D
B
LUE
®
is being used.
Temperature is very important to the chemical reactions
that take place in the emission control system. An SCR
upstream temperature sensor
(12)
is located in the ex-
haust stream at the inlet of the SCR and compares the
reading of the SCR downstream temperature sensor
(14)
located in the exhaust stream at the outlet of the SCR. The
catalyst requires about
230 °C
(
446 °F
) for the chemical
reaction to take place.
7-28
Summary of Contents for 621G Stage IV
Page 42: ...2 SAFETY INFORMATION Empty tool LEEN11T0024AA 20 2 22 ...
Page 60: ...2 SAFETY INFORMATION 2 40 ...
Page 137: ...3 CONTROLS AND INSTRUMENTS Inducement and validation re starts LEIL14WHL0394HA 2 3 77 ...
Page 138: ...3 CONTROLS AND INSTRUMENTS Validation re start procedure LEIL15WHL0608HA 3 3 78 ...
Page 150: ...3 CONTROLS AND INSTRUMENTS 3 90 ...
Page 166: ...4 OPERATING INSTRUCTIONS RCPH10WHL045BAH 7 4 16 ...
Page 168: ...4 OPERATING INSTRUCTIONS RCPH10WHL045BAH 9 4 18 ...
Page 170: ...4 OPERATING INSTRUCTIONS RCPH10WHL045BAH 12 4 20 ...
Page 208: ...6 WORKING OPERATIONS 6 18 ...
Page 229: ...7 MAINTENANCE DEF AdBlue technical faults LEIL14WHL0392HA 4 7 21 ...
Page 370: ...7 MAINTENANCE 7 162 ...