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2.
General information
2.1
Explanation of symbols used
The following pictographs are used in these Operating Instruc-
tions:
i
Info
!
Attention
2.2
Application
The ETT 8.71 Exhaust-gas Analyser is used for measuring the
concentration of car exhaust emissions, either for monitoring or
engine diagnostic purposes. The unit can be used on vehicles fitted
with a 4-stroke spark-ignition and 4-stroke rotary-piston (Wankel)
engine. Measurements can only be performed on 2-stroke engines
if the appropriate special accessories are used.
(see Section 3.6).
The instrument can only be operated together with a test system
(e.g. MOT 151, 250, FSA and Emission System Analysis) and it
is to this end equipped with appropriate interfaces.
If the unit is to be used for applications which require calibration,
the relevant regulations for the area/country in which it is operated
must be observed.
2.3
User groups
The ETT 8.71 has been designed for use by trained expert person-
nel in the automotive industry. Read these Operating Instructions
carefully for your own safety and to prevent the unit from being
damaged through improper usage.
22
3.
Description of the unit
3.1
Functional description
The ETT 8.71 is used for measuring the exhaust-gas components
CO, HC, CO
,O
and NO. The lambda air ratio is calculated on
2
2
the basis of the emissions values measured.
The following measurement ranges are covered:
CO
Carbon monoxide
HC
Hydrocarbons
(using hexane as a basis)
CO
Carbon dioxide
2
O
Oxygen
2
λ
Lambda air ratio
CO
vrai
NO
Nitric oxide
The non-dispersive, infrared process is used for measuring the
CO, CO
and HC components (NDIR - non-dispersive infrared
2
spectroscopy).
The oxygen content is measured using an electrochemically acting
sensor.
The values measured are transferred via the serial interface to the
test system which then either displays or prints them out.
The Lambda value is calculated according to the Brettschneider
formula.
[ ]
Concentration in % vol., for hydrocarbons also (HC)
K
Conversion factor for HC from NDIR to FID (value 8)
1
H
Hydrogen-carbon ratio in fuel (typical 1.7261) *
CV
O
Oxygen-carbon ratio in fuel (typical 0.0175) *
CV
*
Depends on the fuel used. These values can be changed
by the after-sales service from Bosch.
0 ... 10.00 % volume
0 ... 9999 ppm
0 ... 18 % volume
0 ... 21 % volume
0.500 ... 1.800
0 ... 10 %
0–5000 ppm
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