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22 | BEA ��� | Product description
Excess air factor measurement
The BEA 060 calculates the excess air factor (Lambda)
from the measured HC, CO, CO
tions.
Precise oxygen measurement is important for Lambda
calculation. Lambda calculation and oxygen measure-
ment must be activated for this purpose.
The Lambda value is calculated with the aid of the Bret-
tschneider formula:
[
]
CO
H
[
]
[ ]
CV
CO
+
+
O
+
x
2
2
4
2
λ
=
H
O
CV
CV
+
−
x
1
4
2
[]
Concentration in % by vol, also for HC
K
Conversion factor for HC from NDIR to FID (value 8)
1
Hcv
Hydrogen/carbon ratio in the fuel
(typically 1.7261) *
Ocv
Oxygen/carbon ratio in the fuel
(typically 0.0175) *
* Depending on the fuel used.
Oxygen measurement
The BEA 060 is equipped with an O
sor is a wearing part.
The oxygen measurement is automatically compared to
the air oxygen content of 20.9 % by vol and is required
for Lambda calculation.
|
1 689 989 112
2012-11-26
All manuals and user guides at all-guides.com
and oxygen concentra-
2
[
]
O
3 5
,
CV
(
[
] [
−
x
CO
+
CO
2
[
]
CO
2
3 5
,
+
CO
2
(
)
[
] [
]
[ ]
CO
+
CO
+
K x HC
2
1
sensor. The O
2
2
�.8
Exhaust measurements for 2 cycle
engines
Vehicles with two cycle engines have higher HC emis-
sions and also deposit oil compared to vehicles with four
cycle engines. Oil mainly consists of hydrocarbons (HC).
This forms deposits on the walls of the gas path (ex-
haust extraction probe, exhaust extraction hose, filter) if
no precautions are taken.
These deposits result in an HC concentration display
(residual value display), even if no exhaust measure-
ment was performed, thus the actual value of this
)
]
residual value is adulterated (increased) during an HC
measurement.
This affect, known as "hang up" by experts, appears in
all exhaust instruments, and is not related to the prod-
uct. It is only visible in instruments that measure HC.
These deposits can mostly be prevented by inserting
activated carbon filters. These filters bind and neutral-
ize the greatest part of oil and volatile hydrocarbons.
This type of filter has a limited service life.
!
sen-
Always use an activated carbon filter when measur-
ing exhaust in 2 cycle engines. This activated carbon
filter must be inserted behind the rough filter in the
gas path.
i
We recommend always using a separate, second
outer gas path (exhaust extraction probe, exhaust
extraction hose, GF1 filter and activated carbon
filter) when measuring exhaust in 2 cycle engines.
All necessary parts required for this are contained in
the 2 cycle set 1 687 001 283.
Robert Bosch GmbH
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