en
18 | BEA 055 | Product description
3.4
Description of unit
The BEA 055 consists of a computer board with tem-
perature, engine speed and exhaust gas measurement
functions. In the BEA 950, the communication between
the PC and the BEA 055 is carried out via a USB con-
nection.
14
13
11-16V
12
10
11
Fig. 1:
BEA 055
1 Coarse filter GF2
2 Coarse filter GF3
3 Exhaust gas measurement inlet
4 Active carbon filter AF1
5 O
sensor
2
6 Exhaust gas measurement outlet
7 Condensate port
8 Calibrating gas inlet
9 NO sensor (special accessory)
10 Power supply socket
11 USB connection
12 Connection for connecting cable 1 684 463 810
BDM 300
1)
13 Connection for oil temperature sensor
14 LED
sometimes included in special accessories
1)
3.5
LED status
LED
Off
Alternate orange and green flashing
at one-second intervals
Rapid alternate orange and green
flashing
Rapid alternate orange and green
flashing (Bosch Emissions Analysis
software not started)
Red light
3.6
Description of function
The BEA 055 is used to measure the exhaust gas com-
ponents CO, HC, CO
, O
2
2
ted). The excess air factor (Lambda) is calculated on
the basis of the gas values measured.
The non-dispersive infrared method (NDIR – non-disper-
sive infrared spectroscopy) is employed for measuring
the CO, CO
and HC quantities. The oxygen is deter-
2
mined using a sensor with electro-chemical action.
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2016-12-14
459906_1Ko.eps
GF 3
GF 2
O2
AF I
N0
9
8
7
6
5
4
3
to BEA 040/
1)
Status
BEA 055 off
BEA 055 on and ready
for operation
USB communication
with Bosch Emissions
Analysis software
Defective firmware
BEA 055 defective
and NO (NO can be retrofit-
Warm-up time
The BEA 055 warm-up time is approx. 1 minute. Mea-
surements cannot be taken during this period.
Zero calibration at the start of exhaust emissions
tests
After switching on the pump, the zero point of the
analysis system is automatically calibrated (duration
30 seconds) with ambient air (zero gas).
1
Zero calibration during exhaust emissions tests
2
Following the start of an exhaust emissions test, the
BEA 055 automatically implements a system check with
ambient air at irregular intervals. To perform the system
check, the BEA 055 switches a solenoid valve to ambi-
ent air. The system is flushed with zero gas for 30 sec-
onds. An active carbon filter removes the hydrocarbons
from the ambient air drawn in.
Lambda air ratio measurement
The BEA 055 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
Brettschneider formula:
[
]
CO
H
[
]
[ ]
CO
+
+
O
+
2
2
2
λ
=
H
O
CV
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) *
*
Dependent on the fuel used.
Oxygen measurement
The BEA 055 is equipped with an O
sor is a wearing part.
The oxygen measurement is automatically adjusted to
the air oxygen content of 20.9 % by vol and is required
for Lambda calculation.
and oxygen concentra-
2
[
]
O
3 5
,
CV
(
[
CV
x
−
x
CO
[
]
4
CO
2
3 5
,
+
CO
2
(
)
CV
[
] [
]
[ ]
x
CO
+
CO
+
K x HC
2
1
sensor. The O
2
Robert Bosch GmbH
)
] [
]
+
CO
2
sen-
2