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1� | RTM ��� | Description of device
�.5
Functional description
The RTM 430 serves the recording of the coefficient of
absorption k [m
] of the exhaust gas for compression
-1
ignition engines (diesel engines). To this end, during
the measurement, while accelerating, a portion of the
exhaust gas from the vehicle's exhaust tailpipe is routed
via an exhaust-sample probe and a measuring chamber
sample hose (without any suction support).
The opacity is measured, which in turn is used to calcu-
late the coefficient of absorption.
�.5.1
Terminology
The effective measuring length is the light distance,
which is passed through by the smoke. It amounts to
430 mm.
The degree of opacity [%] and coefficient of absorpti-
on [m
] represent a dimension for the quantity of light,
-1
which is weakened (absorbed) by soot, white smoke
and blue smoke.
The mass concentration [mg/m
late volume in mg, which is emitted by diesel vehicles in
relation to 1 m
of exhaust gas.
3
i
Conversion of the coefficient of absorption into
mass concentration is based on the conversion table
compiled by the British Motor Industry Research
Association (MIRA).
�.5.2
Exhaust-sample probe
The exhaust sample probes are designed such that
exhaust sampling can be conducted on all the various
shapes of exhaust tailpipes. The adjuster mechanism
enables a minimum immersion depth into the exhaust
pipe of 5 cm to be assured.
Furthermore, the design also ensures that a minimum di-
stance of 10 mm to the inner exhaust-pipe wall is given.
�.5.�
Measuring chamber
In order to measure the opacity an optical sender (LED)
emits green light, which is partly absorbed by the ex-
haust gas in the measuring chamber.
The non-absorbed portion of light arrives at the recei-
ver (photodiode) and converts the optical signals into
electronic data.
Soot deposits at the optical windows are avoided by
means of air curtains (blow-by purge air).
In order to avoid having any condensation on the walls
of the measuring chamber and to keep the exhaust-gas
temperature above the dew point, the measuring cham-
ber is equipped with a heater.
The null compensation runs automatically.
|
1 689 979 651
2009-04-06
] indicates the particu-
�
�.5.�
Correct operation
In order to guarantee correct operation, the exhaust-gas
temperature and the measuring chamber temperature
are constantly monitored.
In addition to this, prior to each measuring cycle a null
compensation process is performed, whereby the con-
tamination level of the optical measurement path is also
checked.
Measurement can no longer take place if one of the sta-
ted parameters is outside the permissible tolerance.
�.6
Special accessories
Designation
RTM base
Car exhaust-sample probe
(Probe length: 2 m, Internal diameter of
probe: 10 mm; Suitable for exhaust diame-
ter < 70 mm; only ...413, for measurements
in combination with a dynamometer)
Truck exhaust-sample probe (Internal
diameter of probe: 16 mm; Suitable for
exhaust diameter < 70 mm)
Exhaust-sample hose
Ø 16 mm, length 1 m
Ø 16 mm, length 3.5 m
Hose for exhaust-gas recirculation in
extraction system
RTM 430 connecting cable (12 m)
Heated exhaust-sample hose (5 m)
Clamping fixture with telescopic rod
Order number
1 685 200 082
1 680 790 046
1 680 790 041
1 680 712 195
1 680 712 201
1 680 707 100
1 684 465 391
1 684 510 045
1 688 040 258
Robert Bosch GmbH
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