Project: Assessment of Semtech On-Board Emissions Measurement Equipment

Reference: S0229/VB

Last update: 22/01/2004 15:55:05


The objectives of this project are to:
* Compare emissions measurements using the Semtech system with those made using laboratory Constant Volume Sampling (CVS) measurement system when running a heavy duty vehicle on a chassis-dynamometer;
* provide an initial evaluation of the repeatability of emissions measured on a test track drive cycle; and
* provide an initial assessment of the correlation of on-track emissions measurements using the Semtech with those measured on the chassis dynamometer using a CVS system.


This project is being undertaken at relatively short notice to ascertain the feasibility of using new State-of-the-art on-board measuring equipment to measure emissions when driving over a drive cycle on a test track or when running on-road. This will involve comparing the emissions measurements recorded by the Semtech equipment on a Chassis-dynamometer, with those of laboratory equipment under the same conditions. The Semtech equipment will then record emissions from the same vehicle driving the same test cycle on a test track, and these measurements will be compared to the Chassis-dynamometer results. If successful, the small cost of this project could be recouped many times over when conducting future emissions measurement work. Another potential benefit of this type of equipment is the ability to measure emissions from vehicles that are too large for currently available chassis-dynamometers.


Millbrook Proving Ground Ltd
Millbrook, Bedford, MK45 2JQ
+44 (0)1525 408408

Contract details

Cost to the Department: £26,410.00

Actual start date: 03 February 2003

Actual completion date: 22 December 2003


MBK 03/0592. Development of On Track Chassis Dynamometer Drive Cycles and Subsequent Evaluation of Sensors Europe On Board Emissions Sampling System
Author: Millbrook Proving Ground Ltd
Publication date: 06/01/2004
Source: Contact:
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Summary of results

  1. Results showed the correlation between the CVS concentration measurements and Sensors Inc concentration measurements to be very good. Total exhaust mass flow measurements correlated well at low speeds but were consistently too high using the Sensors Inc system under high speed driving. The equipment manufacturer agreed that further development work was required on the probe and that the inconsistency was unlikely to be solely due to the contractor accidentally disturbing the sensors. Calibration and installation requirements suggest that the equipment will not be suitable for use on vehicles in-service. However, on track use is perfectly feasible and the ability to replicate a dyno drive cycle on track has been demonstrated. Errors by the contractor during the project make mass flow results and results from the on-track bus testing of limited value. Otherwise the results are credible.