INTERLABORATORY TESTS OF EMISSION MEASUREMENTS IN FRANCE USING A TESTING BENCH

ABSTRACT

It is well known that interlaboratory tests are a powerful tool to improve the quality of measurements. However they are difficult and costly to organise in the framework of emission measurements because of several reasons (too small measuring platforms, access to industrial plants…).

In order to facilitate these tests, French authorities asked INERIS to built a testing bench, which could simulate industrial gaseous emissions of easily modified composition. The bench was originally designed mainly for having a constant concentration of gaseous pollutants (SO₂, NO_x, HCl, VOC). Work is in progress for semi-volatile pollutants injection.

The bench is designed and equipped in such a way that five teams may work in parallel, which allows having statistical comparison. For the time being, it is mainly used for:

• - validation of measurement methods before their standardisation
• - proficiency testing for laboratories in view of their accreditation/approval

A description of the bench and examples of results will be given.
 

1 INTRODUCTION

To be accredited, the laboratories which are involved in emission measurements have to provide the uncertainty attached to their measuring values. They can find some information in the most recent CEN standard, but they still do not know if they are implementing the standardised procedure properly unless they participate to interlaboratory campaigns.

Thus, interlaboratory tests are a powerful tool to improve the quality of measurements.

These campaigns are not so easy to organise on a plant and are expensive. Only very few teams can be simultaneously involved and the range of concentrations covered by one plant is quite often very narrow.

Therefore, in order to make these tests easier and more frequent, French authorities asked INERIS to design and build a testing bench, which could simulate varied industrial gaseous effluents.

The bench, which is a horizontal loop, was originally designed mainly for measuring concentrations of gaseous pollutants  (SO₂, NO_x, HCl, VOC) but some studies are in progress for semi-volatile pollutants injection.

Up to now, six interlaboratory campaigns with French bodies and one with European laboratories have been organised, measuring O₂, CO, SO₂, NO_x, H₂O. Some interlaboratory campaigns are also under way for mercury and for PAH generated by a wood stove.

The bench is designed and equipped in such a way that five teams may work in parallel, which allows having statistical comparisons.

For the time being, it is mainly used for:

• · validation of measurement methods before their standardisation
• · proficiency testing for laboratories in view of their accreditation/approval

This presentation gives the main results and statistical evaluation of six campaigns for the determination of O₂, SO₂, NO_x, CO, TOC and H₂O.