EA Approval for Multi-gas Stack Monitor

The Horiba PG250 is a highly popular portable multiparameter stack monitor which can simultaneously measure up to five separate gas components using IR detection for CO, SO₂, and CO₂; chemiluminescence for NOx; and a zirconium oxide sensor for O₂ measurements.

Over the past few months Quantitech has received many enquiries from users regarding the acceptability of PG250 results given that the analyser is usually equipped with a Zirconia cell for the measurement of Oxygen, whilst the Standard Reference Method BS EN 14789(2005) calls for the use of a paramagnetic oxygen sensor.

This issue has been addressed by the STA and the Environment Agency and the following statement by Dr Richard Gould of the EA clarifies the situation and will enable Test Laboratories to continue using the PG 250.

Dr Gould: “Our position on oxygen measurements is that it is acceptable for test laboratories to use the PG 250 within the CEN standard reference method (SRM), BS EN 14789 (2005). There are two important things to note with this CEN standard; firstly, it prescribes a technique for measuring oxygen, with associated performance standards for the technique, and secondly, it prescribes a methodology. Although the technique (Zirconia sensor) differs from the prescribed technique (paramagnetic), there is ample evidence that the Zirconia sensor meets the same prescribed performance standards specified within BS EN 14789, through the MCERTS testing and certification.

There is one caveat that test laboratories need to bear in mind; if a test laboratory wishes to use the PG 250 within BS EN 14789, the test laboratory must still use the same methodology. The only difference is that the test laboratory would be using a Zirconia sensor instead of a paramagnetic sensor as a technique.

Our position on measurements is that we prefer to apply a 'black box' approach without specifying a specific technique, unless there are practical reasons to do so. Instead, our position is to apply performance standards without specifying any particular technique.”