Pegasor announces sensor calibrations for particle mass and number
9 May 2012
Pegasor announced that it has successfully completed extensive calibration of its soot sensor for mass-based particle measurements. Two calibrations were developed: (1) for the simultaneous measurement of particle mass and number and (2) for accurate particle mass measurement. The calibration was developed in cooperation with industrial and academic partners.
Pegasor PPS-M sensor has been developed for monitoring of ultrafine particle concentrations in a wide variety of applications. The Pegasor sensor is based on a particle charging technique known as “escaping current”. Contrary to most soot sensors developed for coming diesel OBD requirements, the Pegasor sensor does not collect particulates and provides a real time measurement.
With the newly developed calibrations, the sensor can be used for the detection of particulate mass and numbers. When set to detect the 23 nm lower cutoff diameter particles, the sensor is good for measuring the total number of particles and gives very good correlation to PMP systems, according to Pegasor, with a "reasonable accuracy" for a simultaneous total mass measurement.
In the mass-only calibration, optimized sensor voltages are applied to remove part of the ultrafine particles. In this measurement mode, the PPS-M mass reading becomes insensitive to particle size distribution in all automotive applications—including GDI, diesel, and downstream DPF—said Pegasor. In other words, the new calibration allows to operate the sensor so that the particle size distribution has practically no influence on the results. If the new calibrations are indeed robust, this would represent a significant achievement, as the problem of varying size distribution presents a major challenge in the development of real time particle mass instruments. Pegasor has filed a patent application (not yet published) for this data reduction technology.
Two Count Median Diameter (CMD) settings corresponding to the new calibrations—"number and mass" and "mass only"—will be available in the coming version 2.0 of the Pegasor PPS Plotter software.