Ensuring Instrument Performance for Ambient Particle Monitoring

EN 16976 and CEN/TS 17434 pertain to the measurement of ultrafine particles (UFP) in the atmosphere. Their goal is to harmonize (i.e. make consistent) the measurement techniques used for measuring the particle number concentration (EN 16976) and particle size distribution (CEN/TS 17434:2020). Such ‘harmonization’ ensures that data from various sites can more easily be compared. Instrument performance issues, of course, erode data quality, and undermine the extent to which data can be compared. How can the accurate performance of these continuous-use instruments be confirmed?

The authors of the CEN specifications understand the importance of periodically validating, and occasionally calibrating, the Condensation Particle Counters (CPCs) and Mobility Particle Size Spectrometer (MPSS, i.e. SMPS™) systems used in CEN-compliant ambient air monitoring efforts.

 

Validation: Periodic Performance Check

The EN 16976 and CEN/TS 17434:2020 specifications require that certain performance confirmation (i.e. ‘validation’) steps be taken at designated frequencies. TSI can support you in your efforts to validate your CEN-related instrumentation. These validation actions, their designated frequency, and the TSI instrumentation relevant to each step are as follows:

Component	Action	Section CEN/TS 16976	Section CEN/TS 17434	Frequency	Recommended TSI® Tools
Sampling System	Confirm inlet flow	7.6	8.6	Monthly	Flow Calibrator 4148
	Leak check of dries	9.2.13	10.2.12		Condensation Particle Counter 3750-CEN
Condensation Particle Counter (CPC)	Inlet flow check	9.2.7	10.3.3		Flow Calibrator 4148
	Zero (background) check	9.2.5	10.3.7		Particle Zero Check Filter
Scanning Mobility Particle Sizer™ (SMPS™)	Inlet flow check	n/a	10.3.2		Flow Calibrator 4148
	Zero (background) check		7.2.5		Particle Zero Check Filter
	Leak check		10.3.8		Flow Calibrator 4148 and Particle Zero Check Filter
	Particle size accuracy check		7.2.3	Quarterly	Monodisperse Aerosol Generator 3940A
	Delay time check		10.3.6		Monitoring license for Aerosol Instrument Manager® 11 software for SMPS™

 

Calibration: More Thorough; any Problems are Rectified

Annual calibration is required by both CEN standards; this necessitates sending the instruments in question to a calibration center such as are overseen by the European Center for Aerosol Calibration (ECAC).

During a formal calibration, the performance of the instrument is examined in greater detail than can be done in the field. In some cases, if an adjustment to the instrument is found to be necessary, the calibration center may be able to perform the adjustment. After all tests are passed, the result is an instrument that produces accurate data, and is thus ready for re-deployment for continuous monitoring in compliance with the CEN specification(s).

 

Contact TSI for guidance regarding either establishing a new CEN-compliant ultrafine particle monitoring solution, or ensuring that your operating procedure for your TSI CEN-SMPS™ is compliant with CEN requirements.