Particle number concentration standards at NMIJ, including a new calibration service with an inkjet aerosol generator.

Transcription

1 Particle number concentration standards at NMIJ, including a new calibration service with an inkjet aerosol generator Hiromu Sakurai hiromu.sakurai@aist.go.jp Particle Measurement Research Group National Metrology Institute of Japan (NMIJ) National Institute of Advanced Industrial Science and Technology (AIST) April 15, 2015 Presented at the Particulate Workshop of CCQM GAWG

2 NMIJ s Particle Measurement Research Group Molecular weight CRMs Particle size and size distribution CRMs Calibration services Particle size Particle number concentration Liquid-borne particles Airborne particles Reference materials Particle size Specific surface area Molecular weight of polymers Photo by JSR Co. Electro-gravitational aerosol balance method for particle mass measurement Specific surface area RMs Faraday-cup aerosol electrometer for aerosol particle number concentration 9 researchers + 5 technical staff members 2

3 Calibration service by NMIJ for airborne particle number concentration with Faraday-cup aerosol electrometer 3 Calibration service started in 2008 Direct comparison with the reference FCAE Concentration from 1 x 10 3 cm -3 to 1 x 10 4 cm -3 Participated in EURAMET 1244 and 1282 NMIJ s Faraday cup Calibration service expanded in 2013 New method to extend the concentration range to less than 10 3 cm -3 using diluters was developed. Calibration down to 1 cm -3 is available. NMIJ s calibration system

4 New calibration service by NMIJ for particle number concentration Inkjet Aerosol Generator (IAG) by Dr. Kenjiro Iida Monodisperse droplets [solute+solvent] Monodisperse aerosol particles [solute] 300 mm Clean air Inkjet Solvent evaporation 740 mm Gravity Particle generation rate is controlled by the frequency of voltage-pulses applied to a piezoelectric elements inside the inkjet head. Particle diameter is controlled by the concentration of solute in a droplet.

5 by Dr. Kenjiro Iida Range of Calibration Service 5 Calibration setup depends on the flowrate of the OPC to be calibrated. Range of calibration service Particle count rate : 10 s s -1 Particle number concentration: 0.02 cm cm 30 L/min 2 cm cm 0.3 L/min Particle diameter:0.5 µm - 10 µm Sheath flow chamber 0.3~0.5 L/min 0.5~30 L/min

6 by Dr. Kenjiro Iida Traceability to SI-Units 6 Particle generation rate Volumetric flowrate

7 by Dr. Kenjiro Iida Industrial applications of the OPC 7 Particle diameter range > 0.1 µm > 0.3 µm > 5-10 µm Monitoring super-clean room Evaluation of filter units Applications Monitoring cleanrooms for manufacturing: pharmaceutical products, foodstuff, cosmetic products, semiconductor devices, liquid crystal panels. Monitoring environment for painting automobiles, assembling optical components, making steel-products. Most application cares about airborne particles whose diameters are above 0.3 µm. Regulations for making pharmaceutical products (i.e., Good Manufacturing Practice) requires the measurements of number concentration of particles whose diameters are above 0.5 µm and 5 µm. OPC s market is expected to grow (at least in Japan.) ISO 21501& JIS B 9921 requires the detection efficiencies of OPCs to be calibrated.

8 NMIJ s inkjet aerosol generator The ratios of the counted rate to the generation rate, when compared with an optical particle counter (RION KC- 01D; D p50 = 0.3 µm), show very good agreement in the size range where the counting efficiency of the counter is expected to be unity.

9 9 Detection efficiency based on particle count rate by Dr. Kenjiro Iida η count Particle count rate of an OPC N L = t η count = L L Particle number reported by the OPC Sampling time Detection efficiency based on particle count rate L = η IAG F Particle generation rate of the IAG Frequency of voltage-pulses applied to the inkjet head. Particle generation efficiency Efficiency for producing one droplet from one voltage pulse applied to the inkjet head. η IAG We assume = 1

10 Uncertainty budget for by Dr. Kenjiro Iida ηcount 10 Symbol Source of variation Type D.O.F Relative standard uncertainty Day-to-day reproducibility A ( ) u η IAG Repeatability A Bias caused by particle losses and false counts. B Coincidence correction B uf ( ) ul ( ) u ( η ) r count Calibration certificate of frequency counter B Reproducibility and repeatability A Repeatability(n=20) A Relative standard uncertainty Relative expanded uncertainty ( k = 2)

11 11 Comparing calibration results for CPCs between FCAE and IAG The range of calibration service by Dr. Kenjiro Iida Particle number concentration (cm -3 ) FCAE Test A Test B IAG Particle diameter (µm) Test A: Neglect the size-dependence of detection efficiencies between nm particle diameter range (Yli-Ojanpera et al, 2012) then compare the calibration results under the same particle number concentration. Test B: Apply an empirical correction factor for the concentration dependence of the detection efficiency then compare the calibration results under the same particle diameter.

12 12 by Dr. Kenjiro Iida Comparing the detection efficiencies based on particle number concentration, η conc. Test A Test B CPC Flowrate 1 L/min (TSI-3772) 0.3 L/min (TSI-3775) η conc. Error bars are U(k=2). The calibration results of the IAG falls within U(k=2) of the FCAE-based results. Calibration service with the IAG begins in For more information about the IAG contact Dr. Kenjiro Iida (kenjiro.iida@aist.go.jp)

13 Method for testing particle size spectrometers using monodisperse particles for checking overall system performance on particle number concentration by Ms. Yoshiko Murashima Monodisperse particles Reference CPC Spectrometer under test Well-defined laboratory-generated particles such as DMA-classified polystyrene latex particles i.e., known size, charging state, composition, morphology,... Reproducible by manufactures, users, and testing labs Size distribution density function Spectrometer under test Particle size dcc NN dlogdd dlogdd Density function by particle size spectrometer under test Number concentration Reference CPC Time CC NN Concentration by reference CPC 13