JJF 1562-2016Calibration Specification for Condensation Particle Counters (English PDF)

1 Scope

This specification applies to the calibration of condensation nuclei particle counters.

2 References

This specification references the following documents.

ISO 15900:2009 Measurement of aerosol particle size distribution Differential electromigration method Calibration of aerosol particle number concentration condensation nuclei particle counters for dated references, only the dated version applies to this specification; for undated references document, its latest version (including all amendments) applies to this specification.

3 Terms

4 Overview

Condensation nuclei particle counter (abbreviated as CPC in this specification) is mainly composed of saturation chamber, condensation chamber, optical detector (laser beam, prism, detection cavity, detector) and flow control system are composed of four parts. Figure 1 is a simplified structure diagram of CPC.

The working principle of CPC is. when the aerosol passes through the saturated cavity and the condensation cavity, due to the condensation of the supersaturated vapor of the working fluid on the particle surface, the particle size will increase accordingly. When it flows through the laser detection area at a certain speed, by measuring the scattered light signal of the particle per unit time, the particle number concentration in the aerosol is calculated. The working fluid in the saturation chamber is usually n-butanol, isopropanol or water.

5 Metrological characteristics

The measurement characteristics of CPC are shown in Table 1, and the performance indicators are for reference during calibration.

6 Calibration conditions

7 Calibration items and calibration methods

Calibration items can be selected according to the intended use of the instrument being calibrated. Deviations from the calibration specifications shall be noted in the calibration certificate.

8 Calibration result expression

Calibration results shall be reflected on the calibration certificate. Calibration certificates should include the following information.

a) Title. "Calibration Certificate";

b) laboratory name and address;

c) the location where the calibration is performed;

d) Identification of calibration certificate number, page number and total number of pages;

e) customer name and address;

f) The manufacturer, name, model and serial number of the instrument being calibrated;

g) Special seal for calibration of calibration units;

h) date of calibration;

i) The name and code of the technical specification on which the calibration is based;

j) The name, model, accuracy grade or uncertainty of the certified reference material used in this calibration and the main measuring equipment Degree or maximum allowable error, instrument number, certificate number and validity period;

k) Ambient temperature and relative humidity during calibration;

l) Calibration results and their measurement uncertainties;

m) a description of the deviation from the calibration specification (if any);

n) recommendations for recalibration intervals;

o) The signature and issue date of the calibrators, verifiers and approvers of the "Calibration Certificate";

p) A statement that the calibration result is only valid for the current measurement of the instrument being calibrated;

q) Statements that partial reproductions of certificates or reports are invalid without the written approval of the laboratory.

9 Recalibration interval

The recalibration interval of CPC is recommended to be 1 year. Since the length of the recalibration interval is determined by the use of the instrument, it is determined by various factors such as the user and the quality of the instrument itself. Therefore, the sending unit can independently determine the time interval for recalibration according to the actual use.

Appendix A

Condensation nuclei particle counter calibration device A.1 Composition and working principle in this specification, the calibration of the CPC counting efficiency is completed by comparing with the calibrated FCAE. calibration device it mainly includes aerosol generator, differential electromigration separator, aerosol diluter, FCAE, etc., as shown in Figure A.1.

The working principle of the calibration device is. the clean compressed air filtered by the high-efficiency filter enters the aerosol generator Finally, atomize the monodisperse polystyrene latex standard particles in the device. The generated aerosol particles pass through the particle neutralizer After reaching the Boltzmann charge balance, and then passing through the differential electromigration separator, a single component with a single charge on the surface is finally produced.

scattered aerosol particles. Through technical means such as dilution, supplementary clean air, and air extraction, the air in each channel of the aerosol splitter the particle concentration of the particle reaches a dynamic equilibrium, and flows through the FCAE and the CPC to be calibrated at a specific flow rate. will CPC's the measured value is compared with the standard value (Equation 4 in 7.4.3), thus realizing the calibration of the CPC counting efficiency.

A.2 Calibration device performance index Condensation nuclei particle counter calibration device. particle concentration calibration range (50~10000)/cm3, particle concentration the calibration uncertainty is better than 3.5% (k=2). The main performance indicators are listed in A.2.1~A.2.7 respectively.

A.2.1 Aerosol generators Using the spray principle, it can atomize polystyrene standard particles with a particle size in the range of (50~150)nm; and the concentration of aerosol particles is stable and adjustable, and the maximum concentration should not be lower than 40,000 particles/cm3, and the stability within 5 minutes is better than 1%.

A.2.2 Compressed air the maximum flow rate is at least 100L/min, and the number of particles with a particle size of not less than 0.1µm should not exceed 10/L.

A.2.3 Diffusion dryer the maximum flow rate is at least 3L/min, and the relative humidity of the dried aerosol should not be higher than 40%.

A.2.4 Differential electromigration separator in the range of (50~500)nm, aerosol particles can be selected and separated according to their electric mobility, and several any monodisperse sample with a standard deviation (GSD) less than 1.1.In the calibration certificate, p charges are carried in the aerosol (p=1,2,3) The relative standard uncertainty of the percentage of particles is better than 0.7%.

A.2.5 Aerosol diverters should have at least 2 airflow channels. In the calibration certificate, the relative standard uncertainty of the particle concentration deviation of each channel is better than 0.9%.

A.2.6 Aerosol diluters the dilution ratio is adjustable in the range of (2~100) times. In the calibration certificate, the relative standard uncertainty of the dilution ratio is better than 0.8%.

A.2.7 FCAE

It can measure the number concentration of particles in the range of (3000~8000)/cm3.In the calibration certificate, FCAE counts the relative standard uncertainty of efficiency is better than 1.0%.

Appendix B

An Example of Uncertainty Evaluation of Particle Counting Efficiency Calibration B.1 Brief description of calibration method and measurement model Calibrate the particle counting efficiency of the instrument according to 7.4 of this specification. Calculate the counting efficiency of the instrument according to formula (B.1).

B.2 Uncertainty calculation formula from the formula (B.1), it can be seen that the main factors affecting the uncertainty of measurement results are. CPC measurement results, FCAE measurement results, aerosol diverter channel deviation, aerosol diluter dilution ratio, FCAE counting effect rate, multi-charge effect correction. Uncertainty calculation formula can be derived from formula (B.1).

B.3 Evaluation and calculation of uncertainty components B.3.1 Uncertainty components introduced by CCPC in CPC measurement results According to section 7.4.2 of this specification, the measurement result of CPC is the average value of three measurement results, and the measurement results are shown in Table B.1.

B.3.2 Uncertainty introduced by aerosol diverter bias beta Calibrated by the national legal metrological verification institution, the channel deviation beta of the aerosol splitter is 0.9995 B.3.3 Uncertainty introduced by the dilution factor f Calibrated by the national legal metrological verification institution, within the range of (2~100) times dilution ratio, the relative standard of the dilution factor the quasi-uncertainty ur (f) = 0.60%.

B.3.4 Uncertainty introduced by CFCAE in FCAE measurement results According to 7.4.2 of this specification, the measurement result of FCAE is the average value of three measurement results, and the measurement results are shown in Table B.2.

B.3.5 Uncertainty introduced by FCAE counting efficiency etaFCAE Calibrated by the national legal metrological verification institution, within the range of (10~20) fA [corresponding particle concentration range is about the counting efficiency etaFCAE of (3700~7400) pieces/cm3]FCAE is 99.01%, and the relative standard introduced by calibration Uncertainty ur (etaFCAE) = 0.79%.

B.3.6 Uncertainties introduced by multiple charge effects Calibrated by the National Statutory Metrology and Verification Institute, the relative standard uncertainty introduced by the calibration of multiple charge effects B.4 Standard uncertainty in summary, the standard uncertainty of the CPC counting efficiency B.5 Expanded uncertainty the relative uncertainty of this calibration result