JJF 1800-2020 English PDF (JJF1800-2020)

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JJF 1800-2020: Calibration specification of aerosol photometers
JJF 1800-2020
JJF
METROLOGY SPECIFICATION OF THE
PEOPLE’S REPUBLIC OF CHINA
Calibration Specification for Aerosol Photometers
ISSUED ON: JANUARY 17, 2020
IMPLEMENTED ON: APRIL 17, 2020
Issued by: State Administration for Market Regulation
Calibration Specification for Aerosol Photometers
1 Scope
This Specification applies to the calibration of light scattering principle aerosol
photometers with a measurement range of (0.01~100) μg/L. The aerosol photometers
with other measuring ranges can be calibrated with reference to this Specification.
2 Terms
PAO-4 aerosol
Aerosol refers to a colloidal dispersion system formed by solid or liquid small particles
dispersed and suspended in a gas medium. It is also called as gas dispersion system. Its
dispersion phase is solid, liquid or solid-liquid mixture. PAO-4 aerosol in this
Specification refers to polydisperse aerosol, which takes poly-alpha-olefin oil (PAO)
with a kinematic viscosity of 4m2/s as the generating medium and is generated by the
fog mixing device of the aerosol photometer.
3 Overview
Aerosol photometer (hereinafter referred to as the instrument) is an instrument used to
measure the leakage rate of high-efficiency filters and the leakage rate of high-
efficiency filtration systems installed with high-efficiency filters. Its working principle
is that: the instrument draws air samples from the upstream and downstream ends of
the high-efficiency filter or high-efficiency filter system under test at a constant flow
rate. The sampling unit delivers the air sample to the measuring unit. The measurement
unit uses forward scatter measurements to measure the mass concentration of aerosols
in air samples. The data processing unit analyzes the measurement results and calculates
the ratio of the two, so as to obtain the leak rate of the system under test. Finally, the
measurement results are outputted by the display unit. The schematic diagram of the
instrument structure is shown in Figure 1.
5.2 Metrology standard instruments
5.2.1 Precision aerosol photometer: the maximum allowable error of mass
concentration does not exceed ±10%;
5.2.2 Flow standard device: the measurement range is (0~50)L/min; the maximum
allowable error does not exceed ±1.0%.
5.2.3 Aerosol fog mixing device: a device that can generate PAO-4 aerosol with
controllable concentration and uniform mixing. When a low concentration
(0.01~1)μg/L aerosol occurs, its concentration stability does not exceed 10%/4h. When
a high concentration (10~100)μg/L aerosol occurs, its concentration stability does not
exceed 5%/20min.
6 Calibration items and calibration methods
6.1 Preparation before calibration
Connect the calibrated instrument, precision aerosol photometer and aerosol fog mixing
device as required. According to the use requirements of each equipment, the normal
operation of preheating shall not be less than 10min.
6.2 Calibration items
6.2.1 Sampling flow indication error
Enable the downstream sampling mode of the instrument under test. After it is stable,
connect the flow standard device to the downstream sampling port of the instrument
through the sampling tube (see Figure 2). Read the standard flow value and the flow
indication value of the calibrated instrument, respectively. Calculate the sampling flow
indication error according to formula (1). Repeat the above measurement process 3
times. Take the average value of the indication error obtained by 3 measurements as the
measurement result.
Where,
ΔQ - The flow indication error, L/min;
Qm - The indication of flow rate of the calibrated instrument, L/min;
Qs - The standard flow value, L/min.
b) Laboratory name and address;
c) Location where the calibration is performed (if not performed in the laboratory);
d) Unique identification (such as number) of the certificate or report, identification
of each page and the total number of pages;
e) Name and address of the calibration submitter;
f) Description and clear identification of the subject being calibrated;
g) Calibration date. If relevant to the validity and application of the calibration
results, the date of acceptance of the subject to be calibrated shall be stated;
h) Sampling procedures shall be described if relevant to the validity and application
of calibration results;
i) Identification of the technical specification on which the calibration is based,
including name and code;
j) Traceability and validity of the measurement standards used in this calibration;
k) Description of the calibration environment;
l) Description of calibration results and measurement uncertainty;
m) Signature, title or equivalent identification of the issuer of the calibration
certificate or calibration report, and the date of issue;
n) Statement that the calibration result is valid only for the subject being calibrated;
o) Statement of the certificate or report may not be partially reproduced without the
written approval of the laboratory.
8 Recalibration time interval
The recalibration time interval of the instrument shall be determined by the user
according to the usage of the instrument, the performance of the instrument itself, and
so on. It is recommended that the recalibration time interval shall not exceed 1 year.
During the two adjacent calibration periods, if there is doubt about the test data of the
instrument or the instrument is replaced with main parts and repaired, the instrument
shall be recalibrated.
Annex A
Calibration method for concentration indication error of precision aerosol
photometer
A.1 Calibration conditions
A.1.1 Environmental conditions
Temperature: (15~30)℃. Relative humidity: not more than 85%. Supply voltage: AC
(220±22)V, (50±1)Hz.
A.1.2 Filter membrane
Round. The diameter is (37±0.25)mm. The pore size is not more than 2μm. The
thickness is (0.2~0.25)μm. At a clean air flow rate of 0.45m/s, the pressure drop shall
be less than 3kPa. The mass increase value after exposure to 35% RH air for 24h does
not exceed 10μg. Inorganic filter membranes such as glass fiber filter membrane and
quartz filter membrane can be selected. The retention efficiency of the filter membrane
for 0.3μm standard particles is not less than 99.99%.
A.1.3 Calibration system of precision aerosol photometer
a) Sampling device: The flow range is (0~50)L/min. The stability of 4h is not higher
than 5%.
b) Flow standard device: The range is (0~50) L/min. The maximum allowable error
does not exceed ±1.0%. The cumulative sampling volume can be displayed.
c) Balance: Accuracy level is . The actual division value is not more than 1 × 10-
6g.
d) Aerosol fog mixing device: A device that can generate PAO-4 aerosol with
controllable concentration and uniform mixing. Use a precision aerosol photometer
to measure the fog concentration of the device. At the low concentration of
(0.01~1)μg/L, its concentration stability is not more than 10%/4h. At the high
concentration of (10~105)μg/L, its concentration stability is not more than
5%/20min.
A.2 Calibration method
A.2.1 Preparation before calibration
A.2.1.1 Appearance inspection of filter membrane: It shall be ensured that the edge is
flat. The thickness is uniform. There is no burr. There is no pollution. There must be no
pinholes or any damage.
Annex B
Examples for measurement uncertainty evaluation of mass concentration
indication error of precision aerosol photometer
B.1 Overview
The precision aerosol photometer...