GB/T 15432-1995 Gravimetric method for determination of total suspended particulate matter in ambient air
Some standard content:
National Standard of the People's Republic of China
Ambient air
Determination of total suspended particulates
Ambient air-Determination of total suspended particulates-Gravimetric method1 Subject content and scope of application
1.1 Subject content
This standard specifies the gravimetric method for determining total suspended particulates. 1.2 Scope of application
GB/T154321995
This standard is suitable for the determination of total suspended particulates in the air using a large flow plate or medium flow plate total suspended particulate sampler (referred to as a sampler), and the detection limit of the method is 0.001mg/m3. This method is not applicable when the total suspended particulate content is too high or the filter membrane resistance is greater than 10kPa when sampling in foggy weather.
2 Principle
A fixed volume of air is extracted at a high speed through a sampler with a fixed cutting characteristic. Suspended particles in the air with a particle size less than 100 μm are retained on the filter membrane with a constant weight. The concentration of total suspended particles is calculated based on the difference between the filter membrane weights before and after sampling and the sample volume. After the filter membrane is treated, component analysis is performed. 3 Instruments and Materials
3.1 Large or medium flow sampler: It should be in accordance with the provisions of HYQ1.1-89. Technical Requirements for Total Suspended Particle Samplers (Interim)>. 3.2 Orifice flowmeter:
3.2.1 Large flow orifice flowmeter: Range 0.7~1.4 m/min; flow resolution 0.01 m/min, accuracy better than +2%. 3.2.2 Medium flow orifice flowmeter: basic range 70~160L/min: flow resolution 1L/min; accuracy better than ±2%: 3.3 Dagger-shaped tube differential pressure gauge: minimum scale 0.1 hPa, 3.4 X-ray film viewer, used to check whether the filter membrane has defects. 3.5 Numbering machine: used to number the filter membrane and the filter membrane. 3.6 Insert: used to clamp the filter membrane.
3.7 Filter membrane: ultra-fine glass fiber filter membrane, the dispersion efficiency of 0.3pm standard particles is not less than 99%, when the air flow velocity is 0.45m/s, the resistance of a single filter membrane is not more than 3.5kPn, at the same air flow velocity, the weight loss of 5h.1cm2 of air purified by the high-efficiency filter is not more than 0.012 mg.
3.8 Filter membrane bag: used to store the dust collection filter membrane folded in half after sampling. The bag surface is printed with numbers, sampling date, sampling location, sampling person and other columns. 3.9 Filter membrane storage box: used to store and transport filter membranes, to ensure that the filter membranes are flat and not folded before the sample is received. 3.10 Constant temperature and humidity chamber: The air temperature in the chamber is required to be continuously adjustable within the range of 15-30℃, with a temperature control accuracy of ±1℃; the relative humidity of the air in the chamber should be controlled at (50+5)%. The constant temperature and humidity chamber can work continuously. 3.11 Too half,
National Environmental Protection Agency approved on March 25, 1995, 19950801 implementation
GB/T 15432--1995
3.11.1 Total suspended particulate matter balance: used for weighing large flow sampling filter membranes. Weighing range 10g sensitivity 1mg reproducibility (standard deviation) 2mg
3.11.2 Analytical balance, used for weighing mid-flow sampling filter membranes. Weighing range ≥10g Sensitivity 0.1mg; Reproducibility (standard deviation) ≤0.2mg.
4 Flow calibration of sampler
4.1 Before the newly purchased or repaired sampler is put into use, flow calibration is required; the sampler in normal use needs to be calibrated once a month.
4.2 Flow calibration steps:
4.2.1 Calculate the flow rate at the working point of the sampler: The sampler should work at the specified gas flow rate, which is called the working point of the sampler. Before formal sampling, the sampler needs to be adjusted to work at the correct working point, and the following steps are followed. The air extraction speed W of the sampling port of the sampler is 0.3I/s. The working point flow rate Qn (m/min) of the large flow sampler is Qr = 1. 05
The working point flow rate r (1./min) of the medium flow sampler is Q - 60 000W XA
Where: A is the cross-sectional area of the sampling port of the sampler, m. Convert the calculated value of Q or Qm into the flow hood QHn (m/min) or Qm (L/min) under standard conditions QH - (QHPT/(TPN)
QMK = (QmPT:)/(TP)
In the play: T
Monthly average temperature of the test site, K;
Py——standard pressure, 101.3kPa,
T·standard temperature.273K;
P—average atmospheric pressure at the test site, kPa; altitude of the test site, m.
log101.3 — h/18 400
Substitute QN or QM~ into the formula () Q, calculate the correction term Y, and then calculate AH (Pa) according to formula (7) Y -- BQ - A
In the formula, the slope B and intercept A are given by the calibration department of the orifice flow meter, AH -. (Y\P,T)/(PT>)
4.2.2 Calibration and maintenance of flow rate at the working point of the sampler: GB/T15432-1995
Open the sampling cover of the sampling head, put a clean sampling filter membrane in the normal sampling position, and seal the interface of the orifice flowmeter with the sample head. Connect the pressure port of the orifice flowmeter to the differential pressure gauge. Turn on the power supply, turn on the sampler, and after it stops working, adjust the sampler flow rate so that the differential pressure value of the orifice flowmeter reaches the 4H value calculated by formula (7) (see Appendix B for the record table).
When calibrating the flow rate, ensure that the gas path is sealed and connected. After the flow calibration, if the edge contour of the dust on the filter membrane is unclear or the filter membrane is installed crookedly, it can cause If there is any leakage, recalibration should be performed. The sampler that has passed the calibration can be used for sampling, and the regulator status shall not be changed. 5. Total suspended particulate matter content test
5.1 Filter membrane preparation
5.1.1 Each filter membrane needs to be inspected with an X-ray film viewer. There shall be no pinholes or any defects. Number the two diagonals on the smooth surface of the selected filter membrane: print the sample number on the filter membrane for later use. 5.1.2 Place the filter membrane in a temperature and humidity chamber to equilibrate for 24 hours. The equilibrium temperature shall be any point between 15 and 30°C. Record the equilibrium temperature and humidity. 5.1.3 Weigh the filter membrane under the above-mentioned equilibrium conditions. The filter membrane of the large flow sampler shall be weighed accurately to 1 mg, and the filter membrane of the medium flow sampler shall be weighed accurately to (.1 mg, record the filter membrane volume Wc (g) 5.1.4 Place the weighed filter membrane flat in the filter membrane storage box. Do not bend or fold the filter membrane before sampling: 5.2 Place the filter membrane and sampler
5.2.1 Open the top cover of the sampling head and take out the filter membrane clip. Wipe the dust inside the sampler and the filter membrane clip with a clean dry cloth. 5.2.2 Place the numbered and weighed filter membrane with the velvet side facing up on the filter membrane support net, put the filter membrane clip on, align it, and tighten it to prevent air leakage. Install the sampling head cap, set the sampling time according to the sampler instructions, and start sampling. 5.2.3 After sampling, open the sampler head, gently remove the filter membrane with a key, face the sampling side inward, fold the filter membrane in half, and put it in a filter membrane bag with the same size. When taking out the filter membrane, if the filter membrane is found to be damaged, or the edge of the dust on the filter membrane is unclear, or the filter membrane is installed obliquely (indicating air leakage), the current sampling will be invalidated and re-sampling is required (see Appendix C for the record form). 5.3 Balanced weighing of membranes
5.3.1 The dust membrane is placed in a temperature and humidity chamber at the same temperature and humidity as the clean filter membrane. Balance for 24 hours. 5.3.2 Under balanced conditions, weigh the mother filter membrane, the large flow sampling filter membrane to an accuracy of 1 mg, and the flow sampler filter membrane to an accuracy of 0.1 mg. Record the weight of the filter membrane W. (g) (see Appendix [) for the record form). The weight gain of the filter membrane. The large flow filter membrane is not less than 100 mg, and the medium flow filter membrane is not less than 10 mg:
5.4 Calculate
Total suspended particulate matter content (μg/m2): Q Xt
Formula: t——Cumulative sampling time, in;
Q——Average flow distance of the sampler, Formula (3) or Formula (4)2 or Qm calculated value: K—constant.For large flow sampler, K=1×10°; for medium flow sampler, K1×10\,6Reproducibility of the test methodbZxz.net
When two total suspended particulate matter samplers are placed at a distance of not less than 4m and not less than 2m, the total suspended particulate matter content is determined by sampling at the same time, and the relative error is not greater than,
GB/T15432—1995
Appendix A
Calibration requirements for orifice flowmeters
(Supplement)
Within the base range of large flow or medium flow orifice flowmeters, seven points are selected and calibrated by standard Roche flowmeter and bell-accumulator gas meter respectively. The final result is given by regression equation (A1). Y=Q+A
Correction term Y(Pa)?
Where: T--standard temperature, 273 K;
--ambient temperature during calibration, K;
pressure difference measured by orifice flowmeter, Pa t
--slope;
A--intercept;
Pn--standard pressure, (101.3 kPa)
P--ambient pressure during calibration, kPa
Sampler
..(A2)
--flow rate converted to standard conditions, m/rnin for large flow orifice flowmeter; L/min for medium flow orifice flowmeter. Appendix B
Calibration record sheet for total suspended particulate matter sampler using orifice flowmeter (reference)
Environmental monitoring
Sampler working
Point flow
m'/min)
Orifice flow
Meter number
Monthly average
Atmospheric pressure
Note: (1) m/rin The flow rate of the large flow sampler is 1000L/min, the flow rate of the medium flow sampler should be L/min, the hole difference is calculated and the calibration period is difficult. Additional instructions: Sampler Filter membrane number GB/T15432-1995 Appendix C Total suspended particulate matter on-site sampling record (reference) Appendix D Total suspended particulate matter concentration analysis record (reference) Tester Standard flow rate m*/min Sample time This standard is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. This standard is drafted by the China National Environmental Monitoring Center. The main drafters of this standard are Li Ancheng and Liu Yanhua. The total sampling volume is entrusted by the State Environmental Protection Administration to the China National Environmental Monitoring Center for interpretation. Final film weight: dust film Environmental Monitoring Station Environmental Monitoring Station Total suspended particulate matter concentration
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