65
5 Source Testing
TABLE 5.1
Code of Federal Regulations Source Test Methods
Method Description
1 Sample and velocity traverses for stationary sources
1A Sample and velocity traverses for stationary sources with small stacks or ducts 2 Determination of stack gas velocity and volumetric flow rate (type-S pitot tube) 2A Direct measurement of gas volume through pipes and small ducts
2B Determination of exhaust gas volume flow rate from gasoline vapor incinerators 2C Determination of stack gas velocity and volumetric flow rate in small stacks or ducts
(standard pitot tube) 2D
2E 2F 2G 2H
Measurement of gas volumetric flow rates in small pipes and ducts Determination of landfill gas production flow rate
Determination of stack gas velocity and volumetric flow rate with three-dimensional probes Determination of stack gas velocity and volumetric flow rate with two-dimensional probes Determination of stack gas velocity taking into account velocity decay near the stack wall 3 Gas analysis for the determination of dry molecular weight
3A 3B 3C
Determination of oxygen and carbon dioxide concentrations in emissions from stationary sources (instrumental analyzer procedure)
Gas analysis for the determination of emission rate correction factor or excess air Determination of carbon dioxide, methane, nitrogen, and oxygen from stationary sources 4 Determination of moisture content in stack gases
5 Determination of particulate matter emissions from stationary sources
5A Determination of particulate emissions from the asphalt processing and asphalt roofing industry
5B Determination of nonsulfuric acid particulate matter from stationary sources
5C Reserved
5D Determination of particulate emissions from positive pressure fabric filters
5E Determination of particulate emissions from the wool fiberglass insulation manufacturing industry
5F Determination of nonsulfate particulate matter from stationary sources
5G Determination of particulate emissions from wood heaters (dilution tunnel sampling location)
5H 5I
Determination of particulate emissions from wood heaters from a stack location Determination of low level particulate matter emissions from stationary sources 6 Determination of sulfur dioxide emissions from stationary sources
6A Determination of sulfur dioxide, moisture, and carbon dioxide emissions from fossil-fuel combustion sources
6B Determination of sulfur dioxide and carbon dioxide daily average emissions from fossil-fuel combustion sources
6C Determination of sulfur dioxide emissions from stationary sources (instrumental analyzer procedure)
7 Determination of nitrogen oxide emissions from stationary sources
7A Determination of nitrogen oxide emissions from stationary sources—ion chromatographic method
7B Determination of nitrogen oxide emissions from stationary sources (ultraviolet spectrophotometry)
(Continued)
TABLE 5.1 (Continued)
Code of Federal Regulations Source Test Methods
Method Description
7C Determination of nitrogen oxide emissions from stationary sources—alkaline- permanganate/colorimetric method
7D Determination of nitrogen oxide emissions from stationary sources—alkaline- permanganate/ion chromatographic method
7E Determination of nitrogen oxide emissions from stationary sources (instrumental analyzer procedure)
8 Determination of sulfuric acid mist and sulfur dioxide emissions from stationary sources 9 Visual determination of the opacity of emissions from stationary sources
9 Alt. 1 Determination of the opacity of emissions from stationary sources remotely by LIDAR 10 Determination of carbon monoxide emissions from stationary sources
10A Determination of carbon monoxide emissions in certifying continuous emission monitoring systems at petroleum refineries
10B Determination of carbon monoxide emissions from stationary sources
11 Determination of hydrogen sulfide content of fuel gas streams in petroleum refineries 12 Determination of inorganic lead emissions from stationary sources
13A Determination of total fluoride emissions from stationary sources—SPADNS zirconium lake method
13B Determination of total fluoride emissions from stationary sources—specific ion electrode method
14 Determination of fluoride emissions from potroom roof monitors for primary roof monitors for primary aluminum plants
14A Determination of total fluoride emissions from selected sources at primary aluminum production facilities
15 Determination of hydrogen sulfide, carbonyl sulfide, and carbon disulfide emissions from stationary sources
15A Determination of total reduced sulfur emissions from sulfur recovery plants in petroleum refineries
16 Semicontinuous determination of sulfur emissions from stationary sources 16A Determination of total reduced sulfur emissions from stationary sources (impinger
technique) 16B
16C
Determination of total reduced sulfur emissions from stationary sources Determination of total reduced sulfur emissions from stationary sources
17 Determination of particulate emissions from stationary sources (in-stack filtration method) 18 Measurement of gaseous organic compound emissions by gas chromatography
19 Determination of sulfur dioxide removal efficiency and particulate, sulfur dioxide, and nitrogen oxides emission rates
20 Determination of nitrogen oxides, sulfur dioxide, and diluent emissions from stationary gas turbines
21 Determination of volatile organic compound leaks
22 Visual determination of fugitive emissions from material sources and smoke emissions from flares
23 Determination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans from stationary sources
(Continued)
due to mixing and diffusion. It is highly unlikely that gaseous pollutants will segre- gate in a moving gas stream. A simple probe can be used to withdraw a sample. Due care must be used to avoid pulling a sample from a nonrepresentative location, such as just downstream of an injection point.
The primary consideration for gaseous pollutant sampling is that the sample is not contaminated, or decontaminated, by incompatibility with the materials of the sam- pling device or container. Teflon, stainless steel, and glass sample lines and containers often are used to avoid reactions with pollutants.
5.3.2 VELOCITYAND PARTICULATE TRAVERSES
Volumetric flow rate in a duct or stack is measured using a pitot tube to detect the difference between the static and dynamic pressure difference created by the velocity head at several points in the duct. Details of the tip of a pitot tube are shown TABLE 5.1 (Continued)
Code of Federal Regulations Source Test Methods
Method Description
24 Determination of volatile matter content, water content, density, volume solids, and weight solids of surface coatings
24A Determination of volatile matter content and density of printing inks and related coatings
25 Determination of total gaseous nonmethane organic emissions as carbon
25A Determination of total gaseous organic concentration using a nondispersive infrared analyzer
25B Determination of total gaseous organic concentration using a nondispersive infrared analyzer
25C Determination of the nonmethane organic compounds (NMOC) in MSW landfill gases 25D Determination of the volatile organic concentration in waste samples
25E Determination of vapor phase organic concentration in waste samples 26 Determination of hydrogen chloride emissions from stationary sources
26A Determination of hydrogen halide and halogen emissions from stationary sources—
isokinetic method
27 Determination of vapor tightness of gasoline delivery tank using pressure-vacuum test 28 Certification and auditing of wood heaters
28A Measurement of air to fuel ratio and minimum achievable burn rates for wood-fired appliances
29 Determination of metals emissions from stationary sources
30A Determination of total vapor phase mercury emissions from stationary sources (instrumental analyzer procedure)
30B Determination of total vapor phase mercury emissions from coal-fired combustion sources using carbon sorbent traps
in Figure 5.1. The measured pressure difference is used to calculate velocity. The key is to position the pitot tube at the correct points in the duct, so that the average veloc- ity is determined. This is done by positioning the pitot tube at the centroid of equal- area segments of the duct. Method 1 (Code of Federal Regulations) provides tables for probe positions based on this principle. Figure 5.2 is an example of sampling points for a circular stack cross section. Figure 5.3 is an example for a rectangular duct. Note that the two lines of sampling points lie at 90°. For a circular duct, this requires at least two sampling ports at 90°. For small diameter stacks, the pitot tube can reach across the stack to pick up the points on the far side. For large diameter stacks, it is easier to reach no more than half way across the stack, so four sampling ports are provided to allow shorter sampling probes.
Similarly, because each sampling position is representative of a small area of the duct or stack, particulate samples are withdrawn at the same traverse points at which velocity measurements are made. However, because particles do not neces- sarily follow the streamlines of gas flow and because gravity can act on particles in a horizontal duct, Method 1 recommends more traverse points for particulate sampling than for a simple velocity traverse. The minimum number of sample points for traverses depends on the proximity of the test port to flow disturbances in the
1.90–2.54 cm (0.75–1.0 in.)
7.62 cm (3 in.)
FIGURE 5.1 Pitot tube for velocity measurement.
duct, and to a lesser extent, the duct size. The minimum number of sample points for a velocity traverse is illustrated in Figure 5.4. The minimum number of samples to be taken for a particulate traverse is illustrated in Figure 5.5.
5.3.3 ISOKINETIC SAMPLING
Extracting a particulate sample from a moving gas stream using a probe in a duct requires that the sample be taken at the same velocity as the gas flow, that is, isoki- netically. If the velocity of the sample is higher than that of the gas flow, then excess gas moving toward the probe will divert toward the probe and be collected with the sample. Meanwhile, particles with sufficient momentum will tend to continue travel- ing in a straight line, leaving the gas flow streamlines and will not be carried into
3 × 3 4 × 3 4 × 4 5 × 4 5 × 5 6 × 5 6 × 6 7 × 6 7 × 7 Matrix 9
12 16 20 25 30 36 42 49 Points
FIGURE 5.3 Traverse point locations for a rectangular duct.
29.5%
4.4%
14.7%
85.3%
70.5%
FIGURE 5.2 Traverse point locations for a round duct. The stack cross section is divided into 12 equal areas with the location of traverse points indicated.
the sampling probe, as illustrated in Figure 5.6a. This produces a sample that, after measuring the collected gas volume and weighing the collected particulate filter, has an erroneously low particulate concentration. Similarly, if the sample velocity is too low, excess gas is diverted away from the probe, while particles are carried into the probe, as illustrated in Figure 5.6b, resulting in an erroneously high particulate concentration.
2 30 25 20 15 10 Minimum number of traverse points
5
0 3 4
Duct diameters downstream from flow disturbance (Distance B)
5 6
16 20
12
9 (Rectangular) 25 (Rectangular)
8 (Round) 12 in. > dia > 24 in.
Dia > 24 in.
7 8 9
Gas flow Test port
Disturbance Disturbance
A
B
10
0.5 1.0
Duct diameters upstream from flow disturbance (Distance A)
1.5 2.0 2.5
24 (Round)
FIGURE 5.5 Minimum number of sample points for a particulate traverse.
2 25 20 15 10
Minimum number of traverse points 5
0 3 4
Duct diameters downstream from flow disturbance (Distance B)
5 6
16
12
9 (Rectangular) 8 (Round) 12 in. > dia > 24 in.
Dia > 24 in.
7 8 9
Gas flow Test port
Disturbance Disturbance
A
B
10
0.5 1.0
Duct diameters upstream from flow disturbance (Distance A)
1.5 2.0 2.5
FIGURE 5.4 Minimum number of sample points for a velocity traverse.
In Figure 5.6c is isokinetic sampling where the sampling flow rate is equal to the gas flow rate. This is the ideal sampling flow rate. Here the parallel flow streams flow into the sample inlet carrying with them particles of all diameters capable of being carried by the stream flow.
The correct isokinetic sample flow rate is determined by conducting a velocity traverse prior to collecting a particulate sample. During the particulate sample, the collected gas volume is measured with a gas meter. After the sample is taken and as data are being evaluated, the sample velocity as a percentage of gas velocity is determined and reported as a quality check on the particulate sample.
Vgas Vsample
Vsample
Vsample (a)
(b)
(c)
Sample probe
Vgas
Vgas
FIGURE 5.6 Reason for isokinetic sampling: (a) Vgas < Vsample; (b) Vgas > Vsample; (c) Vgas = Vsample.
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