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Reference Method for Source Testing: Measurement of Releases of Selected Semi-volatile Organic Compounds from Stationary Sources
Section 7: Calculations
- 7.1 Equations
- 7.2 Nomenclature
To simplify recording during a test, field data may be entered in the units for which the sampling equipment is designed. These values must be converted, if necessary, to the metric units specified in the applicable equations.
7.1 Equations (see Section 7.2 for Nomenclature)
7.1.1 Dry Gas Meter Volume
The total sample volume measured by the dry gas meter is corrected to reference temperature and pressure conditions (25°C and 101.3 kPa) using Equation 1. For a temperature-compensated dry gas meter (Tm)avg should be substituted by the temperature specified by the manufacturer.
7.1.2 Volume of Water Vapour
The volume of water vapour in the sack gas sample expressed at reference conditions (25°C and 101.3 kPa) is calculated by using Equation 2.
7.1.3 Moisture Content
The volumetric fraction of water vapour in the stack gas expressed at reference conditions (25°C and 101.3 kPa) is calculated using Equation 3.
For a saturated or suspersaturated stack, use a psychrometric chart to determine Bwo.
7.1.4 Absolute Stack Gas Pressure
The absolute stack gas pressure is calculated using Equation 4.
7.1.5 Stack Gas Molecular Weight
The stack gas molecular weight on a wet basis is calculated using Equation 5.
7.1.6 Stack Gas Velocity
The stack gas velocity measured at each traverse point is calculated using Equation 6.
The average stack gas velocity ((Us)avg) and stack gas temperature ((Ts)avg) for the test run are determined by averaging the velocities and temperatures respectively measured at the traverse points.
7.1.7 Volumetric Stack Gas Flow Rate
The average volumetric stack gas flow rate expressed on a dry basis and at reference conditions (25°C and 101.3 kPa) is calculated using Equation 7.
7.1.8 Isokinetic Variation
The isokinetic variation for each traverse points is calculated using Equation 8.
A test shall be considered valid when no more than 10% of the isokinetic values fall outside the range 90% to 110% and the average for all the traverse points Iavg falls within the range 90% to 110%.
7.1.9 Correction Factor
The pollutant concentrations expressed in this method must be corrected to a basis of 11% O2. The correction factor to express concentrations at 11% O2 is calculated using Equation 9.
7.1.10 Polychlorinated Biphenyl Emission Rates
The emission rate of polychlorinated biphenyls is calculated using Equation 10.
7.1.11 Concentrations of 2,3,7,8-TCDD Equivalent PCDDs and PCDFs
The concentration of 2,3,7,8-TCDD equivalent PCDDs and PCDFs corrected to 11% O2 is calculated using Equation 11. The weight of 2,3,7,8-TCDD equivalent PCDDs and PCDFs is determined from Figure 5.
Figure 5: Calculation of 2,3,7,8-T4CDD Equivalent PCDDs and PCDFs
7.2 Nomenclature
- As
- inside cross-sectional area of stack or duct, m2
- Bwo
- volumetric fraction of water vapour in the stack gas, dimensionless
- C2,3,7,8-T4CDD'
- concentration of 2,3,7,8-T4CDD equivalent PCDDs and PCDFs on a dry basis at reference temperature and pressure conditions corrected to 11% O2, ng/m3 at 11% O2
- CP
- S-type pitot tube coefficient, dimensionless
- ERPCBs
- emission rate of polychlorinated biphenyls, μg/h
- ΔHavg
- average pressure drop across orifice meter, kPa
- ΔH
- pressure drop across orifice meter for each traverse point, kPa
- Iavg
- average isokineticity for the test, (%)
- I
- isokineticity i.e., the ratio of the sampling velocity through the nozzle to the velocity of the undisturbed gas stream at each traverse point, dimensionless, (%)
- j
- traverse point number, dimensionless
- Md
- molecular weight of stack gases on a dry basis, kg/kmol
- Ms
- molecular weight of stack gases on a wet basis, kg/kmol
- MH2O
- molecular weight of water, 18 kg/kmol
- Nd
- inside diameter of the sampling nozzle, mm
- f11% O2
- correction factor to convert concentrations at dry and reference temperature and presure conditions to 11% O2, dimensionless
- %O2
- concentration of oxygen in the stack gas (dry basis), % by volume
- Ps
- absolute stack gas pressure, kPa
- Pbar
- barometric pressure at the sampling site, kPa
- ΔP
- pitot-tube velocity pressure reading at each traverse point, kPa
- Pref
- reference pressure, 101.3 kPa
- ΔPs
- static pressure of the stack gas, kPa
- Qs
- volumetric stack gas flow rate on a dry basis at reference temperature and reference pressure conditions, m3/h
- R
- universal gas constant, 8.31 kPa m3(kmol·K)-1
- t
- sampling duration for each traverse point, min
- (Ts)avg
- average of the absolute stack gas temperatures, K
- Ts
- absolute stack gas temperature at each traverse point, K
- (Tm)avg
- average of the absolute dry gas meter temperatures, K
- Tmi
- absolute temperature at the dry gas meter inlet for each traverse point, K
- Tmo
- absolute temperature at the dry gas meter outlet for each traverse point, K
- Tref
- reference temperature, 298 K
- (Us)avg
- average stack gas velocity, m/s
- Us
- stack gas velocity measured at each traverse point, m/s
- Vm
- volume of stack gas sample at dry gas meter conditions, m3
- (Vm)j
- volume of stack gas sample at dry gas meter conditions for each traverse point, m3
- (Vm)ref
- volume of stack gas sample at reference conditions, m3
- As
- volume of water vapour in the stack gas sample at reference conditions, m3
- WH2O
- weight of water vapour condensed in the impingers, g
- WPCBs
- weight of polychlorinated biphenyls collected in the semi-volatile organics sampling train, mg
- W2,3,7,8-T4CDD'
- weight of 2,3,7,8-TCDD equivalent PCDDs and PCDFs collected in the semi-volatile organics sampling train, ng
- γ
- dry gas meter calibration factor (ratio of the wet test meter volume to the dry test meter volume) dimensionless
- 128.95
- proportionality constant (m/s)(K-1·kg/kmol)½
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