This section describes the equations for calculating flow rates from various flow meters. After you calibrate a flow meter according to § 1066.625 , use the calculations described in this section to calculate flow during an emission test. Calculate flow according to 40 CFR 1065.642 instead if you calculate emissions based on molar flow rates.
Where:
fnPDP = pump speed.
Vrev = PDP volume pumped per revolution, as determined in paragraph (a)(2) of this section.
Tstd = standard temperature = 293.15 K.
pin = static absolute pressure at the PDP inlet.
Tin = absolute temperature at the PDP inlet.
pstd = standard pressure = 101.325 kPa.
EQ. 1066.630-2
Where:
pout = static absolute pressure at the PDP outlet.
Example:
a1 = 0.8405 m3 /s
fnPDP = 12.58 r/s
pout = 99.950 kPa
pin = 98.575 kPa
a0 = 0.056 m3 /r
Tin = 323.5 K
Where:
Cd = discharge coefficient, as determined based on the Cd versus Re# equation in § 1066.625(b)(2) (viii).
Cf = flow coefficient, as determined in § 1066.625(b)(2)(ii) .
At = venturi throat cross-sectional area.
R = molar gas constant.
pin = static absolute pressure at the venturi inlet.
Tstd = standard temperature.
pstd = standard pressure.
Z = compressibility factor.
Mmix = molar mass of gas mixture.
Tin = absolute temperature at the venturi inlet.
Example:
Cd = 0.890
Cf = 0.472
At = 0.01824 m2
R = 8.314472 J/(mol·K) = 8.314472 (m2·kg)/(s2·mol·K)
pin = 98.496 kPa
Tstd = 293.15 K
pstd = 101.325 kPa
Z = 1
Mmix = 28.7789 g/mol = 0.0287789 kg/mol
Tin = 296.85 K
V = 2.155 m3/s
Where:
Kv = flow meter calibration coefficient.
Tin = temperature at the venturi inlet.
pin = absolute static pressure at the venturi inlet.
Example:
Kv = 0.074954 m3·K0.5/(kPa·s)
pin = 99.654 kPa
Tin = 353.15 K
V= 0.39748 m3/s
40 C.F.R. §1066.630