§ 1066.630 - PDP, SSV, and CFV flow rate calculations.

§ 1066.630 PDP, SSV, and CFV flow rate calculations.

Cross Reference

Link to an amendment published at 89 FR 28212, Apr. 18, 2024.

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.

(a) PDP.

(1) Based on the speed at which you operate the PDP for a test interval, select the corresponding slope, a_1, and intercept, a_0, as determined in § 1066.625(a), to calculate PDP flow rate, v̇, as follows:

Where:

f_nPDP = pump speed.

V_rev = PDP volume pumped per revolution, as determined in paragraph (a)(2) of this section.

T_std = standard temperature = 293.15 K.

p_in = static absolute pressure at the PDP inlet.

T_in = absolute temperature at the PDP inlet.

p_std = standard pressure = 101.325 kPa.

(2) Calculate V_rev using the following equation:

p_out = static absolute pressure at the PDP outlet.

Example:

a₁ = 0.8405 m³/s

f_nPDP = 12.58 r/s

p_out = 99.950 kPa

p_in = 98.575 kPa

a₀ = 0.056 m³/r

T_in = 323.5 K

V_rev = 0.063 m³/r

v̇= 0.7079 m³/s

(b) SSV. Calculate SSV flow rate, v̇, as follows:

Where:

C_d = discharge coefficient, as determined based on the C_d versus Re^# equation in § 1066.625(b)(2)(viii).

C_f = flow coefficient, as determined in § 1066.625(b)(2)(ii).

A_t = venturi throat cross-sectional area.

R = molar gas constant.

p_in = static absolute pressure at the venturi inlet.

T_std = standard temperature.

p_std = standard pressure.

Z = compressibility factor.

M_mix = molar mass of gas mixture.

T_in = absolute temperature at the venturi inlet.

Example:

C_d = 0.890

C_f = 0.472

A_t = 0.01824 m²

R = 8.314472 J/(mol·K) = 8.314472 (m²·kg)/(s²·mol·K)

p_in = 98.496 kPa

T_std = 293.15 K

p_std = 101.325 kPa

Z = 1

M_mix = 28.7789 g/mol = 0.0287789 kg/mol

T_in = 296.85 K

V̇ = 2.155 m³/s

(c) CFV. If you use multiple venturis and you calibrated each venturi independently to determine a separate calibration coefficient, K_v, for each venturi, calculate the individual volume flow rates through each venturi and sum all their flow rates to determine CFV flow rate, V̇. If you use multiple venturis and you calibrated venturis in combination, calculate V̇ using the K_v that was determined for that combination of venturis.

(1) To calculate V̇ through one venturi or a combination of venturis, use the mean K_v you determined in § 1066.625(c) and calculate V̇ as follows:

Where:

K_v = flow meter calibration coefficient.

T_in = temperature at the venturi inlet.

p_in = absolute static pressure at the venturi inlet.

Example:

K_v = 0.074954 m³·K^0.5/(kPa·s)

p_in = 99.654 kPa

T_in = 353.15 K

V̇= 0.39748 m³/s

(2) [Reserved]

[81 FR 74211, Oct. 25, 2016]