TE-PNY1123 23 Operations Manual
Example Calculations
The following example problems use data from the attached calibration
worksheet. After all the sampling site information, calibrator information, and
meteorological information have been recorded on the worksheet, standard air
flows need to be determined from the orifice manometer readings taken during
the calibration using the following equation:
1. Qstd = 1/m[Sqrt((H20)(Pa/760)(298/Ta))-b]
where:
Qstd = actual flow rate as indicated by the calibrator orifice, m3/min
H20 = orifice manometer reading during calibration, (
Ta = ambient temperature during calibration, K ( K = 273 + oC)
298 = standard temperature, a constant that never changes, K
Pa = ambient barometric pressure during calibration, mm Hg
760 = standard barometric pressure, a constant that never changes, mm Hg
m = Qstandard slope of orifice calibration relationship
b = Qstandard intercept of orifice calibration relationship.
Note that the ambient temperature is needed in degrees Kelvin to satisfy the
Qstd equation. Also, the barometric pressure needs to be reported in
millimeters of mercury. In our case the two following conversions may be
needed:
2. degrees Kelvin = [5/9 (degrees Fahrenheit - 32)] + 273
3. millimeters of mercury = 25.4(inches of H2O/13.6)
Inserting the numbers from the calibration worksheet run point number one
we get:
4. Qstd = 1/1.47574[Sqrt((5.7)(757/760)(298/293)) - (-.00613)]
5. Qstd = .6776261[Sqrt((5.7)(.9960526)(1.0170648)) + .00613]
6. Qstd = .6776261[Sqrt(5.7771295) + .00613]