API MPMS 12.2:1981(2002) pdf download
API MPMS 12.2:1981(2002) pdf download.Manual of Petroleum Measurement Standards Chapter 12- Calculation of Petroleum Quantities Section 2- Calculation of Liquid Petroleum Quantities Measured by Turbine or Displacement Meters.
12.2.6.42 Corrections Applied to Measured Volumes
In the water draw calibration procedure, the volume observed in the field standards must be subjected to certain corrections in order to determine the base volume of the prover (see Equation B 1, Appendix B). The final subscripts mean “p” for prover and “M” for measure.
Thus, the following steps are performed:
1. The volume of water in a field standard must be corrected for the effect of temperature and pressure on the liquid to determine what volume the water occupied when it was in the prover; this is done by multiplying the volume by C the value for which can be found in Chapter 11.4.2, and dividing by C,,, the value of which can be computed from Equation 10 using F for water.
2. The volume so detrruiined must then be corrected for thermal expansion of the field standard shell at the measuring temperature by multiplying the certified volume by C (see Equation 3).
3. Finally, the measured volume of the prover so calculated must be corrected for both temperature and pressure effects on the prover pipe in order to obtain the base volume, which is the equivalent volume at 9nd2rd conditions. These coyrections require dividing by C,., and C11,, respectively. In calculating the values of C11 and C,, the physical characteristics of the prover metal must be own. Because an accuracy greater th2n 1 part in 10,000 is desirable in prover base volumes, determine all correction factor values to six decimal places. In practice, when several test sures are filled, the calculation is performed according to Equation B6 in Appendix B in the manner specified in the following example (12.2.6.4.3). –
In some metering applications, the variables MF and C in Equation 17 are combined into a “composite meter factor.” When such a composite meter factor is applied to the indicated volume of a temperature compensated meter (which automatically applies C), the metered quantity in baxrels at standard conditions can be obtained by multiplying indicated volume by the composite MF alone.
It is important not to confuse a standard meter factor (Equation 15) with a composite meter factor. They are not interchangeable.
12.2.7.2 HIERARCHY OF ACCURACIES
Meter factors fit into the hierarchy of accuracies between calibrated prover volumes (12.2.6) and calculation of rneasiuement tickets (12.2.8). Thus temperature readings for proving should be averaged and then rounded to the nearest 0.TF. Pressure readings for proving should be averaged and then rounded to the nearest scale division, a pressure gage with its appropriate range having previously been selected.
12.2.7.3 RULE FOR ROUNDING—MT.R FACTORS
In calcnlating a meter factor, deteimine the numerator and &DoImn2tor values sep2ntely, with each rounded to at least five significant digits. In intermediate caIcul2lions determine individual correction factors to four decimal places. Multiply individnal correction factors together, rounding to four decini2l places at each step (for each mimerator and &nolTlin2tor), and record the combined correction factor (CCF) rounded to four decimal places. Divide corrected prover volume by corrected meter volume, and round the resulting meter factor to four decimal places.
12.2.7.4 CALCULATION OF ThE METER
FACTOR USiNG A TANK PROVER AND A DISPLACEMENT METER
In calculating a stanrd meter factor use Equation 15.
termine the n by re2ding the upper gage glass of the nk the indicated volume should be recorded to the nearest thoncandzh of a barrel. if the bottom gage glass was not at zero before the proving run was started, its ieading must be 2dded to or subtracted from (as the case may be) the upper gage glass reading, and the algebraic sum recorded as the indicated volume.
To alcuI2?a’ a meter factor, both prover and meter volumes must be in the same units. If the meter registers in barrels, record to 0.001 barrels, or if in gallons to the nearest 0.01 gallon, or to five significant digits.
