# API MPMS 12.2:1981 pdf download

API MPMS 12.2:1981 pdf download.Manual of Petroleum Measurement Standards Chapter 12- Calculation of Petroleum Quantities.

12.2.6.3 RULE FOR ROUNDING—PROVERS

in calcubting a prover volume, determine individual correction factors to six decimal places by using the appropriate formuk interpolation will be required for Ce,. Record the combined correction factor (CCF) rounded to six decimal places. Multiply the sum of the measured volumes, each of which has been individually adjusted to starting temperature. by the CCF, arid report the base volume so determined to five significant digits. Round the corrected individual withdrawal volumes to the sai’ number of significant digits as the uncorrected volumes.

12.2.6.4 CALCULATION OF BASE VOLUMES

The procedure for calibrating pipe provers will be found in Chapter 4. Section 2. The following subsections, 12.2.6.4.1 through 12.2.6.4.4. specify the calcubtion of the base volume of a pipe prover calibrated by the water draw method.

12.2,6.4.1 Initial Step

During the calibration of a pipe prover. the temperanire and pressure of the water in the piover at the stan of calibration e observed and recorded. Likewise, the ternperannes of the individual withdrawals into field standards are observed and recorded.

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,1,, the value of which can be computed from Equation 10 using F for waler.

2. The volumt so detrmiined 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 V2nd2rd conditions. These corrections 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 measures are filled, the calculation is performed to Equation B6 in Appendix B in the nnner specified in the following example (12.2.6.4.3).

12.2.6A.3 Example Calculation for a Pipe Prover

The form or record used for a water draw calibration of a pipe prover must mk provision for at least the inforrzzation shown in Figure 1. The values shown are for example only,

The total of the values in Column 6 of Figure 2 is 1001.561 gallons, which is at 80.7°F. Each withdrawal has been coiected to 80.7°F by the correction factor shown in Column 5. Since the field standards and the prover being calibrated are made of the same mazeriai (mild steel) and the weighted temperature difference is not greater than 3°F. no further correction is needed to bring the calibrated volume of the prover to 60°F, as the certified volumes of field standards were adjusted to 60°F at the time of their calibration. If the reading on the top neck was, for example. 1001.000 gallons at the start of calibration and as the true volume is now known to be 1001.561 gallons. the top scale will have to be moved downwards 0.561 gallons. If the neck contains 1 gallon per inch (which is usually the case) the top scale will be moved downwards 9116 or 0.563 inch. An alternative would be to move the zero mark on the bottom neck scale upwards by 9116 inch. Both scales should be resealed afterwards.