API MPMS 12.2-1981 pdf free download
API MPMS 12.2-1981 pdf free download.Manual of Petroleum Measurement Standards Chapter of Petroleum Quantities.
In this equation Cp is calculated from Equation 9. When this volume is in如m temperabume conected to 60F using Equatioo 7, the value of Co taken from the appropriate table also corrects the volume for tbe change in pressure from P。 at measurement teperature, to equilibrium pressure at the standard temperatune of 60F. It should be noted that while P. at measurement temperaoure T may be higher than stand- ard atmospberic pressure (14.73 pounds per square inch absolute), equilibrium pressure at 60F may have fallen to attmospberic pressure or less. As noted under Equation 9, the distinction between a low vapor pressure liquid and a high vapor pressure liquid depends on wbether its equilib- rium pressure is less or grcater than atmospberic pressure at measurement temperatue. 12.2.5.5 COMBINED CORRECTION FACTOR (CCF) The recommended method for correcting volhumes by two or more correction factors is to first obtain a CCF (combined correction factor) by mutiplying the individual correction factors together in a set soquence, rounding at each step. Only then muliply the volume by the CCF. The set sequence is MF, Ca, Cg, Ca, Cp, and Cw, omiting any unused factors. 12.2.6 Calculation of the Volume of Provers 12.2.6.1 PURPOSE AND IMPUCATIONS The purpose of calibrating a prover is如o determine is base volume. Tbe procedures to be used are described in Chapter 4, Sections 2 and 3, of this manual. Base volume is expressed in barrels or gallons, both of which are multiples of the cabic inch. Whereas the cubic inch does not vary with temperature or pressure, tbe volume of a metal prover does vary. Therefore, the staterment of the base vohume of a prover or volumetric standard bas to specifty standard conditions, amely 60F and atmpospberic pressure.
In tbe 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 B1, Appendix B). The foal subscripts mean“p” for prover and *M”” for measure. Thus, the following steps are perfommed: 1. The votume 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 Co.,; the value for which can be found in Chapter 11.4.2, and dividing by Cp, the value of which can be computed from Equatioo 10 using F for water. 2. The volume so determined must then be corrected for thermal expansion of the field standard shell at the measuring temperature by multiplying the certified volume by Cam (see Equation 3). 3. Fnally, the measured volume of the prover so calculated must be corrected for both temperabure and pressure effects on the prover pipe in order to obtain the base volume, which is the equivalent volurme at standard conditions. These cor- rections require dividing by Ca and Cp, respectively. In calculating the values of Co and C. the physical cbarac- teristics of the prover metal must be known. Because an accuracy greater than 1 part in 10,000 is desirable in prover base volumes, determine all conection factor values to six decimal places. In practice, when several test measures are flled, the calculation is perfommed acording to Equation B6 in Appendix B in the manner specified in the following example (12.2.6.4.3).
The total of the values in Column 6 of Figure 2 is 1001.561 gallons, which is at 80.7*F. Each withdawal has been corrected to 80.7°F by the correction factor shown in Column 5. Since the feld standards and the prover being calibrated are made of the same material (mild steel) and the weighted temperature difference is not greater than 3°F. Do 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 cali- bration. If the reading on the top neck was. for exanple. 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 9/16 or 0.563 inch. An altemative would be to move the zero mark on the bottom neck scale upwards by 9/16 inch. Both scales should be resealed afterwards.
