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API MPMS 3.6:2001(2017) pdf download

API MPMS 3.6:2001(2017) pdf download.Manual of Petroleum Measurement Standards Chapter 3-Tank Gauging Section 6—Measurement of Liquid Hydrocarbons by Hybrid Tank Measurement Systems.
h. The ATt should be verified in accordance with the pmecdurc for subsequent verilication of calibration described in dPMS Chapter 7. hut using the tolerance sçecihcd in Table 3 of this standani
C.The pressure scnsoe’ transnsincrtsi tern and lincanty stability should be serilicil in accordance with ihc method sd fonh in 10.4.1 tolerances.
10.5.2 Regular Verification of HTMS Density
Density comparison o HTMS density with product density determined by manual methods is optional in ass-based custody lranstcr applicaians. This companson. if desircd. should he made in accordance with 10,4.2.
10.5.3 Frequency of Regular Verification
regular verification of the niajor components.ineasurrmengs of the HTMS used in mass-based custody transfer applications should be as Inflows:
a. ATG—A newly installed or repaired ATO should be yen&d once per quaner, lIthe performance of the ATG is stable. the frequency may be reduced to once esery six months vided that density performed (WI a quiirledy bus&,. and statistical data indicates the overall system is stable.
b. ATr—A newly installed or repaired AlT should be on the sale frequency as the AT(1
c. Pressure Scnsorl s —The pressure scnsoriransmitter( s) zero and linearity stability should be vcritied quarterly following initial verification. If the pressure sensor’ Lmansmittczlsi linearity is stable, the frcqucncy of verification of linearity may he reduced to once per six months.
d. Product Density—The comparison of product density by an HTMS with density determined by manual methods is optional. The exceprion to this is if the density comparison is to he used as a basis for reducing the frequeni. of the ATG subsequent verification (10.5.3(a) above). in which case thedensity comparison should be done quarterly.
Note: Morc firoquent oomparison of product density will insure carlydetection of probllcms in the ATG,ATT, or pressure senso/transmit-ter(S)., and it provides valable statisticaill data
Al General
This APPENDIX describes the calculations perlbrmed by the HTMS hybrid processor to compute the density of the tank contents and other variables. Specific calculations and features which may be unique to a particular manufacturer’s design of an I-ITMS are not included (e.g.. pressure sensor lineariiation formulae).
Symbols used in this APPENDIX are illustrated in Figure
IIFMS calculations are the same for all lank geometries. including floating roof tanks.
For atmospheric tanks, in-tank vapor density and ambient air densities have only secoixi order etTects on the calculated variables. They can be considered constant, or for high accuracies can he calculated. In-tank vapor density can be calculated using the gas equation of state from absolute vapor pressure and absolute vapor temperature together with the vapor relative density.
Ambient air density can be calculated using the gas equation of state from absolute ambient pressure and absolute ambient temperature. Changes in ambient air density have only a second order clkct on the observed density.
All sensor input data presented to the hybrid processor should be essentially synchronous.
All values to be substituted in the equations in this Appendix may be in either US Customary (USC) or SI units. (see MPMS Chapter 15). Refer to Table A-I.
If values are obtained in other units, they should be convei-tcd into values in either of the tillowing USC or SI units.


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