API MPMS 3.6:2001 pdf download.Manual of Petroleum Measurement Standards Chapter 3- -Tank Gauging Section 6- -Measurement of Liquid Hydrocarbons by Hybrid Tank Measurement Systems.
Note 2: The acceptable wicertainty of the IITMS density is determined based on the impact on the uncertainty of the volume correction factor {VCF. or temperature effect on liquid. or Ctl).
Alternately, for non-stratified products, if an on-line densitonletcr is available and it has been recently calibrated against a reference traceable to NIST. the average density by the densitometer for a batch transferred into or out of the tank against the average density measured by the I ITMS for the batch can be compared. using the tolerances described above.
Note 3: If the tank content is a pure, homogeneous product (e.g.. some pure petrochemical Iiquidst and its reference dcnsity can be detennined accurately from physical science, and if it is well recogni7cd as an accurate representation of the density property of the product. then the density by the HTMS can be compared with this reference density.
9.4.2 Initial Field Verification of Mass-based HTMS Applications
A mass-based HTMS should be verified as ll1ows:
a. ATG—The ATG should be verified in accordance with the procedure for initial verification of calibration described in MPMS. Chapter 3.1 B. but using the appropriate tolerance for either custody transfer or inventory control, as specifIed in Table I of this standard.
b. ATT—The ATT should be verified in accordance with the procedure ftr initial verification of calibration described in MPMS. Chapter 7. but using the appropriate tolerance as specified in Table 3 of this standard.
c. Pressure Sensor(s)—The pressure sensors (including transmitters, if they are separate devices) affect the accuracy of the mass measurement, and should be eritied in accordance with the method set ftrth in Section 9.4.1(c). Table 2 summarizes the requirements on pressure sensor tolerances.
d. Density comparison of IITMS density with product density should be made in accordance with 9.4.1 Id).
IITMS mass transfer accuracy should be verified using the method described in MI’MS Chapter 16.2. Section 7.3.6.
Note: The tolerance set forth in MPMS Chapter 16.2 is for “transfer accuracy” and therefore the verification involves transfer of liquid into or out of the tank.
10 Regular Vent ication of HTMS
10.1 GENERAL
After commissioning and initial held verifIcation, an HTMS should be regularly verified in the field. This subsequent. or regular verification is also called “validation’.
The sections below cover post—commissioning I-ITMS verification and any necessary re-calibrations.
API MPMS 3.6:2001 pdf download
