API MPMS 4.8:2021 pdf download

API MPMS 4.8:2021 pdf download.Manual of Petroleum Measurement Standards Chapter 4.8
Operation of Proving Systems.
— accurnijalion of foreign material (such as wax) buildup in the meter:
— reprogramming of electronic based meters;
— seasonal temperature changes.
A new certification of a master meter prover shall occur before its next intended use when any one of the
following oonditions exists:
a) lithe calibration frequency (time period) calculated in Annex B is met or exceeded,
b) the maximum time interval of 12 months (1 year) has elapsed.
The master meter prover should be inspected periodically for general conditions. Numerous considerations determine how frequently a master meter prover should be recertified. They include but are not limited to:
a) the value (fiscal) of the metered liquids;
b) contractual or regulatory requirements;
C) usage, time, wear;
d) certification history;
e) alterations, repairs, or changes In operating conditions that affect the master meter factor.
NOTE Section 10.2 is applicable to master meters used for custody transfer applications, This section is not intended to define frequency for certification of master meters used for allocation applications.
11 Proving Methods
11.1 Volumetric Proving
With volumetric proving, the volume of fluid in the prover (reference quantity) is compared with the meter indicated volume to generate a meter factor. Common provers are:
a) displacement prover,
b) volumetric master meter prover,
C) volumetric tank prover.
d) gravimetric tank prover (inferred volume).
11.2 Direct Mass Proving
In direct mass proving, the mass of liquid ri the prover (reference quantity) is physically measured by weight. The mass measured by the prover Is then compared with the mass measured by the meter to generate a mass meter factor (prover masslmeter mass). The common methods used are as follows.
a) Gravirnetnc—The reference quantity of liquid Is weighed on a scale and compared with a meters Indication of mass.
1) A mass meter is proved against a gravimetric lank and scale system. The scale shall be traceable to a national rnetrology institute with a lower uncertainty than the meter,
2) The test liquid flows through the mass meter and is collected in a tank on a we.gh scale,
3) The mass readout from the mass meter is compared with the weigh scale mass indication, corrected for
buoyancy effect.
b) Mass Master Meter—The reference quantity of liquid is obtained from a mass master meter and compared with a meter Nidication of mass. Refer to API MPMS Ch. 4.5 or API MPMS Ch. 5.6.
1) A mass meter proved against a mass master meter. The mass master meter has been proved against a direct or inferred mass proving system traceable to a national metrology Institute with a lower uncertainly than the meter. The test liquid flows through the mass meter and the mass master meter.
2) The mass readout from the mass meter is compared with the mass master meter Indication to compute a mass meter factor.
11.3 Inferred Mass Proving
In an Inferred mass proving, the mass of the fluid m the prover (reference quantity) Is calculated rather than physically measured as in 11.2. The mass of the fluid In the prover is calculated by multiplying the prover volume and the fluid density at prover conditions The BPV Is corrected using CTSP and CPSP to flowing conditions. (CTLP and CPLP are not used.) The prover mass is compared with the meter indicated mass to generate a mass meter factor. The accuracy of this method is equally dependent upon the accuracy of both the prover volume and the pover density measuremeni
The volume for inferred mass proving should be determined by one of the provers in 11.1
The selection of a method to determine the fluid density in the prover is critical to calculating the correct meter factor. Several methods to determine density can be used. Refer to 7.5 for methods of measuring flowing density. These methods should be closety reviewed as to their accuracy and ability to measure the density under the conditions (pressure and temperature) present at the prover. For inferred mass proving, the preferred method for determining the fluid density at the prover is to use an online density meter on the prover. The density meter should be installed, operated, and calibrated per API MPMS Oh. 14.6 “l, The resulting output of the density meter should be averaged duong each prover run or pass,
When the density varies during a proving, it shall be averaged for each prover run or pass (averaged between the prover switches), The sampling frequency and the density averaging method also influence the overall accuracy of this method.