API MPMS 4.8-2021 pdf free download

API MPMS 4.8-2021 pdf free download.Operation of Proving Systems.
6 Frequency of Meter Proving The frequency required for proving varies from several times a day to twice a year or even longer depending upon the reasons listed in Section 5. Other reasons are: a) value of the liquid, b) cost/beneft to prove, c) meter proving history, d) meter system stability, e) variations of operating systems. The actual proving frequency is dependent upon the contract or procedures established by the operator of the metering system. This standard does not defne proving frequency of meters. In general, the proving frequency for a new system starts with short intervals and may be extended to longer intervals as confdence increases in the system. The operator should specify the interval of time or a quantity of throughput, after which the meter should be proved again. In a situation where custody transfer accuracy is not required, and where viscosity and temperature do not vary too widely, it may be sufcient for meters to be re-proved at specifed intervals, such as every month or two when the metering system is new, extending to once in six or perhaps 12 months when the reliability of the meter system has been established. 7 General Considerations for Meters and Provers 7.1 General The meter should be operated within its performance curve, and the prover should be operated within its fow rate limitations. The meter should be proved as close as practical to the same conditions under which it normally operates. Meter performance is dependent upon process conditions. Therefore, during proving it is essential that fow rate be maintained within the normal operating fow range of the meter. 7.2 Data Recording Manually recording data during the prove limits the ability to track changes in operating conditions over the proving and may increase the uncertainty of the meter factor. For manual data recording, it is necessary to prove under the following conditions to minimize meter factor uncertainty:
7.3 Temperature and Pressure Measurements 7.3.1 General Accurate temperature and pressure measurements are necessary for all types of proving, except direct mass proving. Proving systems with automated (computerized) recording of the required meter and prover data reduces proving uncertainty as compared with manual measurements. These two operating conditions should be stabilized (in equilibrium) for best proving results. Stability of these conditions during the proving reduces meter factor uncertainty. 7.3.2 Location Prover temperature and pressure measurement shall be taken at locations as described in API MPMS Ch. 4.2, API MPMS Ch. 4.4, and API MPMS Ch. 4.5 as applicable. Meter temperature and pressure measurement shall be taken at locations as described in API MPMS Ch. 5.1 as applicable. 7.3.3 Accuracy Temperature and pressure values shall be within the ranges of the appropriate volume correction equations/ tables (API, GPA). Thermometers or temperature transducers used for proving shall be the highest practical resolution as recommended in API MPMS Ch. 7 [10] . Pressure gauges or pressure transducers shall be selected with a resolution that enables the recording of pressure values as required in API MPMS Ch. 12.2. 7.3.4 Discrimination The proving temperature and pressure values shall be recorded as required in API MPMS Ch. 12.2.
7.6 Proving Meters with Pulse Output 7.6.1 General Pulse-generating meters are the most commonly used devices. The output is pulses per unit quantity (pulses/ cubic meter, pulses/gallon, pulses/barrel, pulses/pound, etc.). The electronic pulses from the meter should be continuous and produce a nonintermittent (non-burst type) signal. 7.6.2 Noncomputational Technologies Some meter technologies use the energy of the fuid stream to produce electronic pulses that are proportional to the rate of fow. Typical noncomputational meters are displacement meters and turbine meters. 7.6.3 Computational Technologies Electronic fow meter technologies use sampling methodologies to determine fow rate. The meter pulse output is a result of computations from the electronic sampling. At any instant in time the meter pulse output will represent fow (or quantity throughput) that has already occurred (i.e. the fow pulses lag the measured fow). Computational technologies include Coriolis and ultrasonic meters, and any meter using computing electronics to generate a pulse. These meters can be proved using the techniques described by this chapter, but because of the computer calculations involved in producing pulses from such meters, it may be difcult to obtain repeatability. 7.7 Proving Meters Using Totalizers Meters can be equipped with electronic or mechanical totalizers that read directly in quantity units (cubic meters, gallons, barrels, pounds, etc.). When using mechanical and electronic totalizers for proving, the indication shall have a discrimination level (1 part in 10,000) as outlined in API MPMS Ch. 12.2. For example: a) the meter totalizer is incrementing in whole gallons (1 gallon) then the proof run shall be a minimum of 10,000 increments (10,000 gallons); b) the meter totalizer is incrementing in tenths of a gallon (0.1 gallon) then the proof run shall be a minimum of 10,000 increments (1000 gallons).