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API MPMS 4.9.1:2005(2015) pdf download

API MPMS 4.9.1:2005(2015) pdf download.Manual of Petroleum Measurement Standards Chapter 4-Proving Systems Section 9—Methods of Calibration for Displacement and Volumetric Tank Provers Part 1——Introduction to the Determination of the Volume of Displacement and Tank Provers.
The un,direciiottal prover sphere handling in rchange, the hi-directional power four-way salve, and all valves located between the calibrated section of the plover and the calibration unit. shall seal without any sisible internal or esternal leakage when in a closed position.
Ii is essential that the sphere handling interchange in a unidirectional prover, the four-way’ valve or the older ahernatise fosir.valve %ystcm% in a hi-directional prover, and any valve in a line hypassing the provcr. shall seal completely whcn closed, A prover sake, which does not shut oil flow completely, will cause %CfloUs cmv’s.
‘Tpcs of valves known as the ‘douhle-block-and-blced’ are used on provers where leak detection is essential. These valves are double seated with a space between the two seats that is connected to a small blced-valse. By opening this bleed sake the openitoe can make a positive check that the main valve is not leaking. Any leakage across either of the valve seats will reveal itself through the bleed. In some double-block-and-bleed systems, leakage is allowed to pass freely through the bleed to a location where it can be seen flowing; in other valves. thc bleed is connected to a pressure gauge so that rising or falling pressure is the indication of leakage.
The prover and all the associated piping involved during the calibration may contain relief, drain and vent valves. All of these valves normally dischajp, into the drainage system and can easily hide an unknown source of leakage. All of these valves shall have a means to visually verify that no leakage is occurring or they are to be isolated during each calibration ntis.
All valves located on the pniver system and in-line, up to the test nieasures, that are part of the calibration, and operating in an open position, shall be regularly inspected fur any signs of external leakage. Any leakage will cause an emr in the certified volume.
A temperature tneitsurenscnt is requited at the location where the liquid being displaced eSits the prover. Teniperalure measurements are usually tnade using certified or calibrated ttseicury’.in-glass thermometets or calibrated electronic temperature devices, In the case of a large diflerence in ientperattwc between the arithieni air and the calibration liquid, a thermometer stem correction may be required in accordance with API MF°MS Chapter 7. However, the need for stem coIyecti(wss is unlikely in the case of prover calibrations which are normally condacted near ambient conditions. The thermometer scale shall be in increments no greater than 0.2°F (0.1°C). and its accuracy shall be within 0.l°F(± 0.05°C).
A certified or calibrated thermometer shall be on-site with a certificate of calibration accuracy. The certificate of calibration shall be traceable in NIST or other appropriate national metrology institute. The certified thennometer shall be used to verify the accuracy of all the other themiometeni iworking thermometers) used in the calibration procedures. The certified or calibrated thermometer and the working thermometers must agree within ± 0.1°F (± 0.05°C). Alternatively, working thermometers that have been certified to have been verified at three points (e.g., high. mid and low’ range points i within one year and a day of the time of the prover calibration by a thermometer that has a calibration traceable to a national standani may also be used providing that all of them agree atnong themselves within ± 0.1°F (± 0.05°C).
Electronic temperature measurement devices may be used in the calibration if there is agreement between all the represented parties. If using electronic temperature measurement devices then the requirements laid out in API IJPMS Chaprer 7 “Temperature Measuremen(’, shall be followed. As pan of the requirement that the device be vciitied before each calibration, this verification shall he carried out against a calibrated or certified thermometer, accurate to ± 0.1 °‘F (0.05°C’ i
For watcrdruw calibrations, a pressure measurement is required downstream of the displacer. A connection to lit a pressure measuring device shall be provided between the water outlet from the prover and the pipe work poor to the water entering the test measures. Because of the very low flow rate when the water is flowing only through the solenoid valve, and the resulting minimal pressure drop at that time, it is acceptable to install the pressure mea.sia’ing device on the calibration unit.
Ptessure measurements are usually made using a calibrated dial type pressure gauge that is accurate and rearkibk to one pound per square inch (l-psig) increments, and shall have with it on-site a certificate of calibration accuracy. This certificate of caiibration shall be traceable to NIST or other apprupoate national metrulogy institute and shall he considered valid ii within one year and a day of the date of calibnitiun of the pressure gauge. Electronic pressure dcv ices or digital pressure gauges may be used in the calibration if there is agreement between all the represented parties. ‘Their readability and verifiable accuracy shall have exactly the sante requirements as those specified for dial type pressure gauges, including an on-site valid certificate of calibration accuracy.


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