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API MPMS 4.2:2003(2015) pdf download

API MPMS 4.2:2003(2015) pdf download.Manual of Petroleum Measurement Standards Chapter 4-Proving Systems Section 2—Displacement Provers.
This would require six scale and temperature readings. six calculations, and would take a considerable amount of time to till and drain the six test measures.
If the prover volumc would be adjusted up to 100 gallons between the switches. thc calibration would require only one 100 gallon test measure. This will reduce the calibration time and uncertainty.
Other things to consider that may increase the volume required include:
a. The variance of the actual K factor from the manufacturer’s typical published K factor for turbine meters may result in less than 10,000 pulses.
b. For small displacement meters. generally less than 4 in.. which use mechanical gearing in their pulse generation train, the volume may need to be increased to the next whole unit of volume per revolution of the meter to avoid the cyclical effects of the clutch calibrator. For example. 5 gallon incremeats on 5 — I gallon-geared meters.
4.3.4 Displacer Velocities
Some practical limit to the maximum velocity of a displacer must be established to lres’ent damage to the displacer and the detectors. Nevertheless, the developing state of the art advises against setting a firm limit to displacer velocity as a criterion for design. Demonstrated results are better to use as a criterion. The results are manifested in the repeatability and reproducibility of MFs using the prover in question. Other considerations include consistency of the prover diameter and prover surfaces along with the friction between the prover and displacer’s scaling surfaces. MaxImum Displacer Velocities
For sphere displacers, most operators and designers agree that 10 ft/sec. is a typical design specification for unidirectional provers, whereas velocities tip to 5 ftsec. are typical in bidirectional provers.
For piston displacers. a maximum velocity of 3ftlsec. — 5 ftsec. is recommended, depending on the design.
higher velocities may be possible if the design incorporates a means of limiting mechanical and hydraulic shock as the dip lacer completes its pass. Minimum Displacer Velocities
Minimum displacer velocity must also be considered. especially for proving meters in a liquid that has little or no lubricating ability, such as gasoline that contains high proportions of aromatics or liquefied petroleum gas. The displacer should move at a unitbrm velocity between detectors. Allow velocities when the lubricating ability is poor. the sealing friction is high, andor the prover surface is rough. the displacer may chatter.
Prover prerun is the length of pipe required for the dis-placer to travel from its holding or resting location to the firstdetector. The minimum prerun length must allow for suffi-cient time to bring the displacer up to maximum stable veloc-ity before reaching the calibrated section of the prover. It alsomust provide sufficient time for the interchange or flowreversing valve (e.g., 4-way valve) to cycle and seal.
The valve and interchange manufacturer should be con-sulted to establish minimum travel and seal times, and maxi-mum allowable velocity. Consideration should be given toinstallation of a valve or interchange seal detector so that theproving controls can determine that a seal has been estab-lished before the displacer reaches the first detector of the cal-ibrated section.
Methods used to shorten this prerun, such as faster opera-tion of the valve or delay of the displacer launching, requirethat caution be exercised in the design so that hydraulic shockor additional undesired pressure drop is not introduced. Ifmore than one flow-directing valve is used,they should besequenced to prevent shock.
The prerun length is calculated as follows:
5 lnstallation
All components of the prover installation, including elec-trical, piping,valves, and manifolds, shall be in accordancewith applicable codes. Once the prover is in service,itbecomes a part of the pressure piping system.
The proving section and related components shall have suit-able hangers and supports prescribed by applicable codes andgood engineering principles. When proving systems aredesigned and installed, precautions should be taken to copewith expansion,contraction,vibration,pressure surges,andother conditions that may affect piping and related equipment.Adequate access to all equipment and parts of the proversystem for maintenance purposes,meter proving activitiesand prover calibration requirements shall be provided. Thismay include walkways,space for field standard installation,and truck access.
Valving to isolate the prover unit from line pressure whenit is not on strean (e.g.,during maintenance or removal of thedisplacer) must be provided.


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