API MPMS 5.6:2022 pdf download
API MPMS 5.6:2022 pdf download.Manual of Petroleum Measurement Standards Chapter 5.6.
Higher fluid velocities, when coupled with abrasive particles in the stream, can cause flow tube erosion and measurement error. The user should consult the manufacturer to ensure that the flow tube material is compatible with operating conditions and fluid properties, including corrosiveness or abrasiveness characteristics.
5.1.2 Accuracy
Sensors have different accuracy specifications and sensitivities with regard to changes in ambient and operating conditions. Consult the manufacturer for the performance envelope describing error limits throughout these conditions and consider the limits with respect to the system requirements.
To address the effects of process pressure and temperature on the accuracy of the measurement of mass, density, and the corresponding determination of volume:
— Temperature effect compensation for the flow tube(s) stiffness shall be integral to the meter and performed real time in the meter.
NOTE This temperature measurement is typically flow tube skin temperature and might not be sufficient for CTL calculations. See API MPMS Ch. 7141.
— Pressure effect compensation for flow tube stiffness is recommended for all applications, but is required when the effect is biasing quantity determination by more than 0.05 %. Generalized equations for evaluation of the effect are provided in Annex D.
NOTE This pressure effect compensation is not the correction for compressibility of liquid (CPL).
— Pressure effect on flow tube stiffness can also affect density determination and its use within volume calculations (e.g., CTL, CPL, CTPL). Refer to API MPMS Ch. 9[61•
Real-time pressure compensation can be accomplished by:
— activating the pressure effect compensation mode in the transmitter (if available) and using a live pressure input (analog or digital communication) to continuously adjust for pressure change. Pressure values should be shared between the transmitter and tertiary device for audit purposes; or
— activating the pressure effect compensation mode in the transmitter and using a live pressure measurement integral to the sensor. Pressure values should be shared between the transmitter and tertiary device for audit purposes. This integral pressure value may not be suitable for other calculations requiring a pressure value; or
— calculating the pressure compensation in a tertiary device. See Annex D for details.
In lieu of real-time pressure compensation:
— prove the meter close enough to the average operating pressure to satisfy Equation (D.2) in Annex D; or
— correct the quantity external to the transmitter in an off-site measurement system (see Annex D and Annex E).
Any change in pressure compensation values or implementation of pressure compensation requires proving (see 7.2.7).
In both mass and volume measurement applications, this standard requires documentation of flow tube pressure effect compensation in accordance with PECI status in Annex D.
5.1.3 Flow Tube Pressure Rating
Flow tube(s) and end connections shall meet the pressure code requirement for the service. The external housing around the flow tube(s) is designed to protect the sensor electronics and typically not designed to meet the same pressure ratings as the flow tube(s).
5.1.4 Documentation
Meter manufacturers provide calibration certificates. Other documentation for the meter, such as electrical area classification certification, pressure ratings on the flow tube(s), pressure containment ability of the outer flow tube case, hydrostatic test report, and material test reports can be provided.
5.1.5 Bidirectional Flow
If bidirectional flow is required, ensure that the transmitter and the flow computer are both compatible with bidirectional flow. If the meter is used to measure bidirectional flow, a meter factor shall be developed for each flow direction.
si Pressure Containment and Relief
Optional sensor features can be provided by the manufacturer to reduce the effect of flow tube failure, Items to consider:
— sensor housings constructed as a pressure-containing vessel, designed to contain fluid under pressure to a specified pressure limit;
— rupture disks, pressure relief valves and drains, or vents on the sensor housing, designed to relieve pressure or allow fluid release from inside the sensor housing.
