API MPMS 5.3:2005 pdf download

API MPMS 5.3:2005 pdf download.Manual of Petroleum Measurement Standards Chapter 5- -Metering
Section 3- -Measurement of Liquid Hydrocarbons by Turbine Meters.
A.1 Scope
Et1èctie flow conditioning can often be obtained by using adequate lengths of snight pipe upstream and downstream of the meter Appendix A presents an empirical method for coinputing the length of upstream straight pipe required for arious installation configurations and operating conditions. Experience has shown that a nominal length of 20 diameters of meter- bore piping upstream of the meter and 5 diameters of meter- bore piping downstream of the meter pmside effectise cundinoning in many installations downstream of a simple elbow or tee. However, the required length of upstream piping should be enl,ed for each installation. using the method presented in this appendix. This technique does not predict the length of straight pipe required downstream of the meter A minimum of S diameten of meter-bore piping should be prosicled downstream of the meter tatless a dillerent length is supported by the manufacturer’s recommendations or tcst&
P2 Calculation of Upstream Flow- Conditioning Length
Hased on empirical data, the length of straight pipe required upstream of the meter can be calculated using F.quation A-I below:
B.1 Introduction
Appendix H supplements and clarifies the inftwmaiion on electrical installation requirements.
B.2 Generation of Electrical Signals
The principal types of devccs that produce clcctncal signals and are used with turhine meters are described in Sec. tions fl.2.l and B.2.2.
B.2.1 INDUCTANCE SYSTEM
In an inductance system, the rotating element of the turbine meter employs permanent magnets that may be embedded in the hub or the blade tips or attached to the rotor shaft or to a ring driven by the rotor. Regaidless of the design. magnetic flux from a moving magnet induces a voltage in a psckup coil that is located near the magnetic field.
B.2.2 VARIABLE RELUCTANCE SYSTEM
In a variable reluctance system, a pickup coil is located on the outside of the turbine meter housing such that the rotor blade tips or rotor rim passes near the tip of the pickup coil. A permanent magnet. located in the pickup coil. rwoduces a magnetic flux that estends into the housing. When rotation occurs, the peramagnctic blades cause a variation in the magneric flux that produces a voltage in the pickup coil. A rimmed rotor utilizes parainagnetic buttons or slots to cause the variation in the magnetic fluz
B.3 Summary
The inductance and variable reluctance syslens are tnIc generators, since both output frequency and voltage magnitude are proportional to rotor spccd The frequency of the output signal is directly proportional to rotor specd The inductance and variable reluctance systems are low power level devices because they generate only a few milliwatta of electrical power and the signal amplitude is proportional to rotor speed,
This output may be locally aniplilied, and in some instances shaped. at the turbine meter. The amplifier output may then be considered a high•lesel output, Ideally, devices that have a high power level are less susceptible to noise problems because of the increased signal-to-noise ratio.