1、Manual of PetroleumMeasurement StandardsChapter 5MeteringSection 5Fidelity and Security of Flow Measurement Pulsed-data Transmission SystemsSECOND EDITION, AUGUST 2005REAFFIRMED, AUGUST 2015Manual of PetroleumMeasurement StandardsChapter 5MeteringSection 5Fidelity and Security of Flow Measurement Pu
2、lsed-data Transmission SystemsMeasurement CoordinationSECONT EDITION, AUGUST 2005REAFFIRMED, AUGUST 2015SPECIAL NOTESAPI publications necessarily address problems of a general nature. With respect to partic-ular circumstances, local, state, and federal laws and regulations should be reviewed.API is
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14、REWORDChapter 5 of the API Manual of Petroleum Measurement Standards (API MPMS) provides recommendations, based on best industry practice, for the custody transfer metering of liquid hydrocarbons. The various sections of this Chapter are intended to be used in conjunction with API MPMS Chapter 6 to
15、provide design criteria for custody transfer metering encoun-tered in most aircraft, marine, pipeline, and terminal applications. The information contained in this chapter may also be applied to non-custody transfer metering.The chapter deals with the principal types of meters currently in use: disp
16、lacement meters, turbine meters and Coriolis meters. If other types of meters gain wide acceptance for the mea-surement of liquid hydrocarbon custody transfers, they will be included in subsequent sec-tions of this chapter.Suggested revisions to this publication are invited and should be submitted t
17、o Measure-ment Coordination, Exploration and Production Department, American Petroleum Institute, 1220 L Street, N.W., Washington, D. C. 20005.API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reli-ability of the data con
18、tained in them; however, the Institute makes no representation, war-ranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation wit
19、h which this publication may conflict.Suggested revisions are invited and should be submitted to API, Standards department, 1220 L Street, NW, Washington, DC 20005.iiiCONTENTSPage5.5.1 INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、15.5.2 SCOPE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15.5.3 FIELD OF APPLICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15.5.4 REFERENCED PUBLICATIONS. . . . . . . . . . .
21、. . . . . . . . . . . . . . . . . . . . . . . . . . . .15.5.5 DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15.5.6 LEVELS OF SECURITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
22、.5.6.1 Level E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15.5.6.2 Level D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25.5.6.3 Level C . . . . . . . . . . . . . . .
23、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25.5.6.4 Level B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25.5.6.5 Level A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、 . . . . . . . . . . . . . . . . . . .25.5.7 SYSTEM DESIGN CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25.5.7.1 General Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25.5.7.2 Totalizers. . . . . . . . . . . . .
25、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35.5.7.3 Typical Causes of Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35.5.7.4 Signal Pre-Amplifiers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26、. . . . . . . . . . .35.5.7.5 Standby Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35.5.7.6 Test Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35.5.7.7 General Precautions . . . . . . .
27、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35.5.8 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35.5.8.1 Signal Amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28、 . . . . . . . . . . .35.5.8.2 Signal-To-Noise Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35.5.8.3 Commissioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45.5.9 INSPECTION AND MAINTENANCE. . .
29、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45.5.9.1 Need for Inspection and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45.5.9.2 Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5F
30、igures1 Typical Function Arrangement for a Level E Pulsing Security System . . . . . . . . . .72 Typical Function Arrangement for a Level D Pulsing Security System . . . . . . . . . .73 Typical Function Arrangement for a Level C Pulsing Security System . . . . . . . . . .84 Typical Function Arrangem
31、ent for a Level B Pulsing Security System . . . . . . . . . .85 Typical Function Arrangement for a Level A Pulsing Security System . . . . . . . . . .9v1Chapter 5MeteringSection 5Fidelity and Security of Flow MeasurementPulsed-Data Transmission Systems5.5.1 IntroductionThe purpose of this publicatio
32、n is to serve as a guide for the selection, operation, and maintenance of various types of pulsed-data, cabled transmission systems for fluid metering systems to provide the desired level of fidelity and security of transmitted flow pulse data. This publication does not endorse or advocate the prefe
33、rential use of any specific type of equipment or systems, nor is it intended to restrict future development of such equipment.5.5.2 ScopeThe recommendations set forth in this publication are con-cerned only with the fidelity and security of pulsed-data, cabled transmission systems between a flow met
34、er or flow meter transducer and a remote totalizer.5.5.3 Field of ApplicationIn order to achieve different levels of security that can be applied to transmission systems, criteria and recommenda-tions for the design, installation, use, and maintenance of the relevant equipment are described in this
35、publication. The lev-els of security are designated E to A from the lowest to the highest order of security, respectively. Chapter 5 Section 5 does not define which levels of security are to be used for a particular system application.5.5.4 Referenced PublicationsThe current editions of the followin
36、g API MPMS Stan-dards contain information applicable to this chapter:Chapter 1 “Vocabulary”Chapter 21.2 “Electronic Flow Measurement”NFPA1493 Intrinsically Safe Apparatus in Division 1 Hazardous LocationsISA2RP 12.6 Installation of Intrinsically Safe Instrument Systems in Class 1 Hazardous Locations
37、5.5.5 DefinitionsSee API MPMS Chapter 1, “Vocabulary,” for additional definitions.5.5.5.1 fidelity: is defined as the exactitude with which the primary indication reproduces the inherent precision of the measurement.5.5.5.2 methods of comparision (as used in Levels A through D): is the determination
38、 of the fidelity of primary indication by use of a redundant, alternate, or secondary source to verify the desired level of security.5.5.5.3 noise: is unwanted signals that may affect fidelity and which occur for periods exceeding 0.2 seconds.5.5.5.4 scaler: is an electronic device that accepts flow
39、 pulses representing arbitrary volume or mass increments and outputs flow pulses scaled to represent more useful volume or mass increments, 1 pulse per barrel for example. 5.5.5.5 transients: are disturbances having a duration of 0.2 seconds or less.5.5.6 Levels of SecurityFive levels of security pr
40、otection are identified and desig-nated, of which Level E represents the minimum acceptable level. Typical examples of these five levels are shown dia-grammatically in Figures 1 through 5. A metering system may comprise sections having the same or different levels of security protection, where the o
41、utputs are used for different purposes. Figures 1 through 5 show typical functional arrangements of modules required to achieve the specified levels of security. These function modules may be housed separately or in combination.In the examples, emphasis has been placed on the trans-mission system be
42、cause this is considered the most vulnera-ble area of the whole. Fidelity and security for scaler and totalizer are not illustrated and are considered to be accept-able to Level E for the majority of applications. It may, how-ever, be considered necessary in some circumstances to duplicate the scale
43、r and/or totalizer section.5.5.6.1 LEVEL EError reduction at Level E is achieved solely by correctly installed apparatus of good quality. This is a straightforward totalizer system. Figure 1 illustrates a simple system with no built-in provisions for error monitoring. Only good quality 1National Fir
44、e Protection Association, 1 Batterymarch Park, Quincy, Massachusetts, 02169. www.nfpa.org.2The Instrumentation, Systems, and Automation Society, 67 Alex-ander Drive, Research Triangle Park, North Carolina, 27709. www.isa.org.2CHAPTER 5METERINGcomponents and subunits, correctly installed, will lead t
45、o con-fidence in the security of the system. The use of a preampli-fier transmitter to drive the transmission line is considered beneficial for the majority of applications, as is the provision of signal conditioning. The system, though simple, does not differ in hardware quality from more secure sy
46、stems that use the same elements.5.5.6.2 LEVEL DA Level D system consists of manual error monitoring at specified intervals by methods of comparison. This level of security is intended to give protection against functional errors and failures and is a method of verification by manual action. The rea
47、dout can be visually checked against an inde-pendent totalizing system.Figure 2 illustrates a simple system with means of making a periodic manual assessment of security. The secondary readout may be permanent or temporary, local or remote. Manual comparison made during a periodic check will moni-to
48、r the integrity of the transmission and totalizer elements. It may be less convenient than provisions of Level C, as the sys-tem may have to be stopped for readings to be taken. Overall security is mainly inferred from the performance during the error monitoring period5.5.6.3 LEVEL CA Level C system
49、 consists of automatic error monitoring and error indication at specified intervals by methods of com-parison. This level of security is intended to give protection against functional errors and failures and may be achieved by design methods. The time intervals for error monitoring may be subject to revision in the light of experience gained. Figure 3 illustrates a dual transmission system with a dual pulse comparator of simple design. If the pulses delivered become numerically out of a step, warning will be given by the com-parator (differential counter). Level C security will be def
