1、Process Measurement API RECOMMENDED PRACTICE 551 SECOND EDITION,FEBRUARY 2016Special NotesAPI publications necessarily address problems of a general nature.With respect to particular circumstances,local,state,and federal laws and regulations should be reviewed.Neither API nor any of APIs employees,s
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13、the Director of Standards,American Petroleum Institute,1220 L Street,NW,Washington,DC 20005.Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director.Generally,API standards are reviewed and revised,reaffirmed,or withd
14、rawn at least every five years.A one-time extension of up to two years may be added to this review cycle.Status of the publication can be ascertained from the API Standards Department,telephone(202)682-8000.A catalog of API publications and materials is published annually by API,1220 L Street,NW,Was
15、hington,DC 20005.Suggested revisions are invited and should be submitted to the Standards Department,API,1220 L Street,NW,Washington,DC 20005,standardsapi.org.iiiContentsPage1Scope.12Normative References .13General.73.1Introduction.73.2Measurement Terminology.73.3Instrument Range Selection.83.4Instr
16、ument Selection.103.5Mechanical Integrity.123.6Metallurgy and Soft Goods Selection.123.7Signal Transmission and Communications.173.8Power,Grounding,and Isolation.193.9Local Indicators.203.10 Tagging and Nameplates.213.11 Configuration and Configuration Management.223.12 Documentation .224Temperature.224.1Introduction.224.2Thermowells.234.3Thermocouples.304.4Resistance Temperature Devices.364.5Thermistors.394.6Distributed Temperature Sensing.404.7Radiation Pyrometers.414.8Temperature Element Wiri
