1、BRITISH STANDARD BS ISOAutomatic steam trapsUDC621.186.6:001.4Incorporating corrigendumJuly 2009 Definition of technical terms6552:1980National forewordThis British Standard is the UK implementation of ISO 6552:1980, incorporating corrigendum July 2009. It supersedes BS 6023:1981 (dual numbered as B
2、S 6023:1981 / ISO 6552:1980), which is withdrawn.The UK participation in its preparation was entrusted by Technical Committee PSE/18, Industrial valves, steam traps, actuators and safety devices against excessive pressure, to Subcommittee PSE/18/1 Industrial valves, steam traps, actuators and safety
3、 devices against excessive pressure - Valves - Basic standards.A list of organizations represented on this subcommittee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct applicati
4、on.Compliance with a British Standard cannot confer immunity from legal obligations.BS ISO 6552:1980This British Standard, havingbeen prepared under thedirection of the MechanicalEngineering StandardsCommittee, was publishedunder the authority of theExecutive Board and comesinto effect on31 December
5、 1980 The British Standards Institution 2012. Published by BSI Standards Limited 2012.Amendments/corrigenda issued since publicationDate Comments 31 May 2012 Implementation of ISO corrigendum July 2009. The table in Subclause 2.3 has been amended, and thetitle has been aligned with the ISO title. Th
6、is corrigendum also renumbers BS 6023:1981 as BS ISO 6552:1980.ISBN 978 0 580 68660 310 IntroductionThe purpose of this International Standard is to establish precise definitions for technical terms and expressions which are commonly used to describe with a certain accuracy an automatic steam trap u
7、nder operating conditions.This International Standard has to be considered in conjunction with every other International Standard using these terms and expressions to describe the technical characteristics or performances of an automatic steam trap.1 Scope and field of applicationThis International
8、Standard gives the definitions of the major technical terms and expressions used to describe an automatic steam trap as far as dimension, pressure, temperature and flow rate are concerned, as well as their corresponding symbols and units.2 Definition of technical terms2.1 dimensionTerm Symbol Unit D
9、efinitionNominal size DN Numerical designation of size which is common to all components in a piping system other than components designated by outside diameters. It is a convenient round number for reference purposes and is only loosely related to manufacturing dimensions.In any case, the nominal s
10、ize DN cannot be subject to measurement and shall not be used for purposes of calculation.BS ISO 6552:198022.2 pressureTerm Symbol Unitsa DefinitionNominal pressure PN Numerical designation which is a convenient number for reference purposes.All equipment of the same nominal size (DN) designated by
11、the same PN number shall have the same mating dimensions.The permissible working pressure depends upon the material, the design and the working temperature, and shall be selected from the pressure/temperature rating tables in this International Standardb.Maximum allowable pressurePMA bar MPa Maximum
12、 pressure that the shell of the steam trap can withstand permanently at a given temperature.Maximum operating pressurePMO bar MPa Pressure for which a steam trap is rated by the manufacturer.This pressure is normally a function of the limitations related to the internal equipment of the steam trap.O
13、perating pressure PO bar MPa Pressure measured at the inlet of the steam trap under operating conditions.Operating back pressurePOB bar MPa Pressure measured at the outlet of the steam trap under operating conditions.Maximum operating back pressurePMOB bar MPa Maximum permissible pressure at the out
14、let of the steam trap allowing correct functioning.Operating differential pressure%P bar MPa Difference between the operating pressure and the operating back pressure.Maximum differential pressure%PMX bar MPa Maximum difference between operating pressure and operating back pressure.Minimum different
15、ial pressure%PMN bar MPa Minimum difference between operating pressure and operating back pressure.Test pressure PT bar MPa Pressure applied to the steam trap under test.Maximum test pressurePTMX bar MPa Maximum test pressure of the steam trap including its internal mechanism.a 1bar=0,1MPa.b See the
16、 note in the national foreword.BS ISO 6552:198032.3 temperature2.4 flow rateTerm Symbol Unit DefinitionBasic temperatureTB C Temperature taken into consideration in the determination of the dimensions of the steam trap.Maximum allowable temperatureTMA CMaximum operating temperatureTMO C Maximum temp
17、erature for which the operation of the steam trap is guaranteed.Operating temperatureTO C Temperature measured at the inlet of the steam trap under operating conditions.Term Symbol Unit DefinitionCold condensate capacityQC kg/h Maximum mass of condensate that the steam trap can discharge in1h at a g
18、iven differential pressure and a temperature of20C, the trap being fully open.Hot condensate capacityQH kg/h Maximum mass of condensate that a steam trap can discharge in1h at a given differential pressure and temperature.Maximum temperature to which the shell of the steam trap can be raised permane
19、ntly at a given pressure. BS ISO 6552:1980BSI is the independent national body responsible for preparing British Standards and other standards-related publications, information and services. It presents the UK view on standards in Europe and at the international level. BSI is incorporated by Royal C
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