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豆丁网:/kmust1british standardrefrigerating systems and heat pumps safety switching devices for limiting the pressure requirements and teststhe european standard en 12263:1998 has the status of abritish standardics 27.080; 27.200| bs en12263:1999|no copying without bsi permission except as permitted by copyright lawbs en 12263:1999national forewordthis british standard is the english language version of en 12263:1998.the uk participation in its preparation was entrusted to technical committeerhe/18, refrigeration safety, which has the responsibility to: aid enquirers to understand the text; present to the responsible european committee any enquiries on the interpretation, or proposals for change, and keep the uk interests informed; monitor related international and european developments and promulgate them in the uk.a list of organizations represented on this committee can be obtained on request to its secretary.cross-referencesthe british standards which implement international or european publications referred to in this document may be found in the bsi standards catalogue under the section entitled international standards correspondence index, or by using thefind facility of the bsi standards electronic catalogue.a british standard does not purport to include all the necessary provisions of a contract. users of british standards are responsible for their correct application.compliance with a british standard does not of itself confer immunity from legal obligations.summary of pagesthis document comprises a front cover, an inside front cover, the en title page, pages 2 to 9 and a back cover.amd. no.datetext affectedthis british standard, having been prepared under the direction of the engineeringsector committee, was published under the authority of the standards committee and comes into effect on 15 april 1999bsi 04-1999isbn 0 580 29284 3amendments issued since publicationeuropean standarden 12263norme europe enneeuropa ische normnovember 1998ics 27.080; 27.200descriptors: cooling systems, refrigerating, heat pumps, safety devices, pressure limiters, specifications, tests, testing conditions, adjustment, instructions, markingenglish versionrefrigerating systems and heat pumps safety switching devices for limiting the pressure requirements and testssyste mes de re frige ration et pompes a chaleur dispositifs-interrupteurs de se curite limitant la pression exigences et essaiska lteanlagen und wa rmepumpen sicherheitsschalteinrichtungen zurdruckbegrenzung anforderungen und pru fungenthis european standard was approved by cen on 4 march 1998.cen members are bound to comply with the cen/cenelec internal regulations which stipulate the conditions for giving this european standard the status of a national standard without any alteration. up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the central secretariat or to any cen member.this european standard exists in three official versions (english, french, german). a version in any other language made by translation under the responsibility of a cen member into its own language and notified to the central secretariat has the same status as the official versions.cen members are the national standards bodies of austria, belgium, czech republic, denmark, finland, france, germany, greece, iceland, ireland, italy, luxembourg, netherlands, norway, portugal, spain, sweden, switzerland and united kingdom.ceneuropean committee for standardization comite europe en de normalisation europa isches komitee fu r normungcentral secretariat: rue de stassart 36, b-1050 brussels1998 cen all rights of exploitation in any form and by any means reserved worldwide for cen nationalmembers.ref. no. en 12263:1998 epage 5en 12263:1998bsi 04-1999forewordthis european standard has been prepared by technical committee cen/tc 182, refrigerating systems, safety and environmental requirements, thecontentspagesecretariat of which is held by din.this european standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by may 1999, and conflicting national standards shall be withdrawn atthe latest by may 1999.this european standard has been prepared under a mandate given to cen by the european commission and the european free trade association, and supports essential requirements of the eudirective 97/23/ec.for relationship with eu directive(s), see informative annex za, which is an integral part of this standard.according to the cen/cenelec internal regulations, the national standards organizations of the following countries are bound to implement this european standard: austria, belgium, czech republic, denmark, finland, france, germany, greece, iceland, ireland, italy, luxembourg, netherlands, norway, portugal, spain, sweden, switzerland and the united kingdom.foreword 21scope 32normative references 33definitions 34requirements and tests 45installation and operating instructions 76marking 7annex a (informative) symbols and equivalentterms in english, french and german 8annex za (informative) clauses of this europeanstandard addressing essential requirements orother provisions of ec directives 91 scope1.1 this european standard establishes the requirements and tests applied to safety switching devices for limiting the pressure (hereafter called devices) to ensure that the maximum or minimum pressure, which is caused by a pressure generator in refrigerating systems and/or heat pumps, is maintained within the limits of the refrigerating system and/or heat pump. these devices are of special construction andare equipped with mechanically operated output contacts.note devices may be wired directly into the control circuit of the compressor or may be connected through a relay or microprocessor/computer.transducers/analogue devices are not covered by this standard.if more stringent specifications for special applications are necessary, these should be agreed between the customer and the manufacturer of the devices.1.2 different safety and control functions can be combined in one device.1.3 this standard does not apply to devices used for control purposes.2 normative referencesthis european standard incorporates, by dated or undated reference, provisions from other publications. these normative references are cited at the appropriate places in the text and the publications are listed hereafter. for dated references, subsequent amendments to or revisions of any of these publications apply to this european standard onlywhen incorporated in it by amendment or revision. for undated references, the latest edition of the publication referred to applies.en 60529, degrees of protection provided by enclosures(ip code).(iec 529:1989)en 60730-1:1995, automatic electrical controls for household and similar use part 1: general requirements.(iec 730-1:1993, modified)en 60730-2-6:1995, automatic electrical controls for household and similar use part 2: particular requirements for automatic electrical pressure sensing controls including mechanical requirements.(iec 730-2-6:1991, modified)en 60947-5-1:1991, low-voltage switchgear and controlgear part 5: control circuit devices and switching elements section 1: electromechanical control circuit devices.(iec 947-5-1:1990)en 60068-2-6, environmental testing part 2: tests test fc: vibration (sinusoidal).(iec 68-2-6:1995 + corrigendum 1995)3 definitionsfor the purposes of this european standard the following definitions apply.note symbols and equivalent terms are specified in annex a.3.1safety switching device for limiting pressurepressure-actuated device that is designed to stop the operation of the pressure generatornote these devices can be designed to limit the high pressure (h) or to limit the low pressure (l) to one predetermined value during abnormal operating conditions.3.1.1pressure limiterdevice which automatically resetsnote 1 it is called psh for high-pressure protection and psl for low-pressure protection (see annex a).note 2 the devices automatically cut out when a set pressure limit is exceeded, and they automatically cut in again.3.1.2pressure cut-outdevice which is manually reset without the aid of a toolnote 1 it is called pzh for high-pressure protection and pzl for low-pressure protection (see annex a).note 2 the devices automatically cut out when a set pressure limit is exceeded and are manually reset without the aid of a tool.3.1.3safety pressure cut-outdevice which is manually reset only with the aid of a toolnote 1 it is called pzhh for high-pressure protection and pzllfor low-pressure protection (see annex a).note 2 the devices automatically cut out when a set pressure limit is exceeded and are manually reset only with the aid of a tool.3.2cut-out pressurepressure at which the contacts in the control circuit open to stop the pressure generatornote this will occur with a rising pressure for high-pressure protection and a falling pressure for low-pressure protection.3.3cut-in pressurepressure at which the contacts in the control circuit close to start the pressure generatornote this will occur with a falling pressure for high-pressure protection and a rising pressure for low-pressure protection, as well as by manual reset.3.4setting rangepressure range within which the cut-out pressure can be set3.5upper switching pressurepressure at which the device switches during pressure rise (cut-out or cut-in)3.6lower switching pressurepressure at which the device switches during pressure fall (cut-out or cut-in)3.7 differentialpressure difference between the upper and lower switching pressurenote for devices with manual reset, the lower or upper switching pressure will be that at which the device is capable of being reset.3.8 driftpermanent alterations which can occur when a device has been tested under the conditions specified in this standard3.9 deviationtemporary alterations which disappear when the device is no longer subjected to the test conditions3.10maximum declared pressure, pmaxpressure, declared by the manufacturer, to which the component or device may be subjected without reducing its performance3.11allowable temperature rangerange between the maximum and minimum ambient temperature within which the performance of the device is not reduced4 requirements and tests4.1 general requirements and test conditions devices shall be so designed and constructed that in normal use they function so as to cause no danger topersons and surroundings, even in the event of anyforeseeable misuse which may occur during operation.unless otherwise specified, all tests shall be carried out at an ambient temperature of 20 8c to 25 8c. for accuracy of measurement, the pressure applied to the device shall not change at a rate of morethan 10 bar/min.three samples of each type shall undergo and pass all the described tests.however, only two are used for the burst test and the third for the test of fail-safe function of the measuring element.4.2 mechanical requirements4.2.1 design and endurancethe materials used in the construction of the devices shall be able to withstand the thermal, mechanical and chemical stresses occurring in the range of application for which the devices are provided. corrosive effects, in particular, shall not affect the function of the devices.the design of the device shall ensure a snap-action characteristic of the contact system.devices with automatic reset shall have a mechanical life of at least 5 000 switching operations.devices with manual reset shall withstand at least 500 reset operations.in addition, the devices shall withstand atleast 50 000 pressure cycles without switching.4.2.2 devices with manual resetthe manual reset shall be designed trip-free according to 2.3.15 of en 60730-1:1995. the reset mechanism shall be independent of other setting mechanisms.4.3 electrical requirements4.3.1 safetyfor electrical safety, the following clausesof en 60730-2-6:1995 are applicable and the manufacturer shall declare compliance thereto: clause 8: touch protection against electric shock; clause 9: provision for protective earthing; clause 12: moisture and dust resistance; clause 13: electrical strength and insulation resistance; clause 14: heating; clause 17.2: electrical conditions for the tests; clause 19: threaded parts and connections; clause 20: creepage distances, clearances and distances through insulation; clause 21: resistance to heat, fire and tracking.4.3.2 fuse protectionthe required fuse protection against short circuit shall be indicated by the manufacturer in accordancewith 8.3.4 of en 60947-5-1:1991.4.4 setting, range and accuracy4.4.1 set-point adjustmentthe cut-out pressure shall be shown on the device, either by marking of a fixed setting or by a scale indication on adjustable devices.on adjustable devices, changes of setting shall only be possible by means of a tool.it shall be possible to protect the devices against alteration of settings by unauthorized persons.4.4.2 setting rangehigh-pressure devices shall be protected against excessive set-point adjustment above the maximum set-point range. this protection shall not allow acut-out pressure higher than the maximum range value +15 % or +3 bar, whichever is the greater.4.4.3 accuracy of settingthe accurate setting of the upper and lower switching pressures shall be established by means of a suitable pressure gauge, because the setting scales show only approximate values.devices with fixed factory setting for high-pressure protection shall have a cut-out pressure kept within a deviation of 0 bar to 20,25 bar or 0 % to 28 % of the specified settings, whichever is the greater.devices with fixed factory setting for low-pressure protection shall have a cut-out pressure kept within a deviation of 0 bar to +0,25 bar or 0 % to +8 % of the specified settings, whichever is the greater.4.5 tests: pressure overload, ambient temperature, mechanical endurance4.5.1 preparationadjustable devices shall be set to mid-range and mid-differential.devices with fixed settings shall be supplied having mid-range and mid-differential settings.a reference value for upper and lower switching pressures is to be measured and shall be applied in the tests required by the following subclauses of .2 drift and deviation of cut-outdrift and deviation of cut-out from the reference value shall not exceed the following: for devices for high-pressure protection:reference value +0,25 bar or +5 %, whichever is the greater; for devices for low-pressure protection:reference value 20,25 bar or 25 %, whichever is the greater.drift in the safe direction shall not exceed twice the above-mentioned tolerances.4.5.3 pressure overloadthe devices are exposed to 20,95 bar or lower(vacuum) for 1 min.50 pressure variations between 0 bar and 1,1 times the maximum declared pressure are then applied and the cut-out pressure drift is determined by comparison with the reference value.4.5.4 ambient temperaturethe devices are subjected to a temperature of 220 8c1k until they have reached this temperature.subsequently the devices are subjected to +55 8c1k until they have reached this temperature.at both temperatures the cut-out deviation is determined by comparison with the reference value.4.5.5 mechanical endurancea) pressure limiters are subjected to 5 000 switching operations with the following pressure variation:1) upper pressure level: reference value +10 %;2) lower pressure level: reference value 210 %.b) pressure cut-outs and safety pressure cut-outs are subjected to 500 reset operations with the following pressure variation: devices for high-pressure protection:1) upper pressure level: reference value +10 %;2) lower pressure level: reset mechanism is initiated when the pressure is 10 % below the pressure at which reset is possible; devices for low-pressure protection:1) lower pressure level: reference value 210 %;2) upper pressure level: reset mechanism is initiated when the pressure is 10 % above the pressure at which reset is possible.c) the devices are subjected to 50 000 pressure cycles at 1 000 cycles per hour as follows: devices for high-pressure protection:1) value for upper pressure level: 1 bar below the
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