EN 16129:2013

Pressure regulators, automatic change-over devices, having a maximum regulated pressure of 4 bar, with a maximum capacity of 150 kg/h, associated safety devices and adaptors for butane, propane, and their mixtures

This European Standard defines the constructional and operational characteristics, the safety requirements, test methods and the marking of regulators and automatic change-over devices having a maximum regulated pressure of 4 bar, with a maximum capacity of 150 kg/h, for use with butane, propane and their mixtures in the vapour phase.
This European Standard also applies to the safety devices which are included within regulating devices covered by this standard. The characteristics of these safety devices are given in Annexes A and B.
This European Standard also includes the requirements for:
-   adaptors for connecting to self closing valves;
-   auxiliary safety devices.
For the purpose of this European Standard:
-   regulators and automatic change-over devices are referred to as "regulating devices";
-   regulators, automatic change-over devices and adaptors are referred to as "devices".
The requirements apply to devices used in locations where the temperature likely to be reached during use is between -20 °C and +50 °C. Additional requirements for devices to be used at temperatures below –20 °C are given in Annex C.
Additional requirements for regulating devices intended to be used in caravans, motor caravans and freshwater boats are given in Annex D.
Additional requirements for regulating devices intended to be used in seawater boats are given in Annex M.
For specific use in caravans motor caravans and boats (freshwater and seawater), the automatic change over device function may also be carried out by an assembly of regulators, forming an "automatic change over device system" as defined in 3.1.9.
For installation rules of devices and their possible associated safety devices, reference should be made to national regulations in force in the member countries.
All connections and the countries in which they are used are given in Annexes G and H.
This European Standard defines only specific connections which are not defined in other standards (e.g. EN 15202 for cylinder valve connections).

Druckregelgeräte, automatische Umschaltanlagen mit einem höchstem Ausgangsdruck bis einschließlich 4 bar und einem maximalen Durchfluss von 150 kg/h sowie die dazugehörigen Sicherheitseinrichtungen und Übergangsstücke für Butan, Propan und deren Gemische

Diese Europäische Norm definiert die Bau- und Betriebseigenschaften, die Sicherheitsanforderungen und die Prüfverfahren und die Kennzeichnung von Druckregelgeräten und automatischen Umschaltventilen mit einem höchsten Ausgangsdruck bis einschließlich 4 bar und einem Durchfluss bis einschließlich 150 kg/h für Butan, Propan oder deren Gemische in der Dampfphase.
Diese Europäische Norm gilt ebenso für die in Druckregeleinrichtungen nach dieser Norm integrierte Sicherheitseinrichtungen. Die Eigenschaften dieser Sicherheitseinrichtungen sind in den Anhängen A und B beschrieben.
Diese Norm beinhaltet auch Anforderungen an:
Adapter für den Anschluss an selbstschließende Ventile;
zusätzliche Sicherheitseinrichtungen.
In Sinne dieser Norm werden
 Druckregelgeräte und automatische Umschalteinrichtungen als „Druckregeleinrichtung“;
 Druckregelgeräte, automatische Umschalteinrichtungen und Adapter als „Einrichtungen“
bezeichnet.
Die Anforderungen gelten generell für Einrichtungen, die in Gegenden benutzt werden, in denen die Temperatur bei der Benutzung zwischen −20 °C und +50 °C beträgt. Zusätzliche Anforderungen für Einrichtungen, die bei Temperaturen unterhalb −20 °C benutzt werden, sind in Anhang C definiert.
Zusätzliche Anforderungen an Druckregelgeräte, die dazu bestimmt sind, in Caravans, Motorcaravans und Süßwasserbooten benutzt zu werden, werden in Anhang D beschrieben.
Zusätzliche Anforderungen an Druckregelgeräte, die dazu bestimmt sind, in Seewasserbooten benutzt zu werden, werden in Anhang M beschrieben.
Für die spezielle Anwendung in Caravans; Motorcaravans und Booten (Süßwasser und Seewasser) kann die automatische Umschaltfunktion auch durch eine Kombination von Druckregelgeräten erfolgen, die ein System eines automatischen Umschaltventils bilden, das in 3.1.9 definiert ist.
Zu den Installationsvorschriften der Einrichtungen und deren möglichen zugehörigen Sicherheitseinrichtungen sollten Hinweise auf die geltenden nationalen Bestimmungen der Mitgliedsstaaten gegeben werden.
Alle Anschlüsse und die Länder, in denen diese verwendet werden, werden in den Anhängen G und H beschrieben.
Diese Europäische Norm beschreibt ausschließlich Verbindungen, die nicht in anderen Normen beschrieben werden (z. B. EN 15202 für Flaschenventilanschlüsse).

Détendeurs, inverseurs automatiques, ayant une pression maximum de détente de 4 bar, avec une capacité maximale de 150 kg/h, dispositifs de sécurité associés et adaptateurs pour butane, propane et leurs mélanges

La présente Norme européenne définit les caractéristiques de construction et de fonctionnement, les exigences de sécurité, les méthodes d’essai et le marquage des détendeurs et des inverseurs automatiques ayant une pression maximum de détente de 4 bar avec une capacité maximale de 150 kg/h, pour utilisation avec du butane, du propane et leurs mélanges en phase gazeuse.
La présente Norme européenne est également applicable aux dispositifs de sécurité qui sont susceptibles d’équiper les dispositifs de détente visés par la présente norme. Les caractéristiques de ces dispositifs de sécurité sont données dans les Annexes A et B.
La présente Norme européenne comprend également les exigences pour :
   les adaptateurs pour raccorder les valves automatiques ;
   les dispositifs de sécurité auxiliaires.
Pour les besoins de la présente Norme européenne :
   les détendeurs et les inverseurs automatiques sont appelés « dispositifs de détente » ;
   les détendeurs, inverseurs automatiques et adaptateurs sont appelés « dispositifs ».
Les exigences s’appliquent aux dispositifs utilisés dans les endroits où la température susceptible d’être atteinte en cours d’utilisation est comprise entre –20 °C et +50 °C. Les exigences supplémentaires pour les dispositifs utilisés à des températures inférieures à –20 °C sont données en Annexe C.
Les exigences supplémentaires pour les dispositifs de détente destinés à être utilisés dans les caravanes, les autocaravanes et les bateaux d’eau douce sont données en Annexe D.
Les exigences supplémentaires pour les dispositifs de détente destinés à être utilisés dans les bateaux d’eau de mer sont données en Annexe M.
Pour l’usage spécifique, dans les caravanes, autocaravanes et bateaux (d’eau douce et d’eau de mer), la fonction inverseur automatique peut également être assurée par un ensemble de détendeurs formant un « système d’inversion automatique » tel que défini en 3.1.9.
Pour les règles d’installation des dispositifs et des dispositifs de sécurité qui peuvent y être associés, il convient de consulter les réglementations nationales en vigueur dans les pays membres.
Tous les raccords et les pays où ils sont utilisés sont indiqués en Annexes G et H.
La présente Norme européenne ne définit que les raccords spécifiques qui ne sont pas définis dans d’autres normes (par ex. l’EN 15202 pour les raccords des robinets ou valves de bouteilles).

Regulatorji tlaka, samodejni preklopni ventili z največjim nastavljivim tlakom do vključno 4 bar, s pretokom do vključno 150 kg/h in s pripadajočimi varnostnimi napravami ter priključki za butan, propan in njune zmesi

Ta evropski standard določa konstrukcijske in obratovalne značilnosti, varnostne zahteve, preskusne metode ter označevanje regulatorjev in samodejnih preklopnih ventilov z največjim nastavljivim tlakom do vključno 4 barov, s pretokom do vključno 150 kg/h, za uporabo z butanom, propanom in njunimi zmesmi v plinastem stanju. Ta evropski standard se uporablja tudi za varnostne naprave, ki so vključene v okvir regulacijskih naprav iz tega standarda. Značilnosti teh varnostnih naprav so navedene v dodatkih A in B. Ta evropski standard zajema tudi zahteve za: – priključke za priključitev na samozaporne ventile; – pomožne varnostne naprave. V tem evropskem standardu: – se regulatorji in samodejni preklopni ventili imenujejo »regulacijske naprave«; – regulatorji, samodejni preklopni ventili in priključki pa »naprave«. Zahteve se uporabljajo za naprave na lokacijah, kjer bo temperatura med uporabo najverjetneje znašala od –20 °C do +50 °C. Dodatne zahteve za naprave, ki se uporabljajo pri temperaturah pod –20 °C, so navedene v dodatku C. Dodatne zahteve za regulacijske naprave, namenjene za uporabo v počitniških prikolicah, avtodomih in sladkovodnih čolnih, so navedene v dodatku D. Dodatne zahteve za regulacijske naprave, namenjene za uporabo v pomorskih čolnih, so navedene v dodatku M. Pri posebni uporabi v počitniških prikolicah, avtodomih in čolnih (sladkovodnih in pomorskih) lahko funkcijo samodejnih preklopnih ventilov opravlja tudi sestav regulatorjev, ki tvorijo »sistem samodejnih preklopnih ventilov«, opredeljen v točki 3.1.9. V zvezi s pravili za vgradnjo naprav in njihovih morebitnih povezanih varnostnih naprav je potrebno sklicevanje na nacionalne predpise, veljavne v državah članicah. Vsi priključki in države, v katerih se uporabljajo, so navedeni v dodatkih G in H. Ta evropski standard opredeljuje samo specifične priključke, ki niso opredeljeni v drugih standardih (npr. EN 15202 za priključke ventilov jeklenk).

General Information

• Status: Published
• Publication Date: 11-Jun-2013
• Withdrawal Date: 30-Dec-2015
• ICS: 23.060.40 - Pressure regulators
• Technical Committee: CEN/TC 181 - Dedicated liquified petroleum gas appliances
• Drafting Committee: CEN/TC 181/WG 3 - Small non-domestic space heaters
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 12-Jun-2013
• Due Date: 08-Nov-2012
• Completion Date: 12-Jun-2013
• Directive: 2009/142/EC - DIRECTIVE 2009/142/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 30 November 2009 relating to appliances burning gaseous fuels
• Directive: 90/396/EEC - Appliances burning gaseous fuels
• Mandate: M/BC/CEN/89/6 - Standardization request to CEN concerning appliances burning gaseous fuels
• Ref Project: SIST EN 16129:2014 - Pressure regulators, automatic change-over devices, having a maximum regulated pressure of 4 bar, with a maximum capacity of 150 kg/h, associated safety devices and adaptors for butane, propane, and their mixtures

Relations

• Replaces: EN 13786:2004+A1:2008 - Automatic change-over valves having a maximum outlet pressure of up to and including 4 bar with a capacity of up to and including 100 kg/h, and their associated safety devices for butane, propane or their mixtures
• Effective Date: 08-Jun-2022
• Replaces: EN 13785:2005+A1:2008 - Regulators with a capacity of up to and including 100 kg/h, having a maximum nominal outlet pressure of up to and including 4 bar, other than those covered by EN 12864 and their associated safety devices for butane, propane or their mixtures
• Effective Date: 19-Jun-2013
• Replaces: EN 12864:2001/A1:2003 - Low-pressure, non adjustable regulators having a maximum outlet pressure of less than or equal to 200 mbar, with a capacity of less than or equal to 4 kg/h, and their associated safety devices for butane, propane or their mixtures
• Effective Date: 19-Jun-2013
• Replaces: EN 12864:2001/A2:2005 - Low-pressure, non adjustable regulators having a maximum outlet pressure of less than or equal to 200 mbar, with a capacity of less than or equal to 4 kg/h, and their associated safety devices for butane, propane or their mixtures
• Effective Date: 19-Jun-2013
• Replaces: EN 12864:2001/A3:2009 - Low-pressure, non adjustable regulators having a maximum outlet pressure of less than or equal to 200 mbar, with a capacity of less than or equal to 4 kg/h, and their associated safety devices for butane, propane or their mixtures
• Effective Date: 19-Jun-2013
• Replaces: EN 12864:2001 - Low-pressure, non adjustable regulators having a maximum outlet pressure of less than or equal to 200 mbar, with a capacity of less than or equal to 4 kg/h, and their associated safety devices for butane, propane or their mixtures
• Effective Date: 22-Dec-2008
• Revised: prEN 16129 - Pressure regulators, automatic change-over devices, having a maximum regulated pressure of 4 bar, with a maximum capacity of 150 kg/h, associated safety devices and adaptors for butane, propane, and their mixtures
• Effective Date: 24-Jan-2024
• Revised: FprEN 16129 - Pressure regulators, automatic change-over devices, having a maximum regulated pressure of 4 bar, with a maximum capacity of 150 kg/h, associated safety devices and adaptors for butane, propane, and their mixtures
• Effective Date: 11-Jan-2017
• Revised: EN 13786:2004 - Automatic change-over valves having a maximum outlet pressure of up to and including 4 bar with a capacity of up to and including 100 kg/h, and their associated safety devices for butane, propane or their mixtures
• Effective Date: 22-Dec-2008
• Revised: EN 13785:2005 - Regulators with a capacity of up to and including 100 kg/h, having a maximum nominal outlet pressure of up to and including 4 bar, other than those covered by EN 12864 and their associated safety devices for butane, propane or their mixtures
• Effective Date: 22-Dec-2008

Overview

EN 16129:2013 is the European standard governing pressure regulators, automatic change‑over devices, associated safety devices and adaptors for use with butane, propane and their mixtures in the vapour phase. It applies to devices with a maximum regulated pressure of 4 bar and a maximum capacity of 150 kg/h. The standard defines constructional and operational characteristics, safety requirements, test methods, marking, packaging and user instructions.

Key topics and requirements

• Scope and definitions: Clarifies terminology (regulating devices, devices, change‑over systems) and applicable gases and operating conditions.
• Design and constructional characteristics: Requirements for materials, sub‑assemblies (pressure sensing, regulation, back‑pressure, connections), mechanical strength and resistance to impact, pressure and corrosion.
• Performance requirements: Supply and regulated pressure ranges, flow performance, change‑over pressures and limits for different device types (regulators, automatic change‑over devices, variable and fixed regulators).
• Safety devices: Includes requirements for integrated safety features (over‑pressure relief valves, OPSO/UPSO, excess flow valves, regulated outlet pressure limiters). Annexes A and B give detailed characteristics for certain safety devices.
• Environmental and special use conditions: Devices are covered for normal use between -20 °C and +50 °C; Annex C provides additional requirements for temperatures below -20 °C. Annex D covers caravans, motor caravans and freshwater boats; Annex M covers seawater boats.
• Tests and verification: Type test methods, test gas and conditions, mechanical endurance, soundness, flow/pressure plotting and equivalence formulas are specified.
• Marking, packaging and documentation: Mandatory marking details, packaging and required installation/use/maintenance instructions are defined.
• Connections and adaptors: Lists national connector types in Annexes G and H; standard defines only connections not covered by other standards (see EN 15202 for cylinder valve connections).

Practical applications and users

EN 16129:2013 is used by:

• Manufacturers of pressure regulators, change‑over devices, adaptors and integrated safety devices to design and certify compliant products.
• Test laboratories and certification bodies performing type testing and conformity assessment.
• System designers and installers in domestic, leisure (caravans, boats) and small commercial LPG systems to select compliant components.
• Regulators and procurement teams specifying safe, standardized gas pressure control equipment for supply and safety.
• Maritime and caravan equipment suppliers applying the annex requirements for freshwater and seawater use.

Related standards

• EN 15202 (cylinder valve connections) - referenced for connection definitions.
• National installation regulations - installation rules must follow member-country legislation.

Keywords: EN 16129:2013, pressure regulators, automatic change‑over devices, butane, propane, safety devices, adaptors, regulating devices, 4 bar, 150 kg/h, vapour phase.

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Druckregelgeräte, automatische Umschaltanlagen mit einem höchstem Ausgangsdruck bis einschließlich 4 bar und einem maximalen Durchfluss von 150 kg/h sowie die dazugehörigen Sicherheitseinrichtungen und Übergangsstücke für Butan, Propan und deren GemischeDétendeurs, inverseurs automatiques, ayant une pression maximum de détente de 4 bar, avec une capacité maximale de 100 kg/h, dispositifs de sécurité associés et adaptateurs pour butane, propane et leurs mélangesPressure regulators, automatic change-over devices, having a maximum regulated pressure of 4 bar, with a maximum capacity of 150 kg/h, associated safety devices and adaptors for butane, propane, and their mixtures23.060.40Pressure regulatorsICS:Ta slovenski standard je istoveten z:EN 16129:2013SIST EN 16129:2014en,fr,de01-januar-2014SIST EN 16129:2014SLOVENSKI
STANDARDSIST EN 12864:2002/A3:2009SIST EN 13785:2005+A1:2009SIST EN 13786:2004+A1:2009SIST EN 12864:2002SIST EN 12864:2002/A1:2004SIST EN 12864:2002/A2:20051DGRPHãþD

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16129
June 2013 ICS 23.060.40 Supersedes EN 12864:2001, EN 13785:2005+A1:2008, EN 13786:2004+A1:2008English Version
Pressure regulators, automatic change-over devices, having a maximum regulated pressure of 4 bar, with a maximum capacity of 150 kg/h, associated safety devices and adaptors for butane, propane, and their mixtures
Détendeurs, inverseurs automatiques, ayant une pression maximum de détente de 4 bar, avec une capacité maximale de 150 kg/h, dispositifs de sécurité associés et adaptateurs pour butane, propane et leurs mélanges
Druckregelgeräte, automatische Umschaltanlagen mit einem höchstem Ausgangsdruck bis einschließlich 4 bar und einem maximalen Durchfluss von 150 kg/h sowie die dazugehörigen Sicherheitseinrichtungen und Übergangsstücke für Butan, Propan und deren GemischeThis European Standard was approved by CEN on 9 March 2013.
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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16129:2013: ESIST EN 16129:2014

Special requirements for devices fitted with pressure or flow rate operated safety functions . 53 A.1 Regulating devices fitted with an over-pressure relief valve of a limited flow rate (PRV) . 53 A.1.1 Definition . 53 A.1.2 Constructional characteristics . 53 A.1.3 Performance characteristics . 53 A.1.4 Test methods . 54 A.1.5 Regulating device marking . 54 A.1.6 Instructions . 54 A.2 Regulating devices fitted with an over-pressure shut off safety device (OPSO) . 55 A.2.1 Definition . 55 A.2.2 Constructional characteristics . 55 A.2.3 Performance characteristics . 55 A.2.4 Test methods . 56 A.2.5 Regulating device marking . 57 A.2.6 Instructions . 57 A.3 Regulating devices fitted with an under-pressure shut off safety device (UPSO) . 57 A.3.1 Definition . 57 A.3.2 Constructional and performance characteristics . 57 A.3.3 Test methods . 57 A.3.4 Regulating device marking . 58 A.3.5 Instructions . 58 A.4 Regulating devices fitted with an excess flow valve (EFV) . 58 A.4.1 Definition . 58 A.4.2 Performance characteristics . 58 A.4.3 Test methods . 59 A.4.4 Regulating device marking . 62 A.4.5 Instructions . 62 A.5 Regulating devices fitted with a regulated outlet pressure limiter . 63 A.5.1 Definition . 63 A.5.2 Constructional and performance characteristics . 63 A.5.3 Test method . 63 SIST EN 16129:2014

Special requirements for devices fitted with a thermal shut off system . 68 B.1 Thermal shut off valve . 68 B.1.1 Definition . 68 B.1.2 Constructional characteristics . 68 B.1.3 Performance characteristics. 68 B.1.4 Test methods . 68 B.1.5 Marking . 69 B.1.6 Instructions . 69 B.2 Thermal spindle on devices for self closing valve connection . 69 B.2.1 Definition . 69 B.2.2 Constructional characteristics . 69 B.2.3 Performance characteristics. 69 B.2.4 Test methods . 70 B.2.5 Marking . 70 B.2.6 Instructions . 70 Annex C (normative)
Special requirements for devices under extreme temperature conditions (temperatures below -20 °C) . 71 C.1 Scope . 71 C.2 Requirements . 71 C.2.1 Material . 71 C.2.2 Extreme temperature test . 71 C.3 Conditioning . 71 C.4 Marking . 71 C.5 Instructions . 71 Annex D (normative)
Regulating devices for gas cylinders to supply appliances installed in caravans, motor caravans or freshwater boats . 72 D.1 Scope . 72 D.2 Installations and connections . 72 D.3 Pressures and flow rate . 74 D.4 Pressure safety functions . 75 D.5 Automatic change over system ("kit") . 75 D.6 Resistance to vibration . 76 D.7 Marking . 76 D.8 Instructions . 77 Annex E (normative)
Complementary test requirements for non-metallic thermoplastic or thermal setting materials used in the construction of devices . 78 E.1 Scope . 78 E.2 Materials . 78 E.3 Special requirements . 79 E.3.1 Accelerated ageing . 79 E.3.2 Resistance to hydrocarbons. 80 E.3.3 Resistance to cracking under stress and when chemical agents are present . 80 SIST EN 16129:2014

Requirements for elastomeric reinforced diaphragms. 82 Annex G (normative)
Inlet connections . 83 Annex H (normative)
Outlet connections . 98 Annex I (informative)
Test method for resistance to corrosion . 119 I.1 Principle . 119 I.2 Reagents . 119 I.2.1 Saline solution . 119 I.2.2 Compressed air. 119 I.2.3 Salt mist . 119 I.3 Apparatus . 120 I.4 Test method . 121 I.4.1 Method of exposure of devices . 121 I.4.2 Duration of tests . 121 I.4.3 Checks . 121 I.4.4 Cleaning of devices . 122 I.5 Results . 122 Annex J (informative)
Method for measuring leaks. 125 J.1 Scope . 125 J.2 Diagram of the test bench . 125 J.3 Coefficient K . 126 J.3.1 Method . 126 J.3.2 Calculations . 126 J.4 Measurement of the leak . 126 J.4.1 Method . 126 J.4.2 Calculations . 126 J.5 Checks . 127 Annex K (normative)
Special requirements for low pressure fixed regulators fitted with two or three outlets for outdoor use . 128 K.1 Scope . 128 K.2 Constructional characteristics . 128 K.3 Performance characteristics . 128 K.4 Test methods . 128 K.4.1 Test on the shut off devices . 128 K.4.2 Performance test . 129 K.5 Marking . 130 K.6 Instructions . 130 Annex L (normative)
Special requirements for regulators fitted with an inlet valve . 131 L.1 Scope . 131 L.2 Definition . 131 L.3 Constructional characteristics . 131 L.4 Performance characteristics : mechanical strength . 131 L.5 Test methods . 131 Annex M (normative)
Devices for gas cylinders to supply appliances installed in seawater boats . 132 M.1 Scope . 132 M.2 General . 132 M.3 Maximum guaranteed flow rate . 132 M.4 Regulating devices fitted with a pressure relief valve . 132 M.5 Vent . 132 M.6 Connections . 132 SIST EN 16129:2014

Alternative possible seal . 134 N.1 Scope . 134 N.2 Dimensions. 134 N.3 Materials . 134 N.4 Markings . 134 Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements of EU Directive 2009/142/EC (for pressure regulators only) . 136 Bibliography. 138
Key 1 pressure sensing subassembly (diaphragm a
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