Machines for underground mines - Safety requirements for hydraulic powered roof supports - Part 2: Power set legs and rams

This document stipulates the safety requirements for use of legs and rams as intended by the manufacturer. These include legs, support rams and rams, including the mechanical extensions, the inner valves and safety devices, seals, the hydraulic connections (up to the 1st hose line or to the valve of design B, see EN 1804-3:2020) and their lifting points, but excluding protective pipes and gaiters, external valves and hydraulic and electrohydraulic control systems.
NOTE   Some components are discussed in other parts of this standard series.
This document applies for legs, support rams, and cylinders that are used at ambient temperatures between -10 °C and 60 °C.
This document identifies and takes account of:
-   possible hazards which may be caused by the operation of legs, support rams and rams;
-   the hazardous areas and the operating conditions that can cause any type of hazard;
-   the situations that can result in hazards that cause an injury or impair health;
-   dangers that can be caused through mine gas and/or flammable dusts.
This document describes methods for reducing these hazards.
Clause 4 contains a list of the hazards discussed.
This document does not specify any additional requirements for:
-   specially corrosive environments;
-   risks associated with manufacturing and decommissioning;
-   earthquake.
A complete hydraulic powered roof support consists of the support units (EN 1804-1:2020), legs and support rams (EN 1804-2:2020) and the hydraulic and electro hydraulic controls (EN 1804-3:2020). Each part of this multipart document addresses the safety requirements of the components mentioned in the scopes of the respective parts of this multipart series.
This document is not applicable to legs and rams manufactured before the date of its publication.

Maschinen für den Bergbau unter Tage - Sicherheitsanforderungen für hydraulischen Schreitausbau - Teil 2: Stempel und Zylinder

Dieses Dokument legt die Sicherheitsanforderungen für die vom Hersteller vorgesehene bestimmungsgemäße Verwendung von Stempeln und Zylindern fest. Hierzu gehören Stempel, Stützzylinder und Zylinder einschließlich der mechanischen Verlängerungen, der inneren Ventile und Sicherheitseinrichtungen, der Dichtungselemente, der hydraulischen Anschlüsse (bis zur 1. Schlauchleitung oder zum Ventil der Bauart B, siehe EN 1804 3:2020) und der Hebepunkte, jedoch ausschließlich der Schutzrohre und -hüllen, der externen Ventile, der hydraulischen und elektrohydraulischen Steuerungseinrichtungen.
ANMERKUNG Einige Komponenten werden in anderen Teilen dieser Normenreihe behandelt.
Dieses Dokument gilt für Stempel, Stützzylinder und Zylinder, die bei Umgebungstemperaturen zwischen −10 °C und 60 °C eingesetzt werden.
Diese Norm identifiziert und berücksichtigt:
- Gefährdungen, die womöglich durch Stempel, Stützzylinder und Zylinder hervorgerufen werden;
- die Gefahrenbereiche und die Betriebsbedingungen, die irgendeine Art von Gefährdung verursachen können, und
- die Situationen, die zu Gefährdungen führen können, die eine Verletzung oder Gesundheitsschädigung verursachen;
- Gefahren, die durch Grubengas und/oder brennbare Stäube verursacht werden können.
Diese Norm beschreibt Verfahren zur Reduzierung dieser Gefährdungen.
Abschnitt 4 enthält eine Liste der behandelten Gefährdungen.
Dieses Dokument spezifiziert keine zusätzlichen Anforderungen für:
- besonders korrosive Umgebungen;
- Risiken bei Herstellung und Außerbetriebnahme;
- Erdbeben.
Ein kompletter hydraulischer Schreitausbau besteht aus den Ausbaugestellen (EN 1804 1:2020), Stempeln und Stützzylindern (EN 1804 2:2020) sowie den hydraulischen und elektrohydraulischen Steuerungseinrichtungen (EN 1804 3:2020). Die einzelnen Teile dieses mehrteiligen Dokuments befassen sich mit den Sicherheitsanforderungen der Komponenten, die in den Anwendungsbereichen der jeweiligen Teile dieser mehrteiligen Normenreihe genannt werden.
Dieses Dokument gilt nicht für Stempel und Zylinder, die vor dem Datum der Veröffentlichung dieses Dokuments hergestellt wurden.

Machines pour mines souterraines - Exigences de sécurité relatives aux soutènements marchants applicables aux piles - Partie 2 : Étançons et vérins à pose mécanisée

Le présent document stipule les exigences de sécurité relatives à l’utilisation des étançons et des vérins, telle que prévue par le fabricant. Ceux-ci comprennent les étançons, les vérins de soutènement et les vérins, y compris les rallonges mécaniques, les soupapes internes et les dispositifs de protection, les joints d’étanchéité, les raccords hydrauliques (y compris le 1er tuyau flexible ou la soupape de type B, voir l’EN 1804 3:2020) et leurs points de levage, mais à l’exclusion des tuyaux et gaines à cuir de protection, les soupapes externes, ainsi que les unités de commande hydrauliques et électro hydrauliques.
NOTE   Certains composants sont traités dans d’autres parties de la présente série de normes.
Le présent document s’applique aux étançons, vérins de soutènement et vérins qui sont utilisés à des températures ambiantes comprises entre −10 °C et 60 °C.
Le présent document identifie et tient compte :
-   des phénomènes dangereux potentiels pouvant résulter de l’utilisation des étançons, vérins de soutènement et vérins ;
-   des zones dangereuses et des conditions de fonctionnement susceptibles d’engendrer tout type de phénomène dangereux ;
-   des situations susceptibles d’engendrer des phénomènes dangereux pouvant entraîner des blessures ou porter atteinte à la santé ;
-   des dangers pouvant être causés par le gaz de mine (grisou) et/ou les poussières inflammables.
Le présent document décrit des méthodes permettant de réduire ces phénomènes dangereux.
L’Article 4 contient une liste des phénomènes dangereux traités.
Le présent document ne définit pas d’exigences supplémentaires concernant :
-   les milieux environnants particulièrement corrosifs ;
-   les risques associés à la fabrication et à la mise hors service ;
-   les tremblements de terre.
Un soutènement marchant complet est constitué des unités de soutènement (EN 1804-1:2020), des étançons et des vérins de soutènement (EN 1804-2:2020) et des systèmes de commande hydrauliques et électro-hydrauliques (EN 1804-3:2020). Chaque partie du présent document multipartie traite des exigences de sécurité des composants mentionnés dans le domaine d’application de la partie concernée.
Le présent document ne s’applique pas à tous les étançons et vérins fabriqués avant sa date de publication.

Stroji za podzemne rudnike - Varnostne zahteve za hidravlično podporje - 2. del: Hidravlične stojke in potisni hidravlični valji

General Information

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Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
23-Dec-2020
Completion Date
23-Dec-2020

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SLOVENSKI STANDARD
SIST EN 1804-2:2021
01-april-2021
Nadomešča:
SIST EN 1804-2:2002+A1:2010
Stroji za podzemne rudnike - Varnostne zahteve za hidravlično podporje - 2. del:
Hidravlične stojke in potisni hidravlični valji
Machines for underground mines - Safety requirements for hydraulic powered roof
supports - Part 2: Power set legs and rams

Maschinen für den Bergbau unter Tage - Sicherheitsanforderungen für hydraulischen

Schreitausbau - Teil 2: Stempel und Zylinder

Machines pour mines souterraines - Exigences de sécurité relatives aux soutènements

marchants applicables aux piles - Partie 2 : Etançons et vérins à pose mécanisée
Ta slovenski standard je istoveten z: EN 1804-2:2020
ICS:
73.100.10 Oprema za gradnjo predorov Tunnelling and tubbing
in podzemnih železnic equipment
SIST EN 1804-2:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 1804-2:2021
---------------------- Page: 2 ----------------------
SIST EN 1804-2:2021
EN 1804-2
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2020
EUROPÄISCHE NORM
ICS 73.100.10 Supersedes EN 1804-2:2001+A1:2010
English Version
Machines for underground mines - Safety requirements for
hydraulic powered roof supports - Part 2: Power set legs
and rams

Machines pour mines souterraines - Exigences de Maschinen für den Bergbau unter Tage -

sécurité relatives aux soutènements marchants Sicherheitsanforderungen für hydraulischen

applicables aux piles - Partie 2 : Étançons et vérins à Schreitausbau - Teil 2: Stempel und Zylinder

pose mécanisée
This European Standard was approved by CEN on 25 October 2020.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 1804-2:2020 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 1804-2:2021
EN 1804-2:2020 (E)
Contents Page

European foreword ............................................................................................................................................ 4

Introduction .......................................................................................................................................................... 5

1 Scope .......................................................................................................................................................... 6

2 Normative references .......................................................................................................................... 6

3 Terms and definitions ......................................................................................................................... 7

4 Safety requirements ............................................................................................................................ 9

4.1 General...................................................................................................................................................... 9

4.2 Lifting points ........................................................................................................................................... 9

4.3 Internal valves and safety devices .................................................................................................. 9

4.4 Pressurized fluids ............................................................................................................................... 10

4.5 Protection against ejecting fluids ................................................................................................. 10

4.6 Yield capability .................................................................................................................................... 10

4.7 Behaviour under axial overload .................................................................................................... 10

4.8 Eccentric loading ................................................................................................................................. 10

4.9 Functional reliability ......................................................................................................................... 10

4.10 Leak tightness ...................................................................................................................................... 10

4.11 Extension limit ..................................................................................................................................... 11

4.12 Force introduction points of actuators ....................................................................................... 11

4.13 Materials ................................................................................................................................................ 11

4.13.1 Steel.......................................................................................................................................................... 11

4.13.2 Light metal ............................................................................................................................................. 11

4.13.3 Materials other than steel ................................................................................................................ 11

4.13.4 Seals ......................................................................................................................................................... 12

4.14 Calculated permissible stresses .................................................................................................... 12

4.14.1 Permissible stresses under axial central rated force conditions ...................................... 12

4.14.2 Permissible stresses under double axial central rated force conditions ....................... 12

4.14.3 Permissible stresses under eccentric rated force conditions ............................................ 12

4.14.4 Permissible weld stresses ............................................................................................................... 12

4.15 Welding ................................................................................................................................................... 12

5 Verification of the safety requirements ...................................................................................... 13

5.1 Type testing ........................................................................................................................................... 13

5.2 Series verification ............................................................................................................................... 14

6 User information ................................................................................................................................. 14

6.1 General requirements ....................................................................................................................... 14

6.2 Technical and application data ...................................................................................................... 14

6.2.1 Introduction .......................................................................................................................................... 14

6.2.2 General description............................................................................................................................ 14

6.2.3 Performance data ............................................................................................................................... 14

6.2.4 Hydraulic data ...................................................................................................................................... 14

6.2.5 List of additional drawings and documents .............................................................................. 14

6.3 Handling, transport and storage ................................................................................................... 14

6.3.1 Introduction .......................................................................................................................................... 14

6.3.2 Handling and transport .................................................................................................................... 15

6.3.3 Storage .................................................................................................................................................... 15

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SIST EN 1804-2:2021
EN 1804-2:2020 (E)

6.4 Installation, commissioning, and operation ............................................................................. 15

6.4.1 Installation ............................................................................................................................................ 15

6.4.2 Commissioning .................................................................................................................................... 15

6.4.3 Operation ............................................................................................................................................... 15

6.5 Maintenance ......................................................................................................................................... 16

6.5.1 Introduction ......................................................................................................................................... 16

6.5.2 Maintenance instructions ................................................................................................................ 16

6.5.3 Fault diagnosis and correction ...................................................................................................... 16

6.5.4 Preventative maintenance schedules ......................................................................................... 16

6.5.5 Technical description ........................................................................................................................ 16

6.6 Parts identification lists ................................................................................................................... 16

6.7 Marking / Identification ................................................................................................................... 17

6.8 Residual risk ......................................................................................................................................... 17

Annex A (normative) Tests for verification of the safety requirements ...................................... 18

A.1 Load tests ............................................................................................................................................... 18

A.1.1 General ................................................................................................................................................... 18

A.1.2 Testing with a central axial load ................................................................................................... 18

A.1.3 Testing with eccentric force............................................................................................................ 20

A.1.4 Life test ................................................................................................................................................... 20

A.1.5 Testing of lifting points ..................................................................................................................... 22

A.2 Static calculation of actuators ........................................................................................................ 23

A.2.1 General ................................................................................................................................................... 23

A.2.2 Axial stresses ........................................................................................................................................ 23

A.2.3 Tangential stresses ............................................................................................................................ 27

A.2.4 Radial stresses ..................................................................................................................................... 27

A.2.5 Combined stresses ............................................................................................................................. 27

A.2.6 Individual components ..................................................................................................................... 28

A.2.7 Symbols and units............................................................................................................................... 29

A.3 Testing the material properties .................................................................................................... 29

A.3.1 General ................................................................................................................................................... 29

A.3.2 Weldability ............................................................................................................................................ 29

A.3.3 Mechanical properties ...................................................................................................................... 30

A.3.4 Impact value ......................................................................................................................................... 30

Annex B (informative) List of tests ............................................................................................................ 31

Annex C (informative) List of significant hazards ................................................................................ 37

Annex ZA (informative) Relationship between this European Standard and the essential

requirements of Directive 2006/42/EC aimed to be covered ............................................ 40

Bibliography ....................................................................................................................................................... 42

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SIST EN 1804-2:2021
EN 1804-2:2020 (E)
European foreword

This document (EN 1804-2:2020) has been prepared by Technical Committee CEN/TC 196 “Mining

machinery and equipment - Safety”, the secretariat 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 June 2021, and conflicting national standards shall be

withdrawn at the latest by June 2021.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 1804-2:2001+A1:2010.

The main differences between this document and EN 1804-2:2001+A1:2010 are as follows:

a) Normative references (updated);
b) Terms and definitions (modified);
c) List of significant hazards (revised) (see Annex C);
d) Requirements for steel (updated/modified);
e) Requirements for static and dynamic overload (revised/modified);
f) Requirements for overload fully retracted (deleted);
g) List of tests (updated) (see Annex B).

This document has been prepared under a mandate given to CEN by the European Commission and the

European Free Trade Association and supports essential requirements of EU Directive(s).

For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this

document.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,

Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,

Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North

Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United

Kingdom.
---------------------- Page: 6 ----------------------
SIST EN 1804-2:2021
EN 1804-2:2020 (E)
Introduction
This document is a type C standard, as specified in EN ISO 12100:2010.

The machinery concerned and the extent to which hazards, hazardous situations and events are covered

are indicated in the scope of this document.

This document is of relevance, in particular, for the following stakeholder groups representing the market

players with regard to machinery safety:
— machine manufacturers (small, medium and large enterprises);

— health and safety bodies (regulators, accident prevention organizations, market surveillance, etc.).

Others can be affected by the level of machinery safety achieved with the means of the document by the

above-mentioned stakeholder groups:
— machine users/employers (small, medium and large enterprises);

— machine users/employees (e.g. trade unions, organizations for people with special needs);

— service providers, e.g. for maintenance (small, medium and large enterprises);
— consumers (in the case of machinery intended for use by consumers).

The above-mentioned stakeholder groups have been given the possibility to participate at the drafting

process of this document.

The machinery concerned and the extent to which hazards, hazardous situations or hazardous events are

covered are indicated in the Scope of this document.

When requirements of this type-C standard are different from those which are stated in type-A or type-B

standards, the requirements of this type-C standard take precedence over the requirements of the other

standards for machines that have been designed and built according to the requirements of this type-C

standard.

The extent to which hazards are covered is indicated in the scope of this document. When drawing up

this standard, the underlying assumptions were that:
— only trained and qualified personnel operate the machine;
— components without specific requirements are:

— designed in accordance with the usual engineering practice and calculation codes;

— of sound mechanical construction;
— are free of defects;
— components are kept in good working order;

— the implementation conditions and requirements imposed on the machine have been agreed

between manufacturer of the legs and cylinders and their user (manufacturers of the support unit or

users in the case of spare parts).
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SIST EN 1804-2:2021
EN 1804-2:2020 (E)
1 Scope

This document stipulates the safety requirements for use of legs and rams as intended by the

manufacturer. These include legs, support rams and rams, including the mechanical extensions, the inner

valves and safety devices, seals, the hydraulic connections (up to the 1st hose line or to the valve of design

B, see EN 1804-3:2020) and their lifting points, but excluding protective pipes and gaiters, external valves

and hydraulic and electrohydraulic control systems.
NOTE Some components are discussed in other parts of this standard series.

This document applies for legs, support rams, and cylinders that are used at ambient temperatures

between –10 °C and 60 °C.
This document identifies and takes account of:

— possible hazards which may be caused by the operation of legs, support rams and rams;

— the hazardous areas and the operating conditions that can cause any type of hazard;

— the situations that can result in hazards that cause an injury or impair health;

— dangers that can be caused through mine gas and/or flammable dusts.
This document describes methods for reducing these hazards.
Clause 4 contains a list of the hazards discussed.
This document does not specify any additional requirements for:
— specially corrosive environments;
— risks associated with manufacturing and decommissioning;
— earthquake.

A complete hydraulic powered roof support consists of the support units (EN 1804-1:2020), legs and

support rams (EN 1804-2:2020) and the hydraulic and electro hydraulic controls (EN 1804-3:2020).

Each part of this multipart document addresses the safety requirements of the components mentioned

in the scopes of the respective parts of this multipart series.

This document is not applicable to legs and rams manufactured before the date of its publication.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 1090-1:2009+A1:2011, Execution of steel structures and aluminium structures — Part 1: Requirements

for conformity assessment of structural components

EN 1804-1:2020, Machines for underground mines — Safety requirements for hydraulic powered roof

supports — Part 1: Support units and general requirements

EN 1804-3:2020, Machines for underground mines — Safety requirements for hydraulic powered roof

supports — Part 3: Hydraulic and electro hydraulic control systems
EN 10204:2004, Metallic products — Types of inspection documents
---------------------- Page: 8 ----------------------
SIST EN 1804-2:2021
EN 1804-2:2020 (E)

EN ISO 148-1:2016, Metallic materials — Charpy pendulum impact test — Part 1: Test method

(ISO 148-1:2016)

EN ISO 643:2020, Steels — Micrographic determination of the apparent grain size (ISO 643:2019,

Corrected version 2020-03)

EN ISO 6892-1:2019, Metallic materials — Tensile testing — Part 1: Method of test at room temperature

(ISO 6892-1:2019)

EN ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk

reduction (ISO 12100:2010)

EN ISO 15614-1:2017, Specification and qualification of welding procedures for metallic materials —

Welding procedure test — Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys

(ISO 15614-1:2017, Corrected version 2017-10-01)

EN ISO 80079-36:2016, Explosive atmospheres — Part 36: Non-electrical equipment for explosive

atmospheres — Basic method and requirements (ISO 80079-36:2016)

ISO 7745:2010, Hydraulic fluid power — Fire-resistant (FR) fluids — Requirements and guidelines for use

3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN ISO 12100:2010,

EN 1804-1:2020, EN 1804-3:2020 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
support unit

type of hydraulic powered roof support, e.g. frame support, chock support, shield support, consisting of

support components and support accessories
[SOURCE: EN 1804-1:2020, definition 3.1.1]
3.2
support components
all components which lie within the flow of the support bearing force
3.2.1
actuator
any type of hydraulic linear reciprocating device referred to in this document
3.2.2
legs and support rams
hydraulic actuators for producing the support bearing force of the support unit
As impacted by EN ISO 15614-1:2017/A1:2019.
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SIST EN 1804-2:2021
EN 1804-2:2020 (E)
3.2.3
single telescopic legs and support rams
hydraulic legs and support rams with one extension stage
3.2.4
multi telescopic legs and support rams
hydraulic legs and support rams with several extension stages
3.3
rams

all actuators which do not lie within the flow of the support bearing force but which are necessary for the

functioning of the powered roof support
3.4
control devices
3.4.1
valve
device for controlling the flow of hydraulic fluid
3.4.2
bursting blank
single acting hydraulic fuse
3.4.3
internal valve
valve inside actuator without access from outside
3.4.4
external valve
valve attached outside of the actuator
3.4.5
safety devices
type A valves according to EN 1804-3:2020
3.5
pressures
3.5.1
setting pressure

hydraulic pressure in the legs and support rams on completion of the setting procedure

Note 1 to entry: This pressure is supplied by the hydraulic system.
3.5.2
yield pressure of an actuator

hydraulic pressure in an actuator when the relevant pressure limiting valve is opened

Note 1 to entry: This pressure in the actuator is induced by external forces (yield forces; see EN 1804-1:2020,

3.5.1).
3.5.3
maximum permissible working pressure of an actuator

maximum hydraulic pressure at which a hydraulic component is intended be operated and/or yielded

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SIST EN 1804-2:2021
EN 1804-2:2020 (E)
3.6
rated actuator force
maximum force to which an actuator is designed

Note 1 to entry: It is a calculated value which is determined from the actuator geometry and the maximum

permissible working pressure, neglecting friction.
3.7
functions
3.7.1
extension
pushing out of the actuator operating piston by means of hydraulic pressure
3.7.2
retraction
drawing in of the actuator operating piston by means of hydraulic pressure
3.7.3
setting

extending of the support unit between the roof and the floor by pressuring the legs and support rams

3.7.4
yielding

alteration in length of an actuator which occurs when external forces cause the yield pressure to be

exceeded
4 Safety requirements
4.1 General

Machinery shall comply with the safety requirements and/or protective/risk reduction measures of this

clause. In addition, the machine shall be designed according to the principles of EN ISO 12100:2010 for

relevant but not significant hazards which are not dealt with by this document.
4.2 Lifting points

Where lifting points are fitted to actuators they shall be suitable for their intended purpose. They shall

be designed to have a calculated minimum factor of safety of 4 on ultimate breaking load in relation to

their intended load carrying capacity. They shall be clearly and permanently marked with their load

carrying capacity, e.g. by welding.
4.3 Internal valves and safety devices

Actuators that can be externally overloaded shall be protected against excessive pressure.

This can be by means of:
— internal valves;
— external valves (see EN 1804-3:2020);
— safety devices such as bursting blanks.

The pressure in the piston compartment of hydraulic legs shall be capable of being monitored so that

leakages are recognized in good time and hazards from inadequate strata control as a result of a pressure

drop in the legs are avoided.
---------------------- Page: 11 ----------------------
SIST EN 1804-2:2021
EN 1804-2:2020 (E)

As a result of the type of fluid used and the small number of pressure cycles per day, actuators of hydraulic

powered roof supports need neither to be self-bleeding nor shall they have external air bleeds.

In addition, internal valves, excluding constant yield valves, are covered by EN 1804-3:2020.

4.4 Pressurized fluids
Actuators shall be either designed such that they use:

a) fire-resistant fluids category HFA (ISO 7745:2010) specified by the support unit manufacturer in

accordance with ISO 7745:2010, 6.2.1;
b) water without additives (temperatures from +5 °C to +60 °C).

Hydraulic systems of roof supports, designed for coal mines and other mines with potentially explosive

atmospheres, should be designed for use with non-toxic and fire-resistant fluids in accordance with

SHCMOEI 7th Report (see Bibliography).
4.5 Protection against ejecting fluids

Actuators that intentionally eject fluid in to the atmosphere shall be designed to prevent any hazard due

to the releasing fluid (e.g. by means of a guard).
4.6 Yield capability

Legs and support rams shall be designed such that at yield pressure they are capable of supporting the

forces and the movements of attached components, see Annex A and see EN 1804-1:2020, 4.3.1.

4.7 Behaviour under axial overload

Legs and support rams, including their mechanical extensions, shall be designed so that their function is

not
...

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