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ISO 4413 and ISO 4414: Safety Rules for Hydraulic and Pneumatic Machinery

ISO 4413:2010 and ISO 4414:2010 are the International Standards of general rules and safety requirements for hydraulic and pneumatic fluid power systems and their components used on machinery. UTEC Industrial designs, engineers, machines, fabricates, and installs custom material handling systems for aerospace and heavy industry from its Spokane Valley, WA facility, integrating Allen-Bradley PLC and motion control with in-house CNC machining, heat treating, and stress relief. This article sets out what the two standards' published scopes include and exclude, how they came to their 2010 form, where they sit beside ISO 13849-1 and US practice, and which circuit topics a buyer checks against them: pressure limitation, accumulators, load holding, loss of power, fluid cleanliness, and air exhaust. The standards act at the design and engineering links of the chain, design → engineering → parts machining → fabrication → assembly → weld fatigue → stress relief → drives → controls → tuning → monitoring, and they fix the relief, filtration, and exhaust points that the controls and monitoring links later watch.

What do ISO 4413:2010 and ISO 4414:2010 cover?​

ISO 4413:2010 "specifies general rules and safety requirements for hydraulic fluid power systems and components used on machinery as defined by ISO 12100." Its abstract says it "deals with all significant hazards associated with hydraulic fluid power systems and specifies the principles to apply in order to avoid those hazards when the systems are put to their intended use." It applies to the design, construction and modification of systems and their components, and the abstract says it also takes into account these aspects:

  • assembly, installation, and adjustment;
  • uninterrupted system operation;
  • ease and economy of maintenance and cleaning;
  • reliable operation in all intended uses;
  • energy efficiency and environment.

ISO 4414:2010 has a parallel abstract for pneumatic fluid power systems and components used on machinery as defined by ISO 12100, with the same list of aspects. It adds one boundary: it "does not apply to air compressors and the systems associated with air distribution as typically installed in a factory, including gas bottles and receivers." How that boundary divides a specification between the machine's pneumatics and the plant air is covered in the cold, dusty mills pneumatics article.

Both are Edition 3, published 2010-11 by ISO/TC 131/SC 9, at 46 pages (ISO 4413) and 38 pages (ISO 4414). Each replaced its 1998 edition, and each iso.org page reads "This publication was last reviewed and confirmed in 2021. Therefore this version remains current." Titles, scopes, and editions here come from the publisher's pages; clause-level statements are confirmed against the purchased texts (ISO 4413:2010; ISO 4414:2010).

Where did the two standards come from, and what did the 2010 revision change?​

Jerry Carlin, past chair of ISO TC 131/SC9 (2003–2015), gives the history in a 2017 Fluid Power Journal article. As he tells it:

  • Early 1950s: formal standardization of hydraulic and pneumatic systems best practices began through the Joint Industrial Council (JIC), made up of automotive manufacturing experts.
  • 1970s: ISO TC131/SC9 addressed the subject, "resulting in the release of ISO 4413 and 4414 standards for stationary hydraulic and pneumatic equipment."
  • 1981: the JIC was dissolved and reached an agreement with the National Fluid Power Association to have the JIC fluid power standards updated and issued as ANSI/NFPA standards.
  • Around 1990 to 1998: the NFPA Systems Technical Committee released national standards, "with much of that work later incorporated into updates of the ISO standards in 1998."
  • 1995 to 2010: CEN issued EN 982 and EN 983 for the EU Machinery Directive; they "were eventually withdrawn when ISO 4413 and 4414 were updated in 2010 to include many of the safety-related provisions in the EN standards."

Carlin lists four goals that he says ISO TC131/SC9 established and achieved for the 2010 revision. They were to integrate the safety provisions of EN 982:1996 and comply with Machinery Directive 2006/42/EC; to expand the scope of ISO 4413 to include mobile equipment; to revise ISO 4413 and ISO 4414 through separate working groups but concurrently, with a common style, structure, and schedule; and to "Integrate into 4413 the significant U.S. national preferences and practices of the NFPA T2.24.1 supplement and the NFPA reservoir standards." The mobile-equipment expansion is Carlin's statement; the iso.org abstract says "machinery as defined by ISO 12100" and does not use the word "mobile." The Machinery Directive goal is an EU requirement, not a US one (Carlin J 2017; ISO 4413:2010).

Where do ISO 4413 and ISO 4414 sit among machinery safety standards?​

Carlin places both standards in the three-type hierarchy of ISO machinery safety standards and writes that "Provisions of a Type C standard take precedence over those of a Type B standard such as ISO 4413 or 4414 when there are conflicts or differences." ISO 12100:2010, which "specifies basic terminology, principles and a methodology for achieving safety in the design of machinery," says it is "also intended to be used as a basis for the preparation of type-B or type-C safety standards." Its iso.org page shows it at stage 90.92, "Expected to be replaced by ISO/DIS 12100.3 within the coming months."

Carlin also writes that one of the first steps in a fluid power system safety evaluation is a risk assessment, and that "ISO 4413 and 4414 help facilitate this process by providing a list of hazards, as well as many other suggestions and rules." The documents his article names for that step, ISO 14121-1 for the risk assessment and ISO 12100-1 for the risk-elimination hierarchy, are listed as withdrawn on the iso.org page of ISO 12100:2010. ISO 4413:2010 contains a list of the significant hazards it deals with.

Carlin adds that the standards "contain component and system guidance for improved system efficiency," though they "do not deal with efficiency determination directly," and that the viewpoints of purchaser and supplier are both considered, with "agreement between those parties" stressed. He adds: "The complete system life cycle is covered from design, assembly, and installation to maintenance and disposal." For a buyer, as engineering reasoning, that agreement language means the purchase specification is where operating conditions, pressures, and fluids are written down for the supplier to design to (Carlin J 2017; ISO 12100:2010; ISO 4413:2010; ISO 4414:2010).

How do ISO 4413 and ISO 4414 relate to ISO 13849-1 safety functions?​

ISO 13849-1:2023 "specifies a methodology and provides related requirements, recommendations and guidance for the design and integration of safety-related parts of control systems (SRP/CS) that perform safety functions, including the design of software." It applies to SRP/CS for high demand and continuous modes of operation "regardless of the type of technology and energy (e.g. electrical, hydraulic, pneumatic, and mechanical)," it does not apply to low demand mode of operation, and it "does not give specific requirements for the design of products/components that are parts of SRP/CS."

The IFA, the Institute for Occupational Safety and Health of the German Social Accident Insurance (DGUV), draws the line for fluid power in its Report 2/2017e, which describes the 2015 edition of ISO 13849-1:

  • "On fluid power installations, the area of valves, i.e. valves controlling hazardous movements or states, should in particular be considered a 'safety-related part of the control system'."
  • "The drive elements and the components for energy conversions and transmission in fluid power systems generally lie outside the scope of the standard."
  • On hydraulic systems, "measures for pressure limitation in the system ... and for filtration of the hydraulic fluid ... must also be considered in this context."
  • The requirements that fluid power systems must meet "are described in full in" its references 58 and 59, which are EN ISO 4413 and EN ISO 4414 (2010).

IFA Report 1/2025, which describes the 2023 edition, carries the same scope text for fluid-power controls in its §11.1.2 (in German; paraphrase translated from the German). As engineering reasoning, the pump, cylinders, relief valve, and filtration are then specified to ISO 4413 or ISO 4414, and the valves that stop or hold a hazardous movement are also designed to ISO 13849-1. That second part is the subject of this category's ISO 13849-1 article (ISO 13849-1:2023; Hauke M, Schaefer M, Apfeld R, et al., IFA Report 2/2017e, 2019, pp. 101-102; Hauke M, Bömer T, Werner C, et al., IFA Report 1/2025, pp. 125-126).

What do the standards expect for pressure limitation on a hydraulic system?​

ISO 4413:2010 requires the system to be protected against pressure exceeding its maximum working pressure, for example by a pressure relief valve. IFA Report 2/2017e, describing the 2015 edition of ISO 13849-1, lists pressure limitation among the measures that "must also be considered" on hydraulic systems. In its description of the 2012 edition of ISO 13849-2, it names pressure limitation among the most important basic safety principles for hydraulic systems, with isolation, protection against unexpected start-up, suitable materials and manufacturing procedures, and a suitable temperature range.

Supplier data show what a relief valve brings to the circuit. Bosch Rexroth's data sheet for one of its direct-operated pressure relief valves gives "MTTFD values according to EN ISO 13849" of "150 ... 1200" years, "for more information see data sheet 08012"; the data sheet does not say which value applies at which operating frequency. For the type-examination tested safety-valve version, Rexroth writes that "Discharge lines of safety valves must end in a risk-free manner" and that "An accumulation of fluids in the discharge system must not be possible." The same page states that, under the Pressure Equipment Directive 2014/68/EU, the increase in system pressure due to flow "must not exceed 10% of the set response pressure"; that is an EU directive requirement as Rexroth states it, not a US rule. Rexroth also notes that the maximum flow stated in the component marking "applies for applications without counter pressure in the discharge line (port T)." HYDAC's accumulator safety block brochure says the tank piping "must be installed separately," so that flow "can be channelled away to the tank unpressurised" when its relief valve opens.

Rexroth's data sheet names the failure mode these provisions guard against, a back-pressured relief path: "Hydraulic counter pressures in port T add 1:1 to the response pressure of the valve," and "The system pressure increases by the counter pressure in the discharge line (port T) due to the increasing flow" (ISO 4413:2010; Hauke M, Schaefer M, Apfeld R, et al., IFA Report 2/2017e, 2019, pp. 101, 268; Bosch Rexroth AG, Data sheet RE 25402, 2021, pp. 5, 19; HYDAC Technology GmbH, brochure EN 3551.25/05.24, 2024, §1.2.2).

What do the standards expect for hydraulic accumulators?​

ISO 4413:2010 requires a hydraulic circuit with a gas-loaded accumulator to discharge the accumulator's fluid pressure automatically, or to isolate the accumulator, when the machine is switched off. The accumulator manuals, the five-feature safety and shut-off block that HYDAC recommends, and the discharge-and-verify sequence are covered in the stored-energy and lockout article and are not repeated here.

One hardware distinction matters when the specification is written. HYDAC's brochure for its safety and shut-off block says the block "takes into account the applicable safety regulations according to DIN EN ISO 4413 and the German Industrial Safety Regulation (BetrSichV)"; the brochure names no ISO 4413 clause, and BetrSichV is German law. The block "consists of a valve block, an integrated HYDAC pressure relief valve, a main shut-off valve and a manually operated pressure release valve," and "an optional solenoid-operated 2-way directional valve allows automatic discharge of the accumulator or consumer and therefore of the hydraulic system in an emergency or for shut-down." In the logic-element version with a 3/2 directional poppet valve, by contrast, if the pump "breaks down or if it is switched off," the accumulator pressure "shuts off the hydraulic accumulator from the system." HYDAC describes that version as isolating the charged accumulator and describes no discharge path for it, while for its 4/2-valve logic-element version the brochure adds that, with the accumulator connected to tank through the orifice in the pilot valve, "it will slowly discharge."

As engineering reasoning, a specification that asks only for "an accumulator safety block" can therefore receive either behaviour, so it states which one is required at shutdown, and the circuit diagram shows it (ISO 4413:2010; HYDAC Technology GmbH, brochure EN 3551.25/05.24, 2024, §1.1, §1.2, §5.5.1-§5.5.2).

How should a cylinder hold its load when pressure or power is lost?​

ISO 4413:2010 requires measures to prevent unintended movement of a load held by a cylinder, for example after a loss of pressure, and requires that the loss or restoration of power does not create a hazard such as unexpected start-up. ISO 14118:2017 "specifies requirements for designed-in means aimed at preventing unexpected machine start-up ... to allow safe human interventions in danger zones," and it applies to unexpected start-up from all types of energy source, including stored energy due to gravity or compressed springs; it does not specify performance levels or the means for specific machines. The IFA's summary of the 2023 edition of ISO 13849-1 says a safety function specification now includes "behaviour of the machine in the event of energy loss, e.g. a requirement for non-return valves directly on a cylinder or additional mechanical brakes," and that this can be split into two safety functions, "one with available energy or a second one without available energy."

Rexroth's note on compact hydraulics lists, among the requirements for components employed in safety-related parts of control systems, "Automatic reset to basic settings in the event of a power failure" and "Reliable maintenance of the basic settings." How trapped oil and load-holding valves can still release a raised load during service is covered in the stored-energy article, and how a closed-loop proportional valve powers down on loss of supply, enable, or command is covered in the closed-loop hydraulic control article.

The named failure mode is hose failure: Sun Hydraulics says its counterbalance and pilot-to-open check cartridges "can be mounted in, at, or near cylinders and motors to protect against hose failure." As engineering reasoning, a load-holding valve at the cylinder port keeps the oil column in the cylinder when a hose between it and the power unit fails, which a valve on the power unit cannot do (ISO 4413:2010; ISO 14118:2017; Hauke M, Bömer T, Büllesbach K-H, DGUV 2023, §5, pp. 3-4; Bosch Rexroth Oil Control S.p.A., RE 18350-51/04.25, 2025, p. 2; Sun Hydraulics Pub. 999-901-287, 2023, p. 1).

What do the standards say about fluid cleanliness and filtration?​

ISO 4413:2010 requires the fluid cleanliness level of a system to be stated, expressed by the code of ISO 4406, and to be suitable for the most contamination-sensitive component, and requires filtration to maintain it. ISO 4406:2021 "specifies the code to be used in defining the quantity of solid particles in the fluid used in a given hydraulic fluid power system"; it defines the code, not a limit, and the limits below are each supplier's own.

The suppliers' figures differ by component. HYDAC's accumulator safety block gives a maximum permitted contamination level of "ISO 4406 Class 21/19/16 or SAE AS 4059 Class 11." Rexroth's compact-hydraulics note says to "maintain the cleanliness of the hydraulic fluid over the entire period of use" and ties the 20-year maximum period of use, which it attributes to ISO 13849-1:2023, to cleanliness "according to ISO 4406:1999." Why proportional and servo valves need tighter codes is covered in the proportional versus servo valves article.

Field data tie valve life to operating conditions. IFA Report 2/2017e summarizes BIA-Report 6/2004, a study of hydraulic directional control valves in the maintenance departments of two transmission production plants. At User A, 143 of approximately 8,050 valves failed over 38 months, which gives an MTTFD of 178 years if a constant failure rate is assumed. At User B, with approximately 25,000 valves, the MTTFD rose from 195 years in 2000 to 300 in 2003; the report relates this to maintenance measures and operating conditions that were improved continually over the years, and says User B's conditions were superior to User A's owing to further measures such as monitoring of the fluid temperature, larger fluid reservoirs generally located outside the machine, and finer return line filters (ISO 4413:2010; ISO 4406:2021; HYDAC Technology GmbH, brochure EN 3551.25/05.24, 2024, §1.3.1; Bosch Rexroth Oil Control S.p.A., RE 18350-51/04.25, 2025, p. 2; Hauke M, Schaefer M, Apfeld R, et al., IFA Report 2/2017e, 2019, pp. 267-268).

How does ISO 4414 treat exhausting and isolating the air supply?​

ISO 4414:2010 requires a means of isolating the pneumatic system from its air supply and of exhausting the pressure downstream of it, so that the system can be made pressure-free before maintenance, and it addresses controlled pressurization on start-up, such as a soft-start valve. IFA notes that on pneumatic systems "an exhaust valve is frequently used in conjunction with a pressure switch" to control energy conversions safely.

A dual-spool safety exhaust valve shows the conditions a supplier attaches to that function. SMC's instruction manual says its safety instructions "must be followed in addition to International Standards (ISO/IEC)," and the first standard its footnote lists is ISO 4414. It states that the intended use "is to vent a protected system to atmosphere when it is de-energised" and "to prevent unexpected pressurisation of the protected system when in a de-energised state," and that "When properly integrated into a suitable safety control system" the valves are compatible for use in systems up to Category 4 PL e as defined by EN ISO 13849-1. The time taken to vent "is a function of" the valve's flow capacity, the silencer restriction, the protected volume, the air pressure in the protected system, and its flow restrictions; the end user "is expected to establish the time taken to vent." The manual warns that if operating pressure falls below 0.25 MPa because of insufficient air supply capacity, the valve "may not switch properly."

OSHA's 2021 letter on pneumatic fail-closed valves shows the lockout side of the line, for process valves on a pump rather than a machine safety circuit. The valves had been closed and de-energized for pump maintenance by disconnecting their air tubing and locking the tube ends. Asked whether locking out the air supply that way would comply with 1910.147, OSHA answered "No": the valve "in its current configuration does not meet the definition of an energy isolating device as defined by 29 CFR § 1910.147(b) since it is not capable of being locked out," and disconnecting the tubing fails because "'dismantling' ... would be necessary for a zero energy state to exist." As engineering reasoning by analogy, a de-energized safety exhaust valve is a safety function, not the energy isolating device for lockout. Residual air and lockout practice are covered in the stored-energy article (ISO 4414:2010; Hauke M, Schaefer M, Apfeld R, et al., IFA Report 2/2017e, 2019, p. 101; SMC Corporation, Doc. no. VPX400-TF224-035EN, 2024, pp. 1-2, §8.10; OSHA Standard Interpretation 2021).

What does ISO 4414 expect of air treatment on the machine?​

ISO 4414:2010 requires the compressed air supplied to a pneumatic system to be treated to the quality its components need, and it refers to ISO 8573-1 for stating that quality. The classes, pressure dew point, and freezing in cold plants are covered in the cold, dusty mills pneumatics article; this answer adds what sits on the machine itself.

IFA describes the maintenance unit in its pneumatic circuit examples as generally consisting of "a manual shut-off valve 0V10, a filter with water separator 0Z10 with monitoring of the contamination of the filter, and a pressure control valve 0V11 (with adequately dimensioned secondary venting)," with a pressure indicator 0Z11 that "satisfies the requirement for monitoring of the system parameters." It adds that on pneumatic systems the components for preventing hazards from energy conversion and the maintenance unit "must be considered from a safety perspective in conjunction with the valve area." Festo's general operating conditions put the supplier's side of it plainly: "The pneumatic components must be supplied with correctly prepared compressed air free of aggressive media."

As engineering reasoning, the failure mode is a valve that sticks or switches late because of water, oil, or particles in its air, which turns an air-quality fault into a safety-function fault on the valves that IFA counts as part of the control system (ISO 4414:2010; ISO 8573-1:2010; Hauke M, Schaefer M, Apfeld R, et al., IFA Report 2/2017e, 2019, pp. 101-102; Festo SE & Co. KG, General Operating Conditions, 2026, p. 1).

What does a US specification cite alongside ISO 4413 and ISO 4414?​

The National Fluid Power Association, the fluid power trade association (not the fire-code body), publishes what it describes as "a complete list of active NFPA Standards," and the list includes no US supplement to ISO 4413 or ISO 4414. NFPA/T2.24.1, the supplement whose U.S. national preferences and practices Carlin says were integrated into ISO 4413 in 2010, is not on it.

The active list includes component standards and test methods such as:

  • NFPA/T2.12.11-1 R1-2009 (R2024), fluid power systems and components reliability analysis, field data reporting format and database compilation;
  • NFPA/T2.12.11-2-2007 (R2024), hydraulic fluid power components assessment of reliability by testing;
  • NFPA/T2.24.2 R1-2007 (R2024), hydraulic fluid power systems methods for preventing external leakage;
  • NFPA/T3.5.24-2001 (R2024), pressure relief valves method of testing and presenting basic performance data;
  • NFPA/T3.4.7 R2-2000 (R2024), the pressure rating method for the pressure-containing envelope of a metal fluid power accumulator, which is a fatigue and burst rating method, not an accumulator safety or lockout standard.

For energy control, the federal OSHA rule is 29 CFR 1910.147. Apart from the employment and activities that paragraph (a)(1)(ii) excludes, such as construction and agriculture, it covers servicing and maintenance in which "the unexpected energization or start up of the machines or equipment, or release of stored energy could cause injury to employees," defines an energy isolating device, and requires that, after lockout or tagout devices are applied, "all potentially hazardous stored or residual energy shall be relieved, disconnected, restrained, and otherwise rendered safe." As engineering reasoning, the EU and German legal references printed in supplier documents (the Pressure Equipment Directive, the Machinery Directive, BetrSichV) describe how those products meet European law; they do not state US requirements (National Fluid Power Association 2024; Carlin J 2017; NFPA/T3.4.7 R2-2000; OSHA 29 CFR 1910.147-1989).

What controls and sensing does an ISO 4413 or ISO 4414 circuit need?​

The sensing named in the sources sits at the power unit, the accumulator, and the valve bank:

  • Fluid condition on the power unit. IFA's hydraulic example shows a reservoir breather filter that "prevents the ingress of external dirt," a fluid level indicator that "ensures that the fluid level remains within the specified limits," and a temperature indicator that constitutes a suitable measure for limiting the operating temperature range and thus the viscosity range of the fluid; it says these "are present in the majority of hydraulic systems."
  • Pressure at the accumulator. HYDAC's safety block provides "The necessary pressure gauge connections" and an optional solenoid-operated release valve.
  • Pressure behind an exhaust valve. IFA's pneumatic examples pair the exhaust valve with a pressure switch; SMC's safety exhaust valve carries pressure sensors whose data "should be confirmed" on every switch-on or switch-off, an on-demand test it says "shall be performed automatically by a safety controller."
  • Filter condition. IFA's maintenance unit includes monitoring of the contamination of the filter.

As engineering reasoning, the PLC reads these signals for alarms, permissives, and condition trends, while the stop and hold functions themselves run on safety-related parts of the control system designed to ISO 13849-1. The proportional versus servo valves article covers one valve maker's statement that its spool feedback signal must not be used to switch off safety-relevant machine functions. UTEC Industrial builds UL 508A control panels and programs Allen-Bradley ControlLogix and CompactLogix controllers with PanelView HMIs for the hydraulic and pneumatic machines it fabricates (Hauke M, Schaefer M, Apfeld R, et al., IFA Report 2/2017e, 2019, pp. 101-102; HYDAC Technology GmbH, brochure EN 3551.25/05.24, 2024, §1.2, §1.2.1; SMC Corporation, Doc. no. VPX400-TF224-035EN, 2024, §4.1).

Where do ISO 4413 and ISO 4414 sit in the design-to-monitoring chain?​

Carlin writes that the standards cover "The complete system life cycle ... from design, assembly, and installation to maintenance and disposal." ISO 4413:2010 and ISO 4414:2010 also require the information for use to include a circuit diagram to ISO 1219. Along the chain, as engineering reasoning, the fluid-power provisions fall at these links:

  • Design and engineering: the circuit diagram, maximum working pressures, relief settings, accumulator discharge or isolation at shutdown, load-holding valves at the cylinder ports, and the cleanliness code.
  • Parts machining, fabrication, and assembly: manifold and cylinder mounting faces, reservoir and tank-line routing, and pipe supports on welded frames.
  • Weld fatigue and stress relief: the welded frame that carries the cylinders and their reaction loads.
  • Drives, controls, and tuning: pump motor control, valve drivers, exhaust and dump valves, and pressure, level, and temperature permissives.
  • Monitoring: filter differential pressure, fluid temperature, accumulator precharge, and pressure trends.

Each item can be written into the purchase specification by name, in line with the purchaser-supplier agreement that Carlin says the standards stress. UTEC Industrial stress-relieves and machines the welded frames, builds the UL 508A panels, and runs factory acceptance testing and on-site commissioning for the machines it builds (Carlin J 2017; ISO 4413:2010; ISO 4414:2010).

Related Articles

References​

  • ISO 4413:2010: Hydraulic fluid power — General rules and safety requirements for systems and their components. International Organization for Standardization, 2010.
  • ISO 4414:2010: Pneumatic fluid power — General rules and safety requirements for systems and their components. International Organization for Standardization, 2010.
  • ISO 13849-1:2023: Safety of machinery — Safety-related parts of control systems — Part 1: General principles for design. International Organization for Standardization, 2023.
  • ISO 12100:2010: Safety of machinery — General principles for design — Risk assessment and risk reduction. ISO, 2010.
  • ISO 14118:2017: Safety of machinery — Prevention of unexpected start-up. International Organization for Standardization, 2017.
  • ISO 4406:2021: Hydraulic fluid power — Fluids — Method for coding the level of contamination by solid particles. International Organization for Standardization, 2021.
  • ISO 8573-1:2010: Compressed air — Part 1: Contaminants and purity classes. International Organization for Standardization, 2010.
  • Carlin J (2017). "ISO Standards for Hydraulic Systems and Pneumatic Systems." Fluid Power Journal, February 6, 2017.
  • Hauke M, Schaefer M, Apfeld R, et al. Functional Safety of Machine Controls – Application of EN ISO 13849 (IFA Report 2/2017e). Deutsche Gesetzliche Unfallversicherung (DGUV), 2019.
  • Hauke M, Bömer T, Werner C, et al. Funktionale Sicherheit von Maschinensteuerungen – Anwendung der DIN EN ISO 13849 (IFA Report 1/2025). Deutsche Gesetzliche Unfallversicherung (DGUV), 2025. [In German.]
  • Hauke, M., Bömer, T., Büllesbach, K.-H. Fourth edition of EN ISO 13849-1: Most important new features in 2023 at a glance. German Social Accident Insurance (DGUV), 2023.
  • Bosch Rexroth AG. Pressure Relief Valve, Direct Operated, Type DBD (Data sheet RE 25402, edition 2021-08). Bosch Rexroth AG, 2021.
  • Bosch Rexroth Oil Control S.p.A. Reliability Coefficients MTTFD for Functional Safety According to ISO 13849: MTTFD Values for Compact Hydraulics (RE 18350-51/04.25). Bosch Rexroth, 2025.
  • HYDAC Technology GmbH. Safety and Shut-off Block SAF/DSV (brochure EN 3551.25/05.24). HYDAC, 2024.
  • SMC Corporation. Instruction Manual: Safety Exhaust Valve, Series VPX400 (Doc. no. VPX400-TF224-035EN). SMC Corporation, 2024.
  • Festo SE & Co. KG. General Operating Conditions: Conditions for Using, Storing and Transporting Festo Products (2026/01). Festo, 2026.
  • Sun Hydraulics Pub. 999-901-287: Counterbalance and Pilot-to-Open Check Cartridges: Design Concepts, Features, and Applications. Sun Hydraulics, 2023.
  • OSHA Standard Interpretation: Energy Isolation Device Requirements (pneumatic actuated fail-closed valves as energy isolating devices). Occupational Safety and Health Administration, 2021.
  • OSHA 29 CFR 1910.147-1989: The Control of Hazardous Energy (Lockout/Tagout). Occupational Safety and Health Administration, 1989.
  • National Fluid Power Association (2024): Find a Standard. National Fluid Power Association, 2024.
  • NFPA/T3.4.7 R2-2000 (R2024): Accumulator — Pressure rating supplement to NFPA/T2.6.1 R2-2000 — Method for verifying the fatigue and establishing the burst pressure ratings of the pressure containing envelope of a metal fluid power accumulator. National Fluid Power Association, 2024.

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