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MTTFd
Mean Time to Dangerous Failure. In a safety system MTTFD is the portion of failure modes that can lead to failures that may result in hazards to personnel, environment or equipment. MTTFD is critical to the determination of the performance level of a safety system. ISO 13849 defines three levels of MTTFD: ISO 13849 prescribes three methods to determine the MTTFD of a safety channel: # use the manufacturer's failure data; # use the methods prescribed in Annexes C and D of ISO 13849-1 # use 10 years (i.e. assume the channel has low integrity) Mean Time to Failure (MTTF) is assumed constant during the useful life period of a component. The MTTF can be calculated according to: : \text = \fracours\! where λ is the failure rate for the component. The relationship between MTBF and MTTF is expressed as: : \text = MTTF + MTTR \! where MTTR is the mean time to repair Mean time to repair (MTTR) is a basic measure of the maintainability of repairable items. It repres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MTTF
Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a mechanical or electronic system during normal system operation. MTBF can be calculated as the arithmetic mean (average) time between failures of a system. The term is used for repairable systems while mean time to failure (MTTF) denotes the expected time to failure for a non-repairable system. The definition of MTBF depends on the definition of what is considered a failure. For complex, repairable systems, failures are considered to be those out of design conditions which place the system out of service and into a state for repair. Failures which occur that can be left or maintained in an unrepaired condition, and do not place the system out of service, are not considered failures under this definition. In addition, units that are taken down for routine scheduled maintenance or inventory control are not considered within the definition of failure. The higher the MTBF, the longer a syste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MTBF
Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a mechanical or electronic system during normal system operation. MTBF can be calculated as the arithmetic mean (average) time between failures of a system. The term is used for repairable systems while mean time to failure (MTTF) denotes the expected time to failure for a non-repairable system. The definition of MTBF depends on the definition of what is considered a failure. For complex, repairable systems, failures are considered to be those out of design conditions which place the system out of service and into a state for repair. Failures which occur that can be left or maintained in an unrepaired condition, and do not place the system out of service, are not considered failures under this definition. In addition, units that are taken down for routine scheduled maintenance or inventory control are not considered within the definition of failure. The higher the MTBF, the longer a syste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO 13849
ISO 13849 is a safety standard which applies to parts of machinery control systems that are assigned to providing safety functions (called safety-related parts of a control system). The standard is one of a group of sector-specific functional safety standards that were created to tailor the generic system reliability approaches, e.g., IEC 61508, MIL-HDBK-217, MIL-HDBK-338, to the needs of a particular sector. ISO 13849 is simplified for use in the machinery sector. The standard has two parts: * ISO 13849-1, Part 1: General principles for design, provides safety requirements and guidance on the principles of design and integration of safety-related parts of control systems (hardware or software). * ISO 13849-2, Part 2: Validation, specifies the procedures to be followed for validating by analysis or tests, the safety functions of the system, the category achieved and the performance level achieved. ISO 13849 is designed for use in machinery with high to continuous demand rates. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mean Time To Repair
Mean time to repair (MTTR) is a basic measure of the maintainability of repairable items. It represents the average time required to repair a failed component or device. Expressed mathematically, it is the total corrective maintenance time for failures divided by the total number of corrective maintenance actions for failures during a given period of time. It generally does not include lead time for parts not readily available or other Administrative or Logistic Downtime (ALDT). In fault-tolerant design, MTTR is usually considered to also include the time the fault is latent (the time from when the failure occurs until it is detected). If a latent fault goes undetected until an independent failure occurs, the system may not be able to recover. MTTR is often part of a maintenance contract, where a system whose MTTR is 24 hours is generally more valuable than for one of 7 days if mean time between failures is equal, because its Operational Availability is higher. However, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO Standards
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Article 3 of the ISO Statutes. ISO was founded on 23 February 1947, and (as of November 2022) it has published over 24,500 international standards covering almost all aspects of technology and manufacturing. It has 809 Technical committees and sub committees to take care of standards development. The organization develops and publishes standardization in all technical and nontechnical fields other than electrical and electronic engineering, which is handled by the IEC.Editors of Encyclopedia Britannica. 3 June 2021.International Organization for Standardization" ''Encyclopedia Britannica''. Retrieved 2022-04-26. It is headquartered in Geneva, Switzerland, and works in 167 countries . The three official languages of the ISO are English, Fre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safety Codes
S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: ''Safety advice concerning dangerous substances and preparations''. The list was consolidated and republished iDirective 2001/59/EC where translations into other EU languages may be found. The list was subsequently updated and republished iDirective 2006/102/EC where translations to additional European languages were added. These safety phrases are used internationally and not just in Europe, and there is an ongoing effort towards complete international harmonization. ''(Note: missing S-number combinations indicate phrases that were deleted or replaced by another phrase.)'' Safety phrases See also * List of R-phrases * GHS precautionary statements * GHS hazard statements * Material safety data sheet A safety data sheet (SDS), material safety data sheet (MSDS), or product safety data sheet (PSDS) is a document that lists information relating to occupational safety and health for the use of various ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reliability Analysis
Reliability, reliable, or unreliable may refer to: Science, technology, and mathematics Computing * Data reliability (other), a property of some disk arrays in computer storage * High availability * Reliability (computer networking), a category used to describe protocols * Reliability (semiconductor), outline of semiconductor device reliability drivers Other uses in science, technology, and mathematics * Reliability (statistics), the overall consistency of a measure * Reliability engineering, concerned with the ability of a system or component to perform its required functions under stated conditions for a specified time ** High reliability is informally reported in " nines" ** Human reliability in engineered systems * Reliability theory, as a theoretical concept, to explain biological aging and species longevity Other uses * Reliabilism, in philosophy and epistemology. * Unreliable narrator An unreliable narrator is a narrator whose credibility is compromised. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
