Reliability coefficients MTTF D for functional safety according to ISO MTTF D values for cartridge valves

Transcription

1 Reliability coefficients MTTF D for functional safety according to ISO MTTF D values for cartridge valves RE Edition: Replaces: Contents Calculation of MTTF D values according to ISO : Compliance with safety principles, application notes 2 Product-specific additional information on MTTF D 3 Pressure-relief valves 4 Proportional pressure relief valves 4 Pressure reducing valves 4 Proportional pressure reducing valves 4 Pressure cut-off valves 5 Check valves 5 Directional seat valves 5 Directional spool valves 5 Proportional directional spool valves 5 Flow control valves 6 Feed valves 6 Shuttle valves 6 Logic valves 6 RE 90294/ , Bosch Rexroth AG

2 2 Reliability coefficients MTTF D values for cartridge valves Calculation of MTTFD values according to ISO :20151) Calculation of MTTF D values according to ISO :2015 1) The reliability coefficients MTTF D (mean time to dangerous failure) of components are used to calculate the probability of a potentially dangerous failure per hour (PFH d ) of a machine or system and to keep this to an acceptable level. For hydraulic components, the standard ISO :2015 stipulates an MTTF D value of 150 years for more than 1 million switching cycles per year, assuming that fundamental and proven safety principles are applied. Requirements for hydraulic vales employed in safety-related parts of control systems include: Automatic reset to basic settings in the event of a power failure Reliable maintenance of the basic settings Sufficient overlap of spool valves in the basic setting Hydraulic components which are not compliant with the relevant safety principles are not suitable for application in safety-related parts of control systems. Bosch Rexroth has carefully tested its products with respect to all relevant fundamental and proven safety principles in accordance with a method recognized by the Institute for Occupational Safety of the German Statutory Accident Insurance Association (IFA). Compliance with safety principles, application notes The Rexroth products listed below are generally suitable for use in safety-related parts of a control system according to ISO :2015. These products are compliant with ISO :2012, in particular with the fundamental safety principles proven safety principles. Use the following parameters for the product for evaluating and configuring the reliability of the control systems: MTTF D = see table from page 3 T M = 20 years (maximum duration of use according to ISO :2015) When using these, please ensure compliance with the following application notes! Application notes The further fundamental and proven safety principles according to ISO :2012 which are needed for implementing and operating the products are also to be fulfilled. For the operation and handling of the products, the system specifications stipulated in the data sheet and instruction manual must be observed. Only use the hydraulic fluids specified in the data sheets and maintain the cleanliness of the hydraulic fluid over the entire period of use. Spool seizures may occur after a prolonged period in which the switching spool valves are not used. Our advice is therefore to regularly switch or actuate the system at reasonable periods. If the product is employed for safety-related structures with higher categories (2 to 4) according to ISO :2015, Section 6, take into account the requirements stipulated there (e.g. CCF, DC, PL r, software, system errors). According to ISO :2015, the maximum period of use, observing the cleanliness of the hydraulic fluid according to ISO 4406:1999 T M = 20 years. In the interest of preventive maintenance, it is advisable to exchange the components before this maximum period of use has expired. 2 million switching cycles per valve is generally assumed for use in mobile applications. Other parameters can be found in the valve data sheet. If the maximum number of switching cycles is exceeded within the period of use, then shorter exchange intervals are to be specified accordingly. 1) MTTF D is a static characteristic that was defined according to the requirements of DIN EN ISO for hydraulic components. It does not specify a guaranteed service life or downtime-free time. Bosch Rexroth AG, RE 90294/

3 MTTF D values for cartridge valves Reliability coefficients Product-specific additional information on MTTFD 3 Product-specific additional information on MTTF D Cartridge valves from Bosch Rexroth also have the following MTTF D value specified during active operation. In order to realize the necessary safety function in the machine, further measures have to be realized by the machine manufacturer (e.g. use of a suitable control unit or sensor). The machine manufacturer bears the responsibility for the safety of the machine, including the correct design and evaluation of the control systems employed in the safety functions. He is thus responsible for ensuring compliance with normative and statutory requirements in the countries concerned. System reliability / life cycle costs (TCO) Because the MTTF D values only take account of the safetyrelated parts of a component, these coefficients are not suitable for evaluating the reliability of a system or the life cycle costs (TCO = Total Cost of Ownership). If necessary, please consult your contact person at Bosch Rexroth. Formulas MTTF D = n op = Key MTTF D B10 D n op d op h op t cycle B10 D 0.1 n op d op h op 3600 s/h t cycle Mean time to failure dangerous Number of cycles until 10 % of the units have failed dangerous Mean number of annual operation cycles Mean number of operation days per year Mean number of operation hours per day Cycle time [s/cycle] RE 90294/ , Bosch Rexroth AG

4 4 Reliability coefficients MTTF D values for cartridge valves Pressure-relief valves Pressure-relief valves DB 6 / no DB no DBD.4K no DBD.4K SO D 150 no DBD.K no MHDBB, MHDBL no MHDBD no MHDBL no MHDBN no MHDBN.Y no MHDBV no MHDBV.Y no Proportional pressure relief valves KBVS.3A no KBVS.3B no KBVS.1A no KBVS.1B no KBVS.2DB no KBPS.8A no KBPS.8B no Pressure reducing valves DR no DR no KRD no Proportional pressure reducing valves Bosch Rexroth AG, RE 90294/ FTDRE no FTDRE no MHDRE no MHDRE no DRE 05 SK no MHDRE 06 SK no MHDRE 06 SK no KTVS no 2) The MTTF D values are valid for the type named in the relevant data sheet. Other MTTF D values for non-listed products and special versions available on request!

5 MTTF D values for cartridge valves Reliability coefficients Pressure cut-off valves 5 Pressure cut-off valves KAV no Check valves M-SR no Directional seat valves KSDE.0 (2/2) no KSDE.1 (2/2) no KSDE.1 (3/2) no KSDE.8 (2/2) no Directional spool valves KKDE.1/HP (2/2) no KKDE.1/HP (3/2) no KKDE.1/HP (4/2) no KKDE.8/SP (2/2) no KKDE.8/SP (3/2) no KKDE.8/HP (2/2) no KKDE.8/HP (3/2) no FTWE no FTWE no Proportional directional spool valves KKDS no KKDS no KUDS no 2) The MTTF D values are valid for the type named in the relevant data sheet. Other MTTF D values for non-listed products and special versions available on request! RE 90294/ , Bosch Rexroth AG

6 6 Reliability coefficients MTTF D values for cartridge valves Flow control valves Flow control valves MH2FR no 2FRM no KFD on request 150 no Feed valves MHSV no Shuttle valves MHSU no Logic valves MH2DAD no 2) The MTTF D values are valid for the type named in the relevant data sheet. Other MTTF D values for non-listed products and special versions available on request! Bosch Rexroth AG Zum Eisengießer Lohr am Main, Germany Tel info.ma@boschrexroth.de Bosch Rexroth AG All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights. The data specified within only serves to describe the product. No statements concerning a certain condition or suitability for a certain application can be derived from our information. The information given does not release the user from the obligation of own judgment and verification. It must be remembered that our products are subject to a natural process of wear and aging. Bosch Rexroth AG, RE 90294/