Frequently Asked Questions

exSILentia

FAQs for exSILentia


Further Articles

  1. After receiving the online access to exSILentia version 4 "standard". I can not access the LOPA tab as it is greyed out. Is this correct as LOPAX is in the standard tool kit.  
  2. An exida FMEDA report provides two sets of failures for a remote seal - Normal Service and Severe Service. Please can you advise when the "severe service" mode is to be used. It is understood that the remote seals will be designed "fit for purpose" for sp  
  3. As per IEC 61508 part 2 (ed. 2) clause 7.4.9.4-J, diagnostics is considered in the realization of the SFF. As per IEC 61508 part 2 (ed.2) clause 7.4.5.4, diagnostic test interval shall be such that the sum of diagnostic test interval and the time to to pe  
  4. Can we print the failure rates or certificates from the SERH?​ If not, how we can then justify then the data used? In v.3 we could attach the SERH data used in the projects as a .pdf.  
  5. Can you explain the difference between SRS and Design SRS?  
  6. Can you explain what does it mean by Digital Out Low Channel and Digital Out High Channel? Is it related with the power of the logic solver?  
  7. Can you please advise if / how Partial valve stroke testing can be applied to valves set as diverse valves.  
  8. Can you please advise if version 2 works in Windows 10?  
  9. Can you please confirm how exactly Annunciation Failures are accounted for? In my example, the 30 FITs for FAu are not part of the Fail Low, Fail High, Fail Detected, Dangerous Detected, Dangerous Undetected, Safe Detected, Safe Undetected or Residual. Wh  
  10. Can you please help further clarify “ Online Maintenance”. What does it mean in terms of work to be done on a subsystem (e.g. valve)?​  
  11. Can you please provide a detailed description of how partial stroke testing is used in the calculation of SFF. In particular, what is the basis for ignoring PVST(manual) in the calculation of SFF but taking credit for PVST(automatic) at the same interval?  
  12. Could you explain why increasing the beta factor for 2oo2 will reduce the PFDavg (or increase the RRF) in exSILentia? This is contrary to common understanding. What is the common value used for such architecture?​  
  13. Could you please advise whether the SERH generic data for Skotch Yoke Pneumatic Actuators lambda du of 350 FITs can be considered conservative. What is the basis for the 350 FITs? There are not many of this actuator type in the SERH list to compare to.  
  14. Could you please clarify what the difference between Online/Offline options provided for Sensor and Final Element in exSILentia, in regards to Proof Test Interval. There is no such option provided for logic solver part! In case of choosing "Offline" optio  
  15. Could you please confirm if the exSILentia software is verified / certified by an external body ?  
  16. Could you please confirm the following with regards to verifying the SIL for a Temperature Trip. Can the sensing element (such as the Thermocouple, RTD etc.) be considered as a "passive" from a SIF loop and be ignored from the PFDavg. calculations. This w  
  17. Could you please let me know the more detailed definition of "High Stress" & "Low Stress" ?  
  18. Does the user manual provide enough guidance as to how to handle the exSILentia software without training?  
  19. During a SIL verification process a query was raised as to whether the mission time in the software can be equal to the plant turnaround, or should it be equal to the time from plant start-up to the replacement or refurbishment to as-new condition of the  
  20. During our SIL verification assessments we came across a case where the initiator of a SIF is a push button (pressed by an experienced operator) which through a SIL 3 PES closes two SIL 2 MOVs in 1oo2 architecture. My question is whether such a SIF could  
  21. For a certain valve, 2 different proof tests with the same valve are required, with a full function test once every 4 years. However the valve is sometimes used during normal operation. This usage during normal operation can be seen as a partial test that  
  22. How can I include two logic solvers (F&G and ESD) in order to verify an entire F&G circuit.?  
  23. How can I make it easier to open windows for SRS? There seems to be a tiny sliver on the right with a > symbol  
  24. How can we do the calculations for a motor with a HP higher tan 250HP? Which final element from your database shall we use? Or do you have a typical lambda DU / lambda SU for that?  
  25. How can you manually make a selection between route 1H and 2H if you have selected IEC61508​?  
  26. How do I perform an "Exclude these beta selections from the report" option from the Beta Factor Estimator to the parameters that can be changed en masse for SILver?  
  27. How do you configure the following logic for the Final Element Part of exSILentia V4? Valve 1 OR (Valve 2 AND Valve 3)?  
  28. How does demand rate set to "based on demand rate" change the PFH calculation? For SIFs using sensors, logic solver, and final elements with HFT>0 (with redundancy), how will the high demand calculation for PFH account for changes in the manual proof tes  
  29. How does the software calculate a SIF? Does exSILentia 4 use the RBD, simple model, solution tree or another model?  
  30. How should I model "close riser ESD valve (1oo1) and either well SSV or SDV (1oo2) of 9 wells (9oo9)" using exSILentia? The configuration is written as follows: Close 2oo2 [1oo1 UZV & 9oo9 (1oo2 SSV or SDV)]​  
  31. How to I get a non-empty SIF SRS segment?  
  32. How would I be able to model 2 solenoids in series with 1 valve for the final element. I have a 1oo2 configuration for the solenoids, but only a single valve.​  
  33. I am having trouble modelling the final control element of a SIF loop, having a 1oo2 (with 1oo1, and 4oo4) voting logic. The issue is that in the 4oo4 final control element leg, each component is having different failure rates, therefore I cannot select a  
  34. I am wanting to enter Vendor supplied PFDavg and MTTFS values for a simple User defined logic solver, using the calculation tool. However when I use the button in the upper right hand corner of the dialog to convert the PFD and MTTFS to LambdaDU and Lambd  
  35. I am wondering what is the relation between process connection (remote seal, impulse line-plugging unlikely etc. ) specified on an instrument and architectural constraints please? Specifying process connection impacts the SIL achieved due to architectural  
  36. I can’t find my gap where I get an RRF of 237 but yet don’t even achieve SIL 1 for the a SIF. Can you help explain this?  
  37. I found that the process connection for temperature transmitter is mandatory information for SIL verification but another transmitters are not. Is there is special reason or technical issue for this?  
  38. I have a 1oo1 pressure sensor A. Every year (during the periodic proof test) I can compare this sensor A with another sensor B, which is located further inline. By manually aligning (with the aid of valves) both sensors, I'm capable of doing a compare bet  
  39. I have a 1oo2 of 2 pressure sensors (A and B). Since both sensors are safety relevant, they are connected to the safety PLC. Can I also claim Ext. Comp. for this system? If so, how much coverage can be claimed for it?  
  40. I have a problem trying to create a user defined logic solver. In version 3 you could user define a logic solver so you could use simple devices like a trip amplifier or relay. In Version 4 it looks like I can only select a device that is in the database  
  41. I have a question about MTTR time used in SIL Verification. Is this for the complete mission time duration?  
  42. I have a question about the Application Test Method section of the SIF parameters section in the SILver design tool. Can you provide me with a description of the purpose of this section? I understand that I am able to choose between the IEC61508:2000 or I  
  43. I have a question about the EU Low/EU High sections in the tag section of a sensor group. Is this referring to the signal low/high (2/22 mA?) that will trigger a diagnostic trip for the SIF?  
  44. I have a question about the systematic capability option for equipment in exSILentia. Can this systematic capability parameter can be used for a generic element? If it indeed can be used, how can be set this systematic capability value for a generic eleme  
  45. I have a question on the voting option for final element groups. Would you please explain the meaning and structure of 2oo4 [2oo(1oo2)]?  
  46. I have a question regarding the correct way to simulate voting logic. I don’t understand how different PFD values are calculated if the same voting logic (e.g. 2oo3) are considered within different channels or one single channel.  
  47. I have a question regarding the Diagnostic Coverage Factor; it used to be possible to enter this value in the software for each device - has this feature been removed?​  
  48. I have a sensor which consists of a level transmitter and a Pepperl-Fuchs KFD2-SR2-Ex*. I have a 1oo2 configuration in sensors but the option "External comparison" is not available as it says "PLC Detection configuration is only available for analog conne  
  49. I have a SIF that uses a Vegaswing 61/63. This model contains a relay contact which is connected to the triconex tricon DI (discrete input) module. However, exSILentia is showing an AI (analog input) channel being used on the triconex tricon. Shouldn't t  
  50. I have a system where the logic solver is a set of relays. Can exSILentia be used for a system like this? When I configure the inputs there as 2oo3 there is no place to put the Relay that the three inputs are connecting to. Then the master relay has seven  
  51. I have an application with 11 risers from sub-sea oil wells each having dual isolation valves in series, voted 1oo2. I have modelled the scenario assuming four risers and I need help on how to configure a voted group of 11oo11 where each leg has 1oo2 vote  
  52. I have defined a wire as a logic solver (without channels). However the PFDavg for the Logic solver is calculated as 0.0E+0 and the SIF PFD average does not calculate. ​  
  53. I have followed the instruction to create a user defined logic solver but I still have issues that I can’t a simple device such as a trip amplifier because I can’t define any data for the channels for a device such as this. It appears that I have to also  
  54. I have imported a Ver.3 file into Ver.4 of exSILentia.When I was working in Ver.3 I copied a SIF, BD11-02C and made it BD11-02D. In Ver. 4 I have found that when I edit the Sensor Part Name in BD11-02C it also changes it in BD11-02D. What is going on?  
  55. I have just upgraded to 4.0 and noticed SILver sets my target RRF to 1. Please how do I set the target RRF in version 4.0 using SILver alone (without completing LOPA/Select etc.), such that the target RRF is reflected in the auto generated Detailed SILver  
  56. I have some further questions regarding the use of solenoid valves for pneumatic valve actuation within the SilVer software: 1. Could you please confirm that the correct location to specify the solenoid is in the Final Element Interface? 2. Could you plea  
  57. I installed the latest version of exSILentia 4, but I can't open my original project created in version 3. How can I convert the version 3 project file to be readable from version 4?​  
  58. I just downloaded the new exSILentia V4 and although I can see the CyberPHAx and CyberSL listed in the Modules window under tools, I cannot find how to access the actual tools and I do not see them on the black bar headings in the second line of the exSIL  
  59. I received a "XXYYZZ" Manufacturers Declaration on "XXYYZZ" actuators that has an exida report attached. I haven't been able to find the report on your website. The data in is the exSILentia program but doesn't seem to be certified. Is the data expired  
  60. I requested the SILVER update, and then tried the status button, which said I had not submitted a request.  
  61. I want to create a user defined sensor/final element, however, the failure rate entry window is different from version 3. I want to understand the meaning of Prc [%] field. Is this Route1H SFF [%]?​  
  62. I would like to ask how MTTFS is calculated as I am not able to achieve the same results as the software. The failure rates of the sensor are the following: Safe Detected: 1.44E-06 | Safe Undetected: 1.44E-06 | Dangerous Detected: 1.41E-06 | Danger  
  63. I would like to know the main differences between selecting the Application Test Mode of IEC 61508:2000 and the Appplication Test Mode of IEC 61508:2010.​  
  64. I would like to know which tables from 61511:2016 are considered when using this option for architectural constraints in the SIL verification parameters?  
  65. I would like to model 5oo5 final element groups - a prompt is saying to "adjust" the limit of 4 final element groups in "Project Configuration" - however, this parameter is not found in "Project Configuration" - Silver Project Parameters. Is it possible t  
  66. I would like to model a 1oo2 architecture identical to the one found in "Final Elements in Safety Instrumented Systems" pg.210-212. Does exSILentia offer a tool to create an event tree for this type of modelling?​  
  67. I would like to model a final element with the configuration of two 1oo2 interface modules and one 1oo1 final element, with specific manufacturer failure rates - how do I do this?  
  68. I would like to obtain the exSILentia reports with the decimals represented with dot instead of comma (2.5 instead of 2,5). Where do I configure that?​  
  69. I'd like to select "none" on the process connection on a temperature transmitter, but this option is not available. Why do I have to select the thermocouple or -2/3- wired..something when it comes to the temperature transmitter alone?  
  70. I'm attempting to use "check for updates" to download Silver version 4 and getting error "The server name or address could not be resolved".  
  71. I'm getting an error message 'xxxx' is not a valid value for this property. Valid values are from Int32.MinValue through Int32.MaxValue.  
  72. I'm unable to open exSILentia 3 files using exSILentia 4 - Conversion Failed. Unable to access exida Equipment Database  
  73. I'm using SILver to verify the SIL level of some existing installations. There's a lot of old instruments so when there's no other option, I have to use the generic data. The PFDavg and architectural constraints are good, but logically the systematic capa  
  74. I'm working on a project where the logic solver is a SIL 2 Allen Bradley ControlLogix system with redundant processors and redundant (1oo2) IO. I do not see any Allen Bradley or Rockwell Automation logic solvers in the equipment database. Nor do I see any  
  75. I've been reviewing some SIF verification calculations in exSILentia and I was hoping you could advise on how the software determines the failure rate from manually inputted failure rate data?  
  76. If "frozen output" failures are classified as DU, and failures as "drift failure" are classified as 50%DU and 50%SU, then DU failure rate should always be higher than SU failure rate. But considering,for example, the Yokogawa EJA Serie E transmitter I see  
  77. If a sensor is put on a soft maintenance bypass, would that be considered as an online maintenance?  
  78. If maintenance is carried out during the time while the subsystem (e.g. valve) is in service, would that time be captured in verification calculations using MTTR?  
  79. If the Partial Stroke test is done in "Manual" mode, the architectural constraint limits the SIL level to "1", whereas - If the Partial Stroke test is done in "Automatic" mode, the architectural constraint meets the SIL level "2" requirement. Could you pl  
  80. If the time used for proof test for the SIF subsystems has any connection with MTTR, is the MTTR counted independent of the time used for Proof Test Interval? ​  
  81. In a report with an On/Off valve with the accessories MTL-4521, ASCO SOV, Emerson Actuator, and OMS Ball Valve, all the accessories are individually meeting SFF of above 70% but the overall SFF is coming to be 54%. Can you explain this please?  
  82. In exSILentia the failure rates that are used from the SERH database are the same for low demand and high demand applications. Is there anything that needs to be considered, associated with the input failure rates to exSILentia when in high demand compare  
  83. In low demand mode, hardware constraint verification works fine in exSILentia. May I know why when High Demand or Continuous Demand Mode is selected, hardware constraint verification disappears in exSILentia?​  
  84. In order to meet Target SIL 3, we have to apply PVST (Automatic; Interval 3 Months; Coverage 80%) for both valve groups. This means if I input ESD as an interface module for Valve 2, it looks like ESD is also diagnosed by PVST; (Actually, ESD is not relat  
  85. In our project, there is a Local Panel from which after every 3 months operator will press the Start PST push button and it will execute the PST automatically thereafter. In such a scenario​ can we consider PST to be automatic and take credit for it or do  
  86. In our setup, for the valve PST, smart positioners have been installed. A test is initiated from DCS Station by operator. The test results are automatically captured in the AMS (Asset Management System). Could you please help confirm if the setup in plac  
  87. In regards to MTTR, does the value refers to the complete duration while the SIF is in service i.e. the testing of a subsystem as well as any other maintenance being carried out on a subsystem?  
  88. In the new version of the software, we've had a problem related to the beta factor in the Final Element. Usually, when the Beta factor is increased, the PFD is increased too. But in this version, it happened the other way around. It only happens in the fi  
  89. In version 4 is it possible to update parameters like in version 3? In version V4 where I can find the Unit MTTFS?​  
  90. Is it possible to select the HFT constraints routes, subsystem wise, instead of applying it only to the whole SIF? i.e. Route 2H-61508 for “S”, Route 1H-61508 for “Logic Solver” and clause 11.4.5 IEC61511 2nd edition for “Final Element”​?  
  91. Is it possible to set up 2 (or more) different proof tests at different frequencies each with different %age coverages for 1 SIF?  
  92. Is there a way to add conditional modifiers (such as probability of ignition, occupancy, etc) and/or time at risk to the LOPA assessment​?​  
  93. I´m looking at transmitters failure rates of SERH database and I see a category called Fail Dangerous Undetected. But to classify a failure as safe or dangerous it is necessary to know if the transmitter action trips on high or low value. How can you know  
  94. I´m working with ExSilentia and I installed a "Generic SIL 3 certified PLC" from the SERH database with a poof test interval of 7 years. The contribution to the PFDAv informed by the software is 1.06E-4 (please see the attached screen capture). However in  
  95. I’m modelling a SIF which is an interlock system. This interlock system is based on the sensor parts and stops at the Logic part. The Final element is not considered. For such a SIF, I modelled it without the Final Element and the software does not seem  
  96. I’ve copied the parameters from a supplier in SILver, but I don’t understand why the PFDavg value calculated in SILver (3.10E-02) is different to the value in the manufacture datasheet (8.76E-04) for Sensor TMT82 of Endress+Hause for 5 years? 1oo1, theref  
  97. Occasionally I experience performance issues when using the online version, with navigation between menus being slow or even frozen.  
  98. Please advise how to add external comparison to a sensor group.  
  99. Please advise silent installation procedure or addition code / methodology for silent software installation.  
  100. Please can you advise how the safe failures are calculated for a final element with partial stroke testing?  
  101. Please could you let me know the save location for the user specific LOPA database. I've set up exSILentia 4 on my PC with our company LOPA data but when I move to another PC the user specific data is missing. The help files say this is embedded in the pr  
  102. The Achieved SIL box is not updating. An example is where the SIL 2 has been calculated/achieved but the SIL Achieved box shows 0. Not sure if this is an error I am making or a software problem. Please advise.​  
  103. The calculation of PFD shows a discrepancy between the exSILentia and ISA formulas. Would you be kind enough to share the formula used in exSILentia so we may compare and note what are the differences and evaluate ISA formula accordingly.  
  104. The drop down menu for choosing a logic solver does not include the HIMA SELLA HiQuad H51q, is there a particular reason for this, and is it possible to input the information for this system manually?  
  105. The exida LOPA database did not install on the user's system. Can you provide instructions/download for the database?  
  106. The exSILentia database includes failure rates for Industrial PLC that has the remark that the data reflects a high-end general purpose PLC like ControlLogix. The Allen Bradley safety reference manual on Using ControlLogix in SIL 2 applications states tha  
  107. The SERH data for a Fisher Control DVC6200 SIS DETT lists the device type as Type A, which means it should be a simple mechanical non programmable device. However as the DVC6200 SIS has a micro controller cum processor built in which can be programmed for  
  108. This refers to the Generic 2/3 Wire RTD Configurations in exSILentia. We find that the Generic 2/3 wire RTD close coupled, Low stress lamda du = 173 and RTD Extension wire, Low stress lamda du =95. This data points in the direction that close coupled is b  
  109. We are looking at modelling a SIF that is activated upon low motor current to furnace fans. Would you be able to advise what sensors are available in exSILentia for measuring motor current, and would be suitable for this? We also have a SIF that trips the  
  110. We are performing a SIL Verification for an existing plant (plant has 20 years). What Mission Time do we need to choose? If it was a new plant, we would usually take 25 years, and the PDF calculations would start "from now". How can we consider that we ar  
  111. We have 2 related Logic Solvers in one SIF. When the Steam Turbine Speed is High High, our SIF closes steam line 2 valves to protect the compressor. One valve is closed via PLC 1 (Invensys Trident, 2oo3 TMR) and the other is closed via PLC 2 (Honeywell SM  
  112. We have a 4oo4 final element. We realised that when we increase the beta factor the probability of failure on demand decreases. How is it technically possible? Theoretically, when the the beta (common failure mode) is increased, the PFD should decrease?​  
  113. We have a conceptual design where we would like to model 9 “output groups”. For each of the 9 output groups, we would like to include a 1oo2 valve assembly (identical), i.e., redundant valve assemblies (including 1oo2 solenoid valves on each valve, the ac  
  114. We have a number of applications providing dual logic solver outputs, via 2 separate solenoid operated valves & 2 separate pneumatic booster relays, to a single air actuated valves. How do we model this?​  
  115. We have a pressure transmitter with an SFF> 90% that we use in a SIL 2 with an HFT of 0 (see table 2 and 3 IEC61508-2). Then a Intrinsic Safety Isolated Barrier is also included in this loop (P&F). When we enter these 2 devices into exSILentia, the SFF de  
  116. We have a project where, for the Safety Functions with Voted Sensors, there are cases where instruments have individual taps for process connection, while in other cases, process connection to the sensors is through a common tap. With that being the case,  
  117. We have a project with a total of 10 SIFs that have a total of 20 different input and 20 different outputs. Question: when inserting (counting) the numbers of IO in the logic solver selection at the individual SIF - must we insert the total number (20+20)  
  118. We have a question on how exSILentia apply beta factor to diverse redundant configuration. If dangerous undetected failure of isolation valve (e.g., XV) is higher than that of CV (control valve), which of the following PFDs of CCF is the closest to the PF  
  119. We have a safety function (Permissive) that does not have a final element. How can we model such a function in exSILentia? Apparently without Final Element, exSILentia results "0" as the PFDavg for the function (permissive).  
  120. We have a SIF with 5 streams (each stream with 1oo2 shutoff valves) that trips all of the valves on these 5 streams in case of an event. How do we configure this SIF voting?​  
  121. We have a SIF with the dual temperature elements (RTD) and one temperature transmitter with hot backup function. Can we use a separate SIF to get the failure rates of 1oo2 voting of sensor parts for dual RTD and fill this calculated failure rates into the  
  122. We have a situation where a proof test coverage of 95% on the final element part of a particular SIF is being claimed. The final element part consist of a solenoid valve and separate actuator and valve. Tight shut off is not necessary. Is this credible? H  
  123. We have an issue regarding the IEC 61511 compliance report. We generated 2 reports on different times but with the same data. In the first case we got a SFF value of 80.1 for our final element in a SIF. When we generated a new report the SFF value has bee  
  124. We have one set of 1 Transmitter and 1 IS Isolator. I approached this in 2 different ways. Option 1) transmitter + IS Isolator in Sensor Group 1. Option 2) Transmitter in Sensor Group 1 + IS Isolator in Sensor Group 2. The PFDavg were same between Option  
  125. We need to do the SIL Verification of a safety loop which does not include a PLC but goes from the sensor to the final element through direct cabling (TT which stops a motor). How can we do this?  
  126. We need to simulate a trip which is 3FT in a 2oo3 voting and compensated by pressure and temperature by a PT and TT for each FT. How can we proceed?  
  127. We noticed there is a difference when we use a 1oo2 voting for 2 redundant measurements as a leg, or as a group. exemple 1: TT1 1oo1 1oo2, TT2 1oo1. exemple 2: TT1+TT2 1oo2 1oo1. Which is the correct one? why is it and what is causing the difference in fa  
  128. We recently updated our SERH database and noticed that we have an option to add Rosemount 1199 remote seals into our calculations. They are a SIL 2/3 rated device but drop my PFDavg number by 30 points. I cannot get my numbers anywhere near a SIL-2 calc w  
  129. We use a large amount of remote seals in our plant. I understand the difference between the 2 seal options when looking at DP or Level measurements. However, we use some Rosemount 1199 units strictly on pressure transmitters. How do we determine if we sho  
  130. We would like to create a fault tree, with multiple layers BMS, SIS, BPCS and ESD. Is there a way to do this in exSILentia?  
  131. We would like to perform a Verification with a Full Stroke Test in a valve. It is possible to include this consideration in the Verification.?  
  132. When a colleague or I try to login, we are able to login but then get a blinking screen. We tried both IE and Chrome and got the same result.  
  133. When constructing a SIF consisting of a sensor, trip evaluator/transducer (PR 4116), a safety relay and a valve (no safety PLC), I get different PDF values depending on if I define the PR4116 as an interface to the sensor, compared to if I define it as pa  
  134. When creating new SIL verification calculations it appears I can only select logic solvers from 'EDB' as opposed to adding my own failure rate information.  
  135. When generating the SILlver summary report or detailed report - this is an "error" shown in word viewer -cannot open file. The Silver detailed report does give options to select which SIFs (or all) to report.​  
  136. When I go to C:\Program Files (x86)\exida\exSILentia 4​ (the default install location), I see two files: exida.lopadb and generic.lopadb, but both have the size of 1kB with today's date. I doubt they are not the correct database. For reasons that I do not  
  137. When I logged in first thing today onto my computer I was able to successfully access the software. I then logged off and went to a computer in a meeting room where I had a workshop scheduled and needed to access a screen projector. When I logged into thi  
  138. When I open a PHA file through my coworker's account on my computer the file has no data in it. The PHA and LOPA tabs are not present. When my coworker opens the file through his account on his computer, the file is present with all the data​.  
  139. When I purchase the exSILentia tool is the Safety Equipment Reliability Handbook included or is there extra cost?  
  140. When I switch between the 2000/2010 application test methods and man/auto applications (and PVST) testing, the result changes. I would expect the manual in 2010 to provide the same result as manual/auto in 2000 mode. On the final element, enabling the par  
  141. When installing solenoids, does exSILentia assume 1 x solenoid per actuator & valve? Could a 1oo2 solenoid system for example be installed, or a common solenoid that closes two valves?  
  142. While performing SIL verification for MCC (Motor Control Center) trips e.g. Pumps, Blowers , Compressors, Heaters etc. within the final element group, what is the minimum information that needs to be included? For example, if we have an interposing relay  

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