Activity

  • Non-contacting Radar for Automatic Tank Gauging and Overfill Prevention Systems

    Jim Cahill
    Bulk liquid storage tanks often contain fluids that are hazardous, flammable and/or explosive. These tanks require not only a control system to control levels but and overfill prevention system (OPS) as layer of protection beyond the control system. This basic process control system (BPCS) is commonly referred to as an automatic tank gauging (ATG) system and the OPS is the safety instrumented system (SIS). A Fluid Handling…

  • Understanding Functional Safety Concepts and Final Element Suitability

    Jim Cahill
    Riyaz Ali The world of functional safety has its own tribal language and acronyms, e.g. safety instrumented systems (SISs), safety instrumented functions (SIFs), logic solvers, final elements (FEs), safety integrity level (SIL), probability of failure on demand (PFD), etc. In a Hydrocarbon Engineering article, Keep in the Safety Loop , Emerson’s Riyaz Ali does an excellent job of defining and demystifying these phrases…

  • Approaches to Partial Stroke Testing Safety Valves

    Jim Cahill
    The safety valve within a safety instrumented function (SIF) must be tested regularly to help assure proper operation in the event of a safety demand. Operators usually perform an offline full stroke test during a scheduled shutdown because of the impact of this test on the process. But when a SIF (a.k.a. safety loop) requires more frequent testing, users can perform a partial stroke test (PST) , per the global IEC 61511…

  • Approaches to Partial Stroke Testing Safety Valves

    Jim Cahill
    The safety valve within a safety instrumented function (SIF) must be tested regularly to help assure proper operation in the event of a safety demand. Operators usually perform an offline full stroke test during a scheduled shutdown because of the impact of this test on the process. But when a SIF (a.k.a. safety loop) requires more frequent testing, users can perform a partial stroke test (PST) , per the global IEC 61511…

  • Approaches to Partial Stroke Testing Safety Valves

    Jim Cahill
    The safety valve within a safety instrumented function (SIF) must be tested regularly to help assure proper operation in the event of a safety demand. Operators usually perform an offline full stroke test during a scheduled shutdown because of the impact of this test on the process. But when a SIF (a.k.a. safety loop) requires more frequent testing, users can perform a partial stroke test (PST) , per the global IEC 61511…

  • Safety Instrumented System Cybersecurity Best Practices

    Jim Cahill
    Emerson’s Sergio Diaz and Alexandre Peixoto presented Best Practices for a Cybersecure SIS at the 2019 Emerson Exchange conference. Sergio opened that the goal of this presentation is to provide practical information to maintain a more defendable security posture for safety instrumented systems (SISs) . Like control systems, defense in depth is an important concept for an SIS. It starts at plant level security, work…

  • Security for Safety System Logic Solvers-Physical Key Switches and Software Locks

    Jim Cahill
    Sergio Diaz Author: Sergio Diaz As a product marketing manager for DeltaV safety instrumented systems (SIS) , I have been asked a few times why the key switch on the CHARMs Smart Logic Solver (CSLS) does not control the lock state as is common with many safety controllers. DeltaV CHARMs Smart Logic Solver (CSLS) The next question is, “Why does the user still need to lock the CSLS via software?” The reason is…

  • Reducing Level Detector Proof Testing Complexity

    Jim Cahill
    Each safety instrumented function (SIF) including its sensor, logic solver and final control element must be periodically tested to make sure it will perform as designed in the event of a safety demand. These “proof tests” help to uncover and failure conditions which may have developed since the last proof test or safety demand. A new whitepaper, Reducing the Complexity of Proof-Testing with New Generation Point Level…

  • Reducing Level Detector Proof Testing Complexity

    Jim Cahill
    Each safety instrumented function (SIF) including its sensor, logic solver and final control element must be periodically tested to make sure it will perform as designed in the event of a safety demand. These “proof tests” help to uncover and failure conditions which may have developed since the last proof test or safety demand. A new whitepaper, Reducing the Complexity of Proof-Testing with New Generation Point Level…

  • Reducing Level Detector Proof Testing Complexity

    Jim Cahill
    Each safety instrumented function (SIF) including its sensor, logic solver and final control element must be periodically tested to make sure it will perform as designed in the event of a safety demand. These “proof tests” help to uncover and failure conditions which may have developed since the last proof test or safety demand. A new whitepaper, Reducing the Complexity of Proof-Testing with New Generation Point Level…

  • Reducing Level Detector Proof Testing Complexity

    Jim Cahill
    Each safety instrumented function (SIF) including its sensor, logic solver and final control element must be periodically tested to make sure it will perform as designed in the event of a safety demand. These “proof tests” help to uncover and failure conditions which may have developed since the last proof test or safety demand. A new whitepaper, Reducing the Complexity of Proof-Testing with New Generation Point Level…

  • Cybersecurity Considerations in Safety Instrumented System Architectures

    Jim Cahill
    Sergio Diaz Alexandre Peixoto Safety instrumented systems (SIS), which are designed to take the process to a safe state in trip conditions, come in several architectures with the basic process control system (BPCS). The SIS and BPCS can be totally separate, interfaced or integrated, yet separate. While the debate on which approach is best has been going on for a long time, what are they cybersecurity considerations…

  • Storage Tank Overfill Protection

    Jim Cahill
    Lydia Miller AnnCharlott Enberg Preventing overfill conditions in tanks and vessels is a job for safety instrumented systems across many industries. In a Flow Control article, A Systemic Approach to Storage Tank Overfill Protection , Emerson’s Lydia Miller and AnnCharlott Enberg describe the key components in a comprehensive tank management system to meet the safety requirements for the application. Lydia and AnnCharlott…

  • Remote Proof Testing Safety Level Switches

    Jim Cahill
    One of the necessities in managing safety instrumented systems throughout the IEC 61511 safety lifecycle is to perform periodic proof tests on the components in a safety instrumented function to verify proper function. A short 2:44 YouTube video, How to Remotely Proof-Test the Rosemount 2140:SIS shows how this proof testing can be performed remotely for safety level switches to save time & costs and reduce risk. …

  • Integrated versus Separate Control and Safety

    Jim Cahill
    Panelists at a session at the 2019 ARC Industry Forum , Safety Systems: Integrated versus Not? Does It Really Matter?, set out to discuss the pros and cons of the approaches and how they accommodate different risk factors. ARC Advisory Group’s Mark Sen Gupta moderated this panel which included executives from Air Products & Chemicals, Dow Chemical, Chevron Energy Technology, and exida. Mark covers the process safety…

  • Integrated versus Separate Control and Safety

    Jim Cahill
    Panelists at a session at the 2019 ARC Industry Forum , Safety Systems: Integrated versus Not? Does It Really Matter?, set out to discuss the pros and cons of the approaches and how they accommodate different risk factors. ARC Advisory Group’s Mark Sen Gupta moderated this panel which included executives from Air Products & Chemicals, Dow Chemical, Chevron Energy Technology, and exida. Mark covers the process safety…

  • Simplifying Safety Instrumented System Modernization Projects

    Jim Cahill
    One of my first assignments as a newly minted Electrical Engineer was to tend to a triple modular redundant (TMR) safety instrumented system (SIS) on an offshore Gulf of Mexico oil & gas gathering facility. This was back in the 1980s when these systems were introduced. Many manufacturers and producers have these older safety systems that have been in operation for decades. I mention this since I received a note from…

  • Simplifying Safety Instrumented System Modernization Projects

    Jim Cahill
    One of my first assignments as a newly minted Electrical Engineer was to tend to a triple modular redundant (TMR) safety instrumented system (SIS) on an offshore Gulf of Mexico oil & gas gathering facility. This was back in the 1980s when these systems were introduced. Many manufacturers and producers have these older safety systems that have been in operation for decades. I mention this since I received a note from…

  • Simplifying Safety Valve Proof Testing

    Jim Cahill
    A safety instrumented function (SIF) within a safety instrumented system (SIS) consists of a sensor, logic solver, and final element. As part of the IEC 61511 global safety standard, these elements within the SIF must be tested during the operational phase of the safety lifecycle. Of the 3 elements, the final control element, typically a safety valve, has mechanical movement which must be tested. In a Processing magazine…

  • Simplifying Safety Valve Proof Testing

    Jim Cahill
    A safety instrumented function (SIF) within a safety instrumented system (SIS) consists of a sensor, logic solver, and final element. As part of the IEC 61511 global safety standard, these elements within the SIF must be tested during the operational phase of the safety lifecycle. Of the 3 elements, the final control element, typically a safety valve, has mechanical movement which must be tested. In a Processing magazine…

  • Partial Stroke Test for Final Elements—Diagnostic Coverage Factors

    Jim Cahill
    Author: Riyaz Ali Partial stroke test is one of the viable means to check mechanical integrity of Final Element of Safety Instrumented Function (SIF) loop. Generally, end users struggle on question of credit of PST for improvement in SIL (Safety Integrity Level). IEC 61508 and IEC 61511 define diagnostic coverage factors (DCF), but do not provide a prescriptive way to estimate the number applied in real process…

  • Partial Stroke Test for Final Elements—Diagnostic Coverage Factors

    Jim Cahill
    Author: Riyaz Ali Partial stroke test is one of the viable means to check mechanical integrity of Final Element of Safety Instrumented Function (SIF) loop. Generally, end users struggle on question of credit of PST for improvement in SIL (Safety Integrity Level). IEC 61508 and IEC 61511 define diagnostic coverage factors (DCF), but do not provide a prescriptive way to estimate the number applied in real process…

  • Simplifying Burner Management System Architecture

    Jim Cahill
    Emerson’s Zach Brooks and Steven Kormann described how compliance with National Fire Protection Association (NFPA) with modern burner management and combustion control hardware systems has been simplified. They explored how recently released (and upcoming) standard changes have forced the evolution of best practices based on modern hardware solutions. The acceptance of SIL-capable instrumentation has become more commonplace…

  • Simplifying Burner Management System Architecture

    Jim Cahill
    Emerson’s Zach Brooks and Steven Kormann described how compliance with National Fire Protection Association (NFPA) with modern burner management and combustion control hardware systems has been simplified. They explored how recently released (and upcoming) standard changes have forced the evolution of best practices based on modern hardware solutions. The acceptance of SIL-capable instrumentation has become more commonplace…

  • Optimizing Pressure Relief Valve Lifecycle Management

    Jim Cahill
    Kevin Simmons Marcelo Dultra Pressure relief valves (PRVs) are critical safety and equipment protection devices to prevent overpressure conditions. They need ongoing maintenance to assure that they operate as designed for their intended applications. In a Valve magazine article, Lifecycle Management of Pressure Relief Valves , Emerson’s Kevin Simmons and Marcelo Dultra describe considerations for effective and efficient…

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