Safety and risk reduction are both high priorities for operators in the process industry. Not only is it critical to maintain the health and safety of personnel, but past industrial incidents have caused extensive damage to nearby areas, causing harm to residents and the environment. Fortunately, there are avenues available to further the goal of maintaining plant safety and reducing risk.
One layer of risk prevention lies in the Safety Instrumented Systems (SIS) used in critical processes. It is crucial that sensors and measurement equipment deployed in these systems meet rigorous quality and reliability standards. Vortex technology provides a perfect balance between meeting these requirements and reducing the need for unexpected and costly maintenance shutdowns. Emerson’s certified safety integrity level (SIL) capable Rosemount™ 8800 Quad Vortex Flow Meter is the ideal solution for maximizing process efficiency and mitigating risk in critical applications.
The IEC 61508 Standard for Safety Instrumented Systems (SIS)
The role of SIS equipment is to interrupt a process’s control system in the event where an emergency shutdown is needed. For example, if a reaction taking place in a vessel were to get out of control, the tank could explode causing significant damage. Several layers of prevention and mitigation surround processes like these to keep accidents to a minimum. The control system normally keeps everything running as intended. Should an issue arise, the first layer of prevention is operator intervention. If this doesn’t work, the independent SIS is in place to safely shut down the system before the emergency escalates.
The IEC 61508 standard is used by manufacturers of SIS equipment to maintain quality of design and the integrity of safety lifecycle management of safety-related systems. Targeted SILs are chosen based on needed levels of risk reduction assigned to a given safety function. According to the IEC 61508 certification standards, SILs range from one to four, with one providing the least risk reduction and four the highest. A SIL capable instrument is one that can be used up to and including the SIL level noted on the certificate. To become certified, a device or system must meet IEC requirements for both hardware safety integrity and systematic safety integrity. All functional groups are examined including design, development, manufacturing, and procurement.
The Advantages of Vortex Flow Meters
The reliability and versatility of vortex technology makes it especially fit for use in Safety Instrumented Systems. Vortex flow meters can accommodate liquid, gas, and steam, as well as corrosive applications. They can withstand high process pressures and temperatures, are easily installed, and have no moving parts to maintain or repair. Emerson’s gasket-free, non-clogging meter design eliminates potential leak points and, in the rare case of sensor failure, features isolated sensors which can be replaced without breaking the process seal. They require low power consumption, which is especially useful in remote areas.
Certified SIL Capable Quad Vortex Flow Meters work well in SIS loops due to their dependability and ability to provide redundant flow measurements. They meet the requirements defined by IEC 61511, the process industry’s standard for SIS design, implementation, and operation, and also minimize unnecessary maintenance and unscheduled shutdowns.
How the Rosemount Quad Vortex Flow Meter Helps Achieve Your SIL
In designing a SIS loop, the main goal is to reach your targeted SIL. Each component in the loop is assigned a Probability of Failure on Demand (PFD), the chance the component will be in dangerous failure mode when it is needed to bring the process to a safe state. The cumulative PFD of all the SIS loop components is used to determine the SIL. Your Hazard and Operability Analysis (HAZOP) lets you know what SIL to target.
The Rosemount 8800 Quad Vortex Flow Meter is capable of up to SIL 3 certification. Dual independent shedder bars, quadruple sensors and sensing elements, and a quadruple transmitter configuration deliver the ultimate solution for process and safety measurements. With the Certified SIL Capable Quad Vortex Flow Meter, users can run three out of four transmitters to provide 2oo3 (two out of three) voting, while utilizing the fourth transmitter for the basic process control system. So, if one sensor fails, you can continue to operate while diagnosing the failed device. Not only does this ensure your SIL, but it also prevents process shutdowns from failed sensors when the process is under control.
Emerson’s Certified SIL Capable line is the most comprehensive Vortex offering for SIS applications. The quad is currently available in line sizes from 2-12 inches. Learn more at www.Emerson.com/RosemountQuadVortex
