SIS在现场仪器中

最近的一项研究表明，有44％的事故是由于仪器规格不佳，其中6％的事故是由安装和调试期间错误引起的，而由于设计和实施错误而发生了15％。这意味着在运营开始之前，有65％的工业事故已准备就绪。

“我们经常宁愿认为事故是操作员错误的原因，但现实是它们通常是仪器问题的结果，”在安全期间，电气和控制系统工程的技术总监Mark Murphy说。Emerson Process Management的年度用户小组会议上的仪器系统（SIS）会议。

根据墨菲的说法，仪器安全有三个关键：
• Know that SIF (Safety Instrumented Functions) is important for every component in your system, so give equal amounts of attention to each device.
• Understand SIL (Safety Integrity Level) ratings. Part of this understanding means knowing that using a SIL 2 transmitter with a SIL 2 PLC and a SIL 2 valve does not equal a SIL 2 SIF.
•专注于设备的生命周期，而不仅仅是其实现。

To help attendees better understand what differentiates SIF from SIS from SIL, Murphy said that SIF covers individual devices such as sensors, controllers, and final elements such as valves and actuators; SIS (Safety Instrumented Systems) is collection of SIFs; and SIL is a device’s specified integrity level related to SIF requirements.

Paying close attention to the safety aspects of instrumentation is critical because 92 percent of system failures can be traced to the final element (50 percent of failure causes) and sensors (42 percent of failure causes).

“Everyone wants to be involved in designing the logic solver component of a system, but this only accounts for 8 percent of failures,” Murphy added. “So [instrumentation] is where the efforts really need to be focused.”

Beyond sensors, field devices, and final element considerations, Murphy also pointed to two other system components that can have a direct impact on system operation and, therefore, system safety. These two components are solenoid valves and instrument air supplies.

Solenoid valves tend to be forgotten, but they are the cause of 50 percent of valve failures. Murphy cautions engineers and technicians to be aware of the build-up of particles in the solenoid valve. He adds that the air supply to the solenoid valves should be filtered, monitored, and protected from outside elements.

仪表空气供应是SIS的外部部分，因此在容量通常会增加时，它们在植物改造过程中往往会被忽略。结果，仪器空气供应通常不会随着工厂容量而增加，这可能导致压降。墨菲说：“作为安全准备的一部分，您需要考虑如果这种空气供应系统失败，将会发生什么。”