www.eaton.com/gb/en-gb/markets/machine-building/service-and-support-machine-building-moem-service-eaton/blogs/difference-between-sil-and-pl.html#:~:text=SIL%20is%20particularly%20well%2Dsuited,more%20suitable%20for%20individual%20machines.
Safety Integrity Level (SIL) and Performance Level (PL) are both measures used in the field of functional safety to assess and quantify the reliability and performance of safety-related systems. However, they are associated with different international standards and are applied in different contexts.
1. **Safety Integrity Level (SIL):**
- **Definition:** SIL is a measure of the reliability of a safety instrumented system (SIS) in achieving its safety function. It is defined in the IEC 61508 and IEC 61511 standards.
- **Application:** SIL is commonly used in process industries, such as chemical, petrochemical, and oil and gas, where the need for safety systems is critical to prevent accidents and protect personnel, the environment, and assets.
- **Assessment:** SIL is determined through a risk assessment that considers the severity of potential consequences, the likelihood of hazardous events, and the ability of the safety system to mitigate the risks.
2. **Performance Level (PL):**
- **Definition:** PL is a measure of the performance of a safety-related control system as defined in the ISO 13849 standard. It is primarily used in the context of machinery safety.
- **Application:** PL is applied in manufacturing and industrial settings where machinery and equipment are involved. It is relevant to safety functions that use programmable electronic systems or other types of control systems.
- **Assessment:** PL is determined based on factors such as the architecture of the safety-related control system, its components, and the reliability of the safety functions it performs.
In summary, while SIL and PL both deal with the safety and reliability of systems, SIL is primarily associated with safety instrumented systems in process industries, while PL is associated with safety-related control systems in machinery and industrial applications. The choice between SIL and PL depends on the specific industry and the type of system or equipment being evaluated. It's important for engineers and professionals in these fields to be familiar with the relevant standards and guidelines to ensure compliance and enhance safety.