This article was originally published on March 21, 2022, and updated on July 9, 2025.
As manufacturing and industrial operations have become increasingly automated and reliant on electronic systems for safety, the importance of standardized functional safety measures has grown. Protecting system operators and maintaining safe, reliable processes are now top priorities across all industries.
Whether you’re protecting workers from injury, preventing environmental spills or avoiding costly equipment damage, ensuring your pressure instruments are Safety Integrity Level (SIL) certified will play a key role in minimizing risk in your critical process applications. For example, when using pressure switches in your application, you will want to consider the SIL rating of your system or device.
As a global expert in pressure and temperature instrumentation, we are often asked to explain the benefits of SIL certification. Read this article to learn more about this safety standard, the organization that created it, where SIL-certified instruments are used and the pressure switches we offer that can help prevent worker injury or damage to your equipment.
What is Safety Integrity Level (SIL) Certification?
SIL certification was established by the International Electrotechnical Commission (IEC), a global standards organization that prepares and publishes standards for all electrical, electronic and related technologies used in industries across the globe.
The IEC introduced Safety Integrity Levels (SIL) to classify a system's reliability in performing its safety function. The four SIL (Safety Integrity Level) numerical ratings, as defined by the IEC 61508 standard, indicate the required reliability of a safety function:
- SIL 1: Low risk, basic safety requirements.
- SIL 2: Moderate risk. This level may require redundancy in alarming and testing to ensure safety.
- SIL 3: High risk. Failure could lead to injury or equipment damage. SIL 3 systems often require redundant safety design and fault annunciation.
- SIL 4: Extremely high risk that requires additional safety considerations to reduce the risk. SIL 4 designs are intended to prevent catastrophic failures.
How SIL Certification Applies to Pressure Switches
SIL certification also applies to individual field devices, such as pressure switch sensors, which often serve as critical safety shutdown mechanisms. In industrial settings, approximately 50% of switch applications require some type of safety shutdown (high- or low-pressure limit controls).
When a dangerous condition is detected, the switch sends a signal to the Safety Instrumented System (SIS), which initiates an automatic shutdown or intervention. The SIL rating of a switch reflects its reliability in performing this critical safety function during both normal operation and abnormal conditions.
Why Would You Need SIL Certification?
A safety system is considered functionally safe when it continues to work properly, or shuts down safely, despite unexpected failures. These systems are designed to protect people, equipment and the environment under all conditions, including during faults. SIL-certified instruments are required in systems where a single failure could cause serious consequences.
Figure 1: Pressure Switch Applications That Require SIL Certification
These environments demand instruments that are designed to withstand harsh conditions, are reliable and able to meet performance standards under fault conditions.
Ashcroft's SIL 3 capable switches, including the Ashcroft® A-Series Pressure Switch and Ashcroft® B-Series Pressure Switch, are built with specific construction criteria to meet these requirements, giving engineers and operators confidence that these instruments:
- Function reliably in safety-critical applications such as fire and gas systems, turbine control, gas burner management and more.
- Help protect their people, the environment and their equipment
- Support regulatory compliance and safety audits
SIL-certified switches have become effective solutions for companies looking to reduce risk and enhance safety in their operation.
Ready to learn more?
Now that you’ve learned about SIL certification, you can help ensure the safety of your operators and equipment. And with the right pressure switch, you will be able to ensure that your pressure instrumentation is reliable and efficient, and your application is accurate.
For your reference, we've included a few more relevant articles that may interest you:
- What is a Pressure Switch?
- Using Pressure Switches to Trigger Alarms or Process Shutdown
- Choosing a Pressure Switch: 9 Factors to Consider
- Class and Division Codes on Explosion-Proof Pressure Switches
- When Should You Use an Electronic Pressure Switch?
Feel free to contact us anytime to speak with an industry expert and get all your questions answered.
