Yokogawa to Release ProSafe-RS Lite, an SIL2 Version of the ProSafe Safety Instrumented System

Tokyo, Japan - October 14, 2020

Yokogawa Electric Corporation (TOKYO: 6841) announces the development and the late January 2021 release of ProSafe-RS Lite, a safety integrity level 2 (SIL2*1) version of the ProSafe™ series safety instrumented system. ProSafe is a core product of the OpreX™ Control and Safety System family.

With the addition of ProSafe-RS Lite, Yokogawa's portfolio of safety instrumented systems will cover all risk reduction levels from SIL2 to SIL4, allowing customers a greater range of choices in their selection of a safety instrumented system that meets installation cost and site SIL requirements. Yokogawa will continue working to make plants safer with ongoing enhancements to ProSafe series functionality.

ProSafe-RS Lite
ProSafe-RS Lite

Development Background

When an abnormal condition is detected in a plant operation, a safety instrumented system can automatically put a process into a predetermined safe state by initiating a control action such as an emergency shutdown. Safety instrumented systems are considered to be the last line of defense in protecting the safety of plant operators, plant facilities, and the environment.

Yokogawa's ProSafe series of safety instrumented systems consists of two types: The solid-state ProSafe-SLS, which has a magnetic core and meets requirements up to SIL4, and the programmable ProSafe-RS, which meets requirements up to SIL3 (the highest level possible with this type). ProSafe series systems are typically deployed as emergency shutdown systems for major plant facilities. However, safety instrumented systems are also needed for utilities such as fire prevention and extinguishing systems, and boilers that do not require the highest safety integrity levels (SIL 3 and 4). To meet the need for SIL2-capable safety instrumented systems, Yokogawa has developed ProSafe-RS Lite. By expanding its safety instrumented system portfolio, Yokogawa gives its customers a wider range of choices in selecting the system that best meets their installation cost and site SIL requirements.


A ProSafe-RS Lite system can be configured from controllers, an extensive variety of I/O modules, communication modules, and peripheral devices.

  1. SIL2 with a single module configuration
    Unlike the many safety instrumented systems on the market that meet the SIL2 requirement by multiplexing modules, ProSafe-RS Lite accomplishes this with a single module configuration. In addition to reducing engineering and other installation costs, this holds down the cost of operating and maintaining the system.

    Furthermore, the use of a dual-redundant module configuration ensures that the system can maintain SIL2 level performance and remain operational even if a module fails.
  2. Integration with control systems
    ProSafe-RS Lite can be integrated with the CENTUM VP integrated production control system and the ProSafe-RS system, allowing operators at CENTUM VP human machine interface (HMI) stations to monitor in a unified manner the safety instrumented systems that control emergency shutdowns systems, fire prevention and extinguishing systems, boilers, and other facilities. One benefit of this is that operators have immediate access to all the alarms generated by safety instrumented systems, ensuring a prompt response in the event of an emergency.
  3. Ease of adding an SIL2 system to existing systems
    ProSafe-RS Lite supports the same control bus (Vnet/IP*2) as CENTUM VP and ProSafe-RS. It is therefore easy to add ProSafe-RS Lite to systems that have been built using Vnet/IP. Furthermore, the ProSafe-RS safety engineering tool can be used with ProSafe-RS Lite, which eliminates the need to install and learn new tools.

Major Target Markets

Oil and gas, petrochemicals, chemicals, electric power, pulp and paper, pharmaceuticals, food, iron and steel, water supply and wastewater treatment, non-ferrous metals, metal, cement, etc.


For use in fire and gas systems, emergency shutdown systems, and burner management systems

*1 Established by the International Electrotechnical Commission (IEC), a safety integrity level (SIL) indicates the relative level of risk provided by a safety function. SILs 1 through 4 are defined by IEC 61508. Compared to a plant where safety measures are not in place, at SIL2 the risk factor is reduced to between 1/100 and 1/1,000. At SIL3, the risk factor is in a range between 1/1,000 and 1/10,000. At SIL4, the risk factor is in a range between 1/10,000 and 1/100,000.

*2 A control network developed by Yokogawa that features high reliability and quick response. Vnet/IP complies with the IEC61784-2 international standard.

About the ProSafe series


Released in February 2005, the ProSafe-RS safety instrumented system helps to prevent accidents by detecting abnormal conditions in plant operations and initiating emergency actions such as a plant shutdown. TÜV Rheinland, an independent certification body, has certified that ProSafe-RS can be used in SIL3 applications. Unlike conventional safety instrumented systems and distributed control systems, which are regarded as having different roles and functions and operate separately, the operation of ProSafe-RS and the CENTUM integrated control system can be fully integrated. ProSafe-RS is highly regarded by users and has been installed in more than 2,800 projects worldwide (as of September 2020).

Since 2017, Yokogawa has provided a comprehensive set of services, systems, and software packages under the Sustainable Safety Instrumented System Solution concept that helps to ensure continued safety in plant operations.


ProSafe-SLS is a solid-state safety instrumentation system that was released in 1997. Equipped with a magnetic core, ProSafe-SLS can be used in SIL4 applications. This system is in use at approximately 800 locations around the world, primarily in high-integrity pressure protection system (HIPPS) applications.

About OpreX

OpreX is the comprehensive brand for Yokogawa's industrial automation (IA) and control business. The OpreX name stands for excellence in the technologies and solutions that Yokogawa cultivates through the co-creation of value with its customers, and encompasses the entire range of Yokogawa's IA products, services, and solutions. This brand comprises the following five categories: OpreX Transformation, OpreX Control, OpreX Measurement, OpreX Execution, and OpreX Lifecycle. One of the product groups that make up the OpreX Control category is the OpreX Control and Safety System family, which includes the ProSafe-RS Lite. With its various OpreX Control solutions, Yokogawa is able to quickly effect changes for its customers that lead to a transformation in such areas as management and operations, and provides highly reliable control technology that ensures high efficiency, high quality, and safe and stable plant operations.

With the OpreX brand, Yokogawa will deliver integrated solutions that address specific needs and support its customers in their efforts to transform and grow their businesses.


About Yokogawa

Founded in 1915, Yokogawa engages in broad-ranging activities in the areas of measurement, control, and information. The industrial automation business provides vital products, services, and solutions to a diverse range of process industries including oil, chemicals, natural gas, power, iron and steel, and pulp and paper. With the life innovation business, the company aims to radically improve productivity across the pharmaceutical and food industry value chains. The test & measurement, aviation, and other businesses continue to provide essential instruments and equipment with industry-leading precision and reliability. Yokogawa co-innovates with its customers through a global network of 114 companies spanning 62 countries, generating US$3.7 billion in sales in FY2019. For more information, please visit www.yokogawa.com.

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