Safe HMI operation

Our Editors Browse the Web Searching for the Latest Information on HMIs. See What They Found

This free white paper discusses a new generation in emergency stop switches for HMIs. For operators facing an emergency situation, using e-stop switches is the last possible measure to avoid an accident. Thus, e-stop switches must send a stop command to machines and systems without failure. Many international standards have been written to ensure e-stop switches meet functional and structural requirements. However, the structure of conventional e-stop switches can't shut down system operations when improperly installed or operated with excessive force. This paper explains the design of the next-generation e-stop switches, which achieve a safer HMI environment and change the concept of emergency stop switches. A direct link is at

Designing systems for installation in hazardous areas requires an understanding of division and zone classifications, and whether off-the-shelf components are appropriate. Control Design's senior technical editor, Dan Hebert, walks readers through the complexities of division and zone classifications, and delivers some guidance for getting the right components for your hazardous-duty application. The direct link is at
Control Design

This technical paper explores the basics of fire and explosion safety issues, legislation, regulations and standards around the world, and compares the Class/Division Hazardous Location versus Zone Hazardous Area Classifications and Protections primarily for oil and gas refineries, chemical processing and transport operations. Many charts and diagrams explain the differences between global standards, and show which standards apply in which countries. The paper also defines such basic terms as “intrinsic safety,” “explosion-proof,” “non-incendive” and more, as well as the responsibilities and obligations of HMI and panel builders under the standards. The link is at

The presentation, “HMI Design—The Good, the Bad and the Ugly—and What Makes Them That Way,” by Paul Gruhn, PE, gives a quick, basic introduction to proper HMI design best practices and shows why bad design makes for unsafe conditions, regardless of the environment. The link is at

For most process plants, it's not possible for all automation system components to be installed in non-hazardous areas. As a result, some form of protection is required to prevent fires and explosions that could occur when a hazardous gas and energy source combine. There are standards and associated products that, if properly designed, installed and maintained, virtually eliminate the risk of an accidental explosion in hazardous areas. This paper will compare, contrast and explain the IEC and NEMA standards and then explain how to protect automation system components—including HMIs—using either standard via one of the three main methods of protection: energy limiting, containment and segregation. The link to examine this free PDF is at