Engineering Safe Systems in Hazardous Environments

Posted by Steve Beyer on Dec 20, 2016 3:04:39 PM


Many companies employ systems of interconnected piping, pumps, accumulators, filters, heat exchangers, etc. and associated control systems to produce a specific set of conditions or products in a manufacturing or production process. Optimation specializes in this space, delivering such systems on skids or in pods for food, chemical, industrial coatings, or other products. Often these systems are designed and engineered to yield an environment for controlling processes using gases such as nitrogen or argon, etc. This requires use of specific technologies and materials, combined in such a way that they not only deliver the right pressures and volumes, but also employ the proper materials, fittings, piping, and valves. We also must consider the safety features that accompany such conditions in the presence of electricity which introduces a whole other set of risks.

Electrical equipment installation in atmospheres with flammable gases or vapors, flammable liquids, combustible dusts, ignitable fibers or filings represent a risk for fire and explosion. Areas with possible fire or explosion risks due to explosive atmospheres and/or mixtures - are called hazardous (or classified) locations or areas. These areas in North America (United States and Canada) are historically classified with the Class/Division system. In Europe and the rest of the world - but also more and more in North America - the “Zone” system is used. The hazardous area classification system determines required protection techniques and methods for electrical and other spark creating installations in the location.  

The Class/Division/Group system is based on the National Electrical Code (NEC) where:

  • Classes - defines the general nature of the hazardous material in the surrounding atmosphere;
  • Divisions - defines the probability of hazardous material being present the surrounding atmosphere;
  • Groups - defines the type of the hazardous material in the surrounding atmosphere;

We quite often see applications where a prospective user calls for conditions that fit into a Class I environment and sometimes unknowingly find themselves also specifying a Division I (“Class I/Div. I”) scenario where the configuration is particularly hazardous because flammable gases or vapors are present (or may be present) in quantities sufficient to produce explosive or ignitable mixtures. Extra care and specific cautions have to be utilized to protect the process and primarily the people around the equipment; risk of serious danger can be high. We get concerned and consider the case to be Div. I when the substance referred to by class has a high probability of producing an explosive or ignitable mixture due to it being present continuously, intermittently, or periodically or from the equipment itself under normal operating conditions.

Choices for safeguards and personal protective equipment (PPE) are very critical at this point, and exacting materials specifications and controls play a big part in planning for and mitigating the safety protocols used in design and operation. It requires specialized knowledge and expertise to engineer and build a compliant and inherently safe system. Matching the specific conditions of one’s process and equipment design to the optimal set of safety options is a function of experience and knowledge, using good resources and best practices. Some widely-used protection schemes and techniques for protecting workers and equipment include:

  • Dust Ignition-proof
  • Explosion-proof
  • Intrinsically Safe
  • Non-“incendive"

One of the most-widely accepted and expected means to properly control and accommodate these risks is through the use of “intrinsically safe” components and in the design and configuration of a system where such risks are expected to be present. An intrinsically safe component is incapable of releasing sufficient electrical or thermal energy to cause ignition of a specific hazardous substance under normal or abnormal (fault) operating conditions; this means that intrinsically safe equipment and wiring will limit electrical and thermal energy to a level below that required to cause or start an explosion. Knowing what components to specify, and how to properly use them in a design is where experts such as Optimation’s process engineers, programmers, designers, and fabricators contribute so much to successful systems.

Before taking off on an important and potentially risky system project where such gases, electrical conditions, and other constraints are present, contact us to consult on how to maximize your project success and deliver the safest environment in which to operate it. 

Topics: Manufacturing, Safety, Skid Systems, Controls, Test Systems

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