Intrinsic Safety vs. Other Environmental Protection
Intrinsic safety is a method used to prevent equipment from causing fires and explosions in areas with hazardous atmospheres such as explosive gas-air mixtures. Equipment and wiring is intrinsically safe if it is incapable of releasing sufficient electrical or thermal energy to cause ignition of a hazardous atmosphere in its most ignitable concentration.
"European and North American Markets for Intrinsically Safe Equipment," a report from Venture Development Corp., Natick, Mass., examines the use of intrinsically safe solutions vs. other methods of hazardous environment protection and the motivation for the adoption of intrinsic safety.
Equipment going into hazardous areas for intrinsically safe applications is classified as either simple or nonsimple devices. Simple devices such as switches, thermocouples, RTDs, noninductive potentiometers and resistors have limitations on voltages, currents and energy. Nonsimple devices such as field transmitters, solenoid valves and many other types of equipment can create and store energy levels high enough to create an explosion if they are not limited. For these applications, the devices have safety limits on the amount of inductance, capacitance and temperature operating levels. Field wiring to these devices is through intrinsic safety barriers that are located outside of the hazardous region. The barriers limit the voltage and current levels to the devices below those that could cause an explosion.
According to the report, most users are using multiple methods of hazardous environment protection, including explosion- and flame-proof devices, the pressurization/purging of units, encapsulation of equipment, non-incendive equipment, fiber optics in place of wire, and increased safety measures. One of these methods alone may not be sufficient or suitable for all situations and installations because of specifications and regulatory issues. However, most users prefer one method to the others. The report finds that for European operations, the greatest share of protection is via the use of intrinsic safety. In contrast for North American operations, much greater use is made of explosion-proof methods.
For the complete report and its findings, call (508) 653-9000 or visit www.vdc-corp.com.