Technical readss from Comtest
Curb explosive potential with intrinsically safe tools
For those who work in industries where flammable materials are present—such as petrochemical and pharmaceutical plants, oil platforms, refineries, pipelines, and mining—the potential for an explosion is a daily reality
All it takes is a flammable material coming into contact with air and an ignition source.
As a practical matter, avoiding the ignition source—anything from a spark or electrical arc, to static electricity or a hot surface—is probably your best bet for preventing an explosion. That is why industries with potentially highly explosive environments are required to abide by a set of intrinsic safety standards that apply to all equipment used in those environments.
Devices that are certified as "intrinsically safe" (IS) are designed so that they are unable to release enough energy to ignite flammable material. Workers are not allowed to carry non-IS-rated tools through an IS classified area even if they aren't powered up, because the tool could accidentally be activated—creating a safety risk.
ATEX sets the global standard
The European Union (EU) 94/9/EC Directive, commonly referred to as ATEX (Atmospheres Explosible), is the primary IS standard for electrical and electronic equipment that is to be used in potentially explosive environments in EU countries. Adopted in 2003, ATEX establishes mandatory safety requirements for equipment sold for use in those environments and serves as a model for similar directives adopted around the world. In the United States, the NEC 500 and 505 codes define the requirements. NEC 505 is similar to ATEX in classification and related product markings of products used in hazardous areas.
Third-party accreditation bodies such as Factory Mutual Research or the Canadian Standards Association (CSA) certify that products meet ATEX regulations. To make sure you have the proper level of intrinsically safe tool for your environment, you should be aware of the various aspects of certification.
Equipment is categorized for use in classified areas based on its degree of protection:
- Category I = A very high level of protection
- Category II = A high level of protection
- Category III = A normal level of protection
Intrinsically safe equipment is rated by zone, which indicates the probability and frequency of flammable gases or vapours being present under normal operating conditions:
- Zone 0 = An area where gases are known to be present 1,000 or more hours a year. Only Category I equipment can be used in this zone.
- Zone 1 = Explosive gases are likely to be present between 10 and 100 hours a year. Only Category I and II equipment can be used in this zone.
- Zone 2 = Explosive gases are not likely to occur in normal operation but may be present for more than 1 hour and less than 10 hours a year. All three categories of equipment can be used in this zone.