Intrinsic safety is non-negotiable when it comes to hazardous locations.
The moment a certain area is classified as hazardous (with a potentially explosive atmosphere), you must take quite a few steps to eliminate potential ignition sources.
This endeavor starts by considering the fire triangle: oxygen, fuel and a source of ignition – these are the elements that contribute to causing an explosion. In most hazardous areas, at least two of them are present.
Intrinsic safety is complex and there are countless provisions that any company with hazardous areas must take. Let’s analyze the basics.
The Basic Requirements of Intrinsic Safety
The main responsibility of the design engineer is to eliminate all the ignition sources. This is done by limiting thermal and electrical energy to a level below the one that could ignite the hazards in a certain area.
According to the classification of the area, you might even need to use installation tools that cannot cause sparks. Such tools are typically made of aluminum or a similar material.
Every intrinsic safety device in any hazardous area must use intrinsic safety barriers. Intrinsic safety barriers are devices created to limit the voltage and current. These are the typical culprits that cause energy sparks in the signal and power conductors of a device.
There are three basic conditions that IS barriers must meet when used in hazardous locations:
- The device has to be certified
- The more dangerous the zone is, the safer the barrier must be
- The wiring and design methods have to be compliant with the current intrinsic safety regulations
Even a facility that may initially appear to be non-hazardous can hide several hazardous areas. It is important to note that even the smallest such area can cause a disaster. This is why the installation of a control system in a hazardous area is a process that needs to be conducted by multi-disciplinary teams.
The law requires that any facility manager properly classifies all areas that might have an explosive atmosphere. A single person is not enough to handle this classification properly. Typically, the control system designer works closely with other specialists (for instance, plant engineers, safety or operations staff) to accurately determine the classification of the area.
Another important collaboration is that between facility managers and vendors or manufacturers of IS barriers. For example, at GMI International we work closely with all our clients to help them determine the type of devices they need.
Our experts are happy to scrutinize all our clients’ intrinsic safety system design plans and even check all the components and make sure that they are right for the expected hazardous area. Even if some of our clients employ safety experts, it’s important to note that requirements and standards in this area change. A significant part of our business in ensuring that we know and respect all these standards. More importantly, we can make sure that your investment in intrinsic safety devices brings a long-term ROI by recommending those devices that will not become obsolete too soon.
By choosing the right IS barrier, you can limit the heat and sparks that can cause explosions in electrical devices under both normal and abnormal conditions. IS barriers are crucial in protecting low-power devices like solenoids, sensors, various instruments and LEDs.
Other types of protection include using equipment that is explosion-proof or enclosures, as well as pressurizing or purging the enclosure/device. Typically, these additional methods are used in combination with IS barriers, as the latter aren’t always suitable. For instance, when safe energy levels vary according to the classification of the area. IS barriers limit current and voltage, but it’s hard to pinpoint the right levels in a variable atmosphere.
Last but not least, the wiring and installation for IS barrier devices have to match the design drawings. You do not need to seal a standard industrial enclosure that is used with IS devices, like for other types of protection.
There are numerous other requirements for the application of IS barriers, aside from the basic ones here.