In the constantly evolving world of technology, safety remains a top concern among engineers during development. Whether it’s a sensor in your car, your son’s handheld video game, or a surgically implanted medical device in your elderly neighbor, we need assurance that our products are intrinsically safe (IS) during use.
This is especially true when it comes to electronics used in already dangerous conditions. Atmospheres in mines, chemical plants, processing mills, tankers, and oil refineries can contain extremely hazardous areas that rely on intrinsically safe equipment to keep workers from harm’s way.
So, What Does 'Intrinsically Safe Equipment' Mean?
Basically, intrinsically safe electronics allow for safe operation in hazardous areas by limiting the electrical or thermal energy available for ignition. Common industrial equipment like motor brushes and switches are at risk of:
- Internal sparks
By simplifying the circuitry, controlling internal temperatures, and adjusting components to reduce dust-caused shorts, this equipment protects workers from a variety of threats.
How Does It Work?
Fundamentally, intrinsic safety is a low-energy technique where the current, voltage, and power is reduced to a level too low to cause ignition. Generally, the maximum level of power available is less than 1.3W.
Additionally, maximum temperature must be controlled, and among the six classes used to define temperature levels, electronics meeting the T4 designation are considered IS. This is because at this level, temperatures won’t exceed 135 degrees C (275 degrees F).
Which Electronics Apply?
Many electronics can be found in intrinsically safe forms. These include:
- Mobile phones
- Gas detectors
- Even flashlights!
Why is intrinsically safe equipment important in these products? Simply put, lives depend on it.
Communications inside a mine are integral to the safety of the workers, and failure of those lines could result in an accident. Electronics used in environments producing flammable gases like hydrogen and propane cannot have a risk of sparking or overheating, or an explosion is imminent.
Intrinsically Safe Vs. Explosion-Proof
Explosion-proof products are capable of containing an explosion inside an enclosure. It will keep flames or hot gases from escaping the housing. The term "explosion-proof" does not indicate the product is capable of withstanding a strong external force.
Intrinsically safe electronics receive their classification because they are low-power enough that they won't cause an explosion in the first place.
What Are the Benefits?
Besides the inherent safety benefits of meeting intrinsically safe requirements for electronics, there are other upsides to consider when deciding what you need out of your product:
- Avoiding the cost, bulk, and tedious installation of explosion-proof enclosures.
- Maintenance and diagnostic work can be performed without shutting down production and ventilating the area.
- Potentially lower insurance premiums due to reduced risk.
Things to Note
While individual parts can be IS-certified, the entire system must be designed to be intrinsically safe. It requires full documentation of all components and wiring used in the system.
Immediately following installation, an inspection will take place, followed by periodic inspections throughout the life of the equipment. This is to identify any damage, deterioration or unapproved replacement of IS components.
While IS equipment can in some cases serve as a replacement for explosion-proof equipment, that is not always the case. This is due to the reliance on low power and temperatures.
For more on keeping electronics running properly and safely, check out the Ultimate Guide to PCB Testing, Prototyping, & Inspection below:
(Editor's Note: This article was originally published in March 2018 and was recently updated.)