There are two popular techniques used for explosion protection in hazardous areas. One is the Explosionproof technique and the other is Intrinsic Safety.Which is a better technique? Explosionproof or Intrinsic Safety?
We will see a brief comparison between the two techniques now, so that we can then conclude which is better.
The Explosionproof technique is very popular and it is older than Intrinsic safety. It is a brute force type of protection. In this technique, the parts of the electrical or electronic equipment is encased in a strong specially designed housing, such that even if an explosive gas mixture, or an explosive vapor mixture, or a combustible dust mixture enters it and causes an explosion, the housing can withstand it. Furthermore, the hot gases that could escape get cooled due to the peculiar design structure of the equipment.
Thus the explosionproof philosophy is based on the assumption that one cannot rule out minor explosions that may happen due to sparking in a hazardous area, therefore we accept it and design in such a way as it does not cause a larger explosion or fire in the hazardous area.
It can be used for any equipment including heavy duty equipment like electrical motors.
Intrinsic Safety philosophy
Intrinsic safety has a philosophy of prevention. Thus a spark is sought to be prevented from being generated in the hazardous area, by using various means. Hence even if explosive mixtures of gases, vapors or dusts are present, the equipment itself will not generate enough sparking energy to ignite it, either because it is itself incapable of generating enough energy to cause this, or due to the use of a Safety barrier, called an Intrinsic Safety Barrier. The barrier prevents high energy levels in the hazardous area. Thus explosions and fires are prevented.
The most common kind of barrier used is a Zener Barrier, followed by Galvanic Isolators.
However the downside of using this technique is that it can be used only for low energy equipment such as instrumentation transmitters, switches. LED lamps, etc. It cannot be used for heavy electrical equipment such as electrical motors.
Where can I learn more about this?
Both Explosionproof and Intrinsic Safety techniques have their advantages and disadvantages. The design engineer can select the technique based on the application. You can learn more about explosionproof protection technique in the Hazardous Area Instrumentation Course. You can learn more about Intrinsic safety protection technique in the Intrinsic Safety Course.
There is no single correct answer to the question, whether to use Explosionproof or Intrinsic safety. It depends on your requirements and the circumstances.