One of the most common questions we receive from our customers is, “Which protection method is suitable for our business?”. And that is a valid question. After all, your explosion-proof enclosure must be compatible with the environment in which it is being installed to ensure your workers’ safety.
However, with various protection methods for selection – each tailored to different hazardous environments – how do you select the enclosure that is ideal for your business? In this article, we will look at two common protection methods (Ex d and Ex e) to help you better understand which enclosure is more suitable for your business.
What are Ex d and Ex e enclosures?
Firstly, let us clarify what explosion-proof enclosures entail. Based on the naming convention, it is easy to assume that this protective equipment is immune to external explosions. However, this is not true. The term “explosion-proof” refers to the equipment’s ability to contain any internal explosion or spark that happens within the enclosure.
Explosion-proof enclosures are designed to protect the surrounding environment by containing any explosion or spark that forms within the enclosure. Therefore, the equipment must resist extreme heat to ensure the fire does not escape the enclosure. Hence, these enclosures serve as a safety measure, preventing any spark generated from malfunctioning equipment from escaping and igniting any external flammable substances in the hazardous environment.
Now that we have established what an explosion-proof enclosure is, let us look at the two most common types, as per the IEC (International Electrotechnical Commission) standard – Ex d and Ex e enclosures.
Ex d standard (IEC60079-1)
Ex d enclosures are designed to contain an explosion, and the accompanying pressure that is generated, safely. They prevent fire or sparks from escaping the enclosure and into the explosive environment. The focus is on containment rather than prevention.
Ex e standard (IEC60079-7)
Ex e enclosures are developed with increased safety in mind. As such, these enclosures must be able to withstand extreme temperatures and sparks internally and externally. They are also designed to be cool running, thus preventing arcs, sparks, and hotspots from occurring. Unlike Ex d enclosures, Ex e enclosures focus on prevention rather than containment.
Learn More: Ex e VS Ex d Enclosures – What’s The Difference?
Installation and maintenance of Ex d and Ex e enclosures
An explosion-proof enclosure must be suitably thicker to contain an explosion and the pressure that comes with it. As a result, Ex d enclosures are usually bigger, bulkier, and heavier than their Ex e counterparts. Due to their lighter weight and more compact design, Ex e enclosures are easier to install and maintain.
Another feature that makes Ex e enclosures much easier to maintain is the lack of flame paths. Because Ex d enclosures are designed to contain an explosion, they must incorporate flame paths in their designs. These flame paths are crucial in extinguishing flames before they can escape into the external environment.
The challenge in maintaining an Ex d enclosure lies in the number of bolts (tightened to a specific torque) used to maintain a suitable flame gap. A technician must remove these bolts sequentially to access the internal components for maintenance procedures. As a result, the process is more complicated and time-consuming. After the maintenance is complete, the technician has to ensure the correct flame gap is retained when putting the housing back together. Failure to do so will invalidate the Ex certification.
Adding further to this, you might find it tough to find suitable Ex d enclosures that are certified for IIC gas groups. As the gases that fall under the IIC gas group are classified as a significant risk, Ex d enclosures designed for such environments must have tighter flame gaps. So they are more complex to manufacture. As a result, there are fewer Ex d enclosures for IIC applications, and those available are usually more expensive and challenging to maintain. Since Ex e enclosures do not utilise flame paths, they do not face this issue.
One last thing to note is that most Ex d enclosures are unsuitable for installation in environments below -20° C. This is because of changes in the property of a gas or vapour at low temperatures. Conversely, because Ex e enclosures are designed to prevent an ignition source from occurring, they are likely to have a much broader temperature rating. Therefore, they are more suited to cold environments.
We hope what we have shared has allowed you to have a better understanding of which explosion-proof enclosure is more suitable for your business. Regardless of your decision, you should note the maximum voltage of the explosion-proof enclosure when installing it.
For example, at Supermec, our Ex d and Ex e junction boxes have a maximum voltage of 1000V. As such, they are not suitable for any transformer with a voltage rating above 1000V. Failing to comply with the safety standards could jeopardise your business operations and the safety of your workers. Therefore, it is essential to always pay attention to the product specifications of your explosion-proof equipment.
If you require assistance in choosing the most suitable explosion-proof electrical equipment for your business, do not hesitate to contact our friendly sales team at email@example.com or drop us a call at +65 68619522 to find out more about our explosion-proof solutions.