Pepperl+Fuchs Blog

Ex d and Ex e: 2 Explosion Protection Types Cleverly Combined

Posted by Thomas Kasten on Fri, Oct 16, 2015

Ed. Note: In this video Thomas Kasten, Product Marketing Manager for Systems+Solutions, explains the features of the explosion protection type flameproof Ex d. With Ex d, potential ignition sources are contained inside a sturdy enclosure, so the surrounding environment is never in danger. Just about anything can be installed in this type of enclosure. However, the cost of medium to large Ex d enclosures can be very expensive. The solution: a combination of an Ex de enclosure with an Ex e termination and control unit. This helps eliminate the need for a large Ex d enclosure, which drastically cuts down the cost of the solution. It also saves time and money during maintenance, installation, and any future modifications to system. The other benefits of these Ex de solutions are demonstrated in the video.

Explosion Protection Equipment




Hello, I am Thomas Kasten, Product Marketing Manager for Systems+Solutions with Pepperl+Fuchs. Today I would like to show you the features of the explosion protection type flameproof Ex d as well as the benefits of combining the Ex d and Ex e protection types.

You might know Pepperl+Fuchs is a specialist for explosion protection, especially with Ex i intrinsic safety. But, we do have several more types of protection in our portfolio.

Mostly, the field devices are specially designed to prevent explosions. Consequently, these devices have to be certified for use in hazardous areas.

But there are two types of explosion protection that allow the use of standard automation components in those dangerous areas. One of these is flameproof Ex d, which we will discuss today.

The basic idea of Ex d might sound strange, since an explosion is not prevented but only contained. Of course, the surrounding environment is never in danger.

Technically speaking, the potential ignition sources are installed inside an sturdy enclosure.

If an explosion does happen, it will remain confined inside the enclosure. The surrounding atmosphere is not ignited; humans and the production plant stay safe and sound.

The biggest advantage of Ex d protection is that you can install just about anything in that enclosure, from simple circuit breakers or transformers to complete plant control systems.

These standard industry components are produced in high volumes and thus are less costly than the certified components. Furthermore, devices that are not available in explosion-proof versions can be used in hazardous areas, thanks to Ex d. One very important point you need to remember: the power dissipation of the installed devices must not be too high.

The surface of the enclosure must not exceed the ignition temperature of the surrounding gas. So, the arrangement of the components inside the enclosure has to eliminate those "hot spots."

Enclosure cable entries and screw fastenings of the lid have to withstand the explosion pressure.

Furthermore, the flange needs to meet certain dimensions and tolerances in order to quench the flame before it reaches the outer edge.

As you see, each Ex d solution requires quite some planning, appropriate certification and, of course, documentation. For example, at Pepperl+Fuchs, all devices are controlled thoroughly from the first design through shipment. The final certification comes on top of that.

Opening an Ex d enclosure on site is very arduous since very strict safety regulations must be followed - an effort you surely want to avoid.

It gets much easier when the Ex d enclosure is combined with an Ex e termination and control unit. Maintenance is more flexible, the installation will be much faster, and modifications at a later stage are a lot easier.

The Ex e enclosure is connected via special line bushings with the enclosure above.

This stainless steel flange prevents dirt and moisture from entering the enclosure and facilitates cleaning of the surfaces.

To cover individual requirements, the enclosures are available in various sizes and for all gas groups up to IIC. You can choose aluminum or stainless steel enclosures. Viewing windows in the lid are available, too.

As you see, all operating elements are installed in the Ex e control station. This example shows an ammeter, a control switch and various push buttons and LED indicators.

A typical Ex de application example is the protection of an integrated control and safety system (ICSS) on board an offshore drilling rig. An appropriate stainless steel enclosure would protect against corrosive atmospheres and other environmental influences.

If you have requirements in your plant that cannot be met by Ex i - Ex e - or any other type of protection – then an Ex de combination could be the right solution.

It's even better if you have the right partner who covers everything from the first specification through procurement and installation of the components to final certification and FAT.

Our worldwide Solution Engineering Centers stand ready to support you wherever – whenever. Customized solutions for hazardous locations. Get the SEC Guidebook

Topics: Explosion Protection Equipment

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