Explosion-proof protection type Ex e is defined in the international standard IEC EN -7. Below, we explain the principle behind it, show example applications, and provide some useful tips for users and purchasers of Ex equipment.
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Ex e protection refers to enhanced safety, or reinforced construction. It is one of the most popular protections used in devices designed to operate in gas hazardous areas. You can find it, for example, in devices such as:
Ex e protection is intended for use in hazardous areas zones 1 and 2, i.e., atmospheres generated by the presence of flammable gases and vapors. It is not used in gas zone 0 or in dust zones 20, 21, and 22.
This protection concept allows for the possibility of an explosive atmosphere appearing inside the enclosure, which distinguishes it from, among others, Ex m (protection by encapsulation) or Ex p (protection by pressurized enclosure). At the same time, unlike Ex d protection, reinforced construction Ex e devices are not resistant to the pressure of an explosion inside them.
What is Ex e protection all about?
The Ex e protection concept involves reducing the likelihood of ignition sources (e.g., temperature, sparks, electric arcs) occurring on both the device’s enclosure surface and inside it. This task is primarily accomplished by:
The same type of explosion-proof protection can provide different levels of safety, which are defined in the PN EN -14 standard. Below you will find a table with these levels and their reference to the equipment category and the hazardous area in which the equipment can be used.
G – gases. D – dusts.
It is worth noting that Ex e devices are only available in Gb and Gc versions, meaning they are intended for use in hazardous areas zones 1 and 2 (gases and vapors).
What about other hazardous areas?
Zone 0: If we look at the list of devices for which Ex e protection is used, we quickly conclude that they are almost never used in Zone 0, i.e., in a tank where a gaseous explosive atmosphere is constantly present. How often in such conditions do we need to use a control panel or motor?
Dust zones 20, 21, 22: However, to use a device in dust hazardous areas (20, 21, 22), another type of protection, such as Ex t, can be used, which is a kind of equivalent to Ex e protection in gas zones. What the designation of a device with both types of protection looks like is shown below on the example of an explosion-proof lighting fixture.
Historically, Ex e devices often compete with Ex d devices. Each of these solutions has its advantages, with reinforced construction devices being the more versatile solution. Let’s compare both types of protection:
The data in the table above is an average, so before purchasing, you should conduct an independent analysis of the pros and cons.
Below are some examples with explanations. Here we will focus only on aspects related to the explosion-proof protections used in the device.
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If you also want to learn how to understand the remaining components of the feature, check out the article: Ex Markings: How to Correctly Select Equipment for Hazardous Areas [Guide + Tasks]
As a client, you should require the manufacturer to properly execute Ex devices. However, it is your responsibility to provide the complete set of the following information:
The phrase of essential security is usually used to describe products used in dangerous (explosive) areas. Essential safety and explosion-proof are to prevent the product from failing and prevent the failure of electrical processing equipment that cause explosion or fire.
As companies want to minimize the risk of explosion in dangerous areas, explosion -proof shells and essential safety shells become more and more important. It is common to have flames or vapor in many industrial, chemical and petroleum production environments. As a result, these dangerous areas have always been risked by destruction and loss of life.
However, it is difficult to distinguish the explosion -proof shell and the essential safety shell. Therefore, this article will help you better understand the two terms of "explosion -proof shell" and "essential safety shell" and their main differences.
Explosion-proof shell
Explosion -proof shell refers to the designed shell for any explosion in the specified area. The excess energy generated by the explosion is then dissipated through the flange and thread of the shell. Explosion -proof shells are usually designed with extended thread flanges to form a long flame path to cool and control the explosion in the shell. Therefore, any potential ignition will not be exposed to an external explosive environment. This method is called curb because it aims to curb the explosion.
Advantages and disadvantages
Therefore, the materials used to build a shell must be heavy and strong to bear and curb the explosion. This means that the cost of explosion -proof shells is higher, because materials for making shells (such as cast aluminum and steel) are usually more expensive. This is why explosion -proof shells are heavier and bulky than essential safety shells, which may cause installation and regular maintenance to be a difficult process. In addition, the power must be turned off during the maintenance of the explosion -proof shell, because any failure or spark in the circuit may cause explosion. Therefore, it is not allowed to open any explosion -proof shell for maintenance when the dangerous area is powered. at last, However, explosion -proof shells can inhibit the explosion of device running at high power, which cannot be achieved by the essential safety shell.
Essential safety shell
The essential safety shell is designed to limit the current, voltage, power and temperature of the circuit. Therefore, insufficient power in the essential safety shell may cause sparks or ignition in an explosive environment. This is also called prevention, because it does not allow any explosion first.
Advantages and disadvantages
The essential safety shell is usually cheaper than explosion -proof shells, because materials used to design the essential safety wiring are often cheaper. Unlike the circuit in the explosion -proof shell, the circuit in the essential safety shell does not need to be wrapped with heavy materials. Therefore, compared with explosion -proof shells, the installation and maintenance of the essential safe shell is much simpler. One of the most prominent benefits brought by the essential safety shell is that the power supply does not need to be turned off during maintenance. Due to the limited power involved, on -site maintenance is allowed.
However, because the essential security shell is running at a limited power, they cannot be used for equipment or equipment that requires higher power. Therefore, only explosion -proof shells can be used for higher power equipment.
MAM explosion -proof wiring box
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