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Ex p way of protection

Tuesday, 1 February 2011 PDF icon Ex p way of protection
As consequence of last month's newsletter, we received some requests regarding the Ex p type of protection and we are happy to satisfy our readers expectations. The internal overpressure protection mode is based on the concept of segregation. Basically, it prevents the penetration of the explosive atmosphere in enclosures containing sparkling equipment through the injection of clean air, which creates an excess an overpressure, preventing gas from coming into contact with the trigger factor.

Main protection methods

Saturday, 1 January 2011 PDF icon Main protection methods
We begin this new year analyzing some of the main ways of protection used in systems installed in areas with potentially explosive atmosphere for the presence of gas. Relating with the three main protection techniques (containment, prevention and segregation), exist many others ways to apply the basic principle of the method. Each method is specific to certain applications and impossible to apply to others. Over the time, unspecific techniques have been attempts to adopt to certain applications, leading to disastrous consequences and, often, major damage. In recent years, standards have been heavily modified, and, even if existing, have been amended to be harmonized with international standards IECEx.

International Standard Ex n

Wednesday, 1 December 2010 PDF icon International Standard Ex n
In Zone 2 the probability of presence of explosive atmosphere is between 30″ and one hour during a year, and the risk level is very low. Between 70% and 80% of the hazardous areas inside a plant can be classified as Zone 2, and it is essential that the designer duly knows the protection type of the electrical equipment installable in such areas. The use of oversized equipment, in fact, could involve a huge waste of money and no advantages in terms of safety. This method of protection has been developed in the United Kingdom many years ago to be used in safety condition in Zone 2 reducing the costs of traditional equipment in Ex “d” or Ex “e” protection. Ex “n” protection method is applied to the equipment having the features described on the International standard IEC 60079-15:2010.

Installations in hazardous areas for the presence of combustible dust

Monday, 1 November 2010 PDF icon Installations in hazardous areas for the presence of combustible dust
In the last two newsletters, we analyzed the risks arising from the presence of combustible dust and, subsequently, we considered the method of classification of hazardous areas. In this newsletter, we will describe what types of protection can be used and how the installations are performed. In order to design an electrical system respecting the principles of safety against explosion in hazardous areas for the presence of combustible dust, the new EN 60079-14-2 standard is the reference. This standard is part of the whole new standard group resulting directly from IEC requirements which replaced the EN 50281 series standards.

Classification of areas with presence of dusts

Friday, 1 October 2010 PDF icon Classification of areas with presence of dusts
In the last newsletter, we have analyzed the danger of explosion due to the presence of combustible dust. In this newsletter, we will take a look to the classification of hazardous areas due to the presence of combustible dust, according to the provisions of the new rules which, as we shall see, come directly from the IEC international standards acquired by CENELEC and by the national regulation. The danger of explosion, as we saw in previous newsletters, can occur not only in places where gas, vapors or mists are present and where are normally used electrical installations that follow European regulations in force for over thirty years. It can occur also in plants where dust are machined during the normal operation and that might create a dangerous atmosphere, which could cause an explosion.

September, vintage time

Wednesday, 1 September 2010 PDF icon September, vintage time
September has come It's vintage time, the crops have been harvested in recent months and the barns and silos are now full of wheat and flour. Man has always lived with food powders, but only in the recent few years has understood what is the danger of an incorrect treatment in the handling and storage of these products. The devastating explosions, which periodically occur in rooms where large quantities of combustible dusts are stocked, have attracted attention and both the causes and the means to avoid them were subject of important studies. It’s not a modern phenomenon; in more than 200 years can be reported "explosions of dust”. The first recognized and recorded explosion of dust occurred in a flour warehouse in Turin in 1785. At that time, the windmills used since the mid-14th century for grinding cereals were gradually replaced by steam turbines, more efficient but also more dangerous. Another great explosion, occurred in Germany in 1887 in the New Mills of Weser Hameln, caused the death of thirty people and injured a large number.

August is the month of Maintenance

Thursday, 1 July 2010 PDF icon August is the month of Maintenance
August is usually the month of scheduled maintenance. During this month, the plants are shut down in order to proceed with the control of efficiency and safety of machinery and equipment. A regular maintenance is essential to maintain equipment, machineries and work environment safe and reliable. The lack of maintenance or improper maintenance operations can cause extremely dangerous situations, accidents and health problems. Maintenance itself, however, is a high-risk activity because some of the dangers arising from the nature of work. It runs in all sectors and in all workplaces. Consequently, maintenance workers may be exposed to various dangers more than other employees.

Lighting of places with risk of explosion

Tuesday, 1 June 2010 PDF icon Lighting of places with risk of explosion
The correct lighting of work places is a growing concern in order to guarantee the safety of people who works on plants. In particular, in electrical plants installed in hazardous area, lighting features are considered as a means to reduce risks of explosion. About 80% of our sensorial perception is visual and needs light as a vehicle of information, to interpret information from visible light reaching the eyes. A good illumination helps to see and recognize things, but also improves working performances and physical wellness, since it increases concentration and reduces tiredness. Equipment installed in classified zones, hence, have to guarantee the ex-proof protection and a good light stream in order to guarantee work operations in safety conditions.

Ex “d” protection mode

Monday, 1 March 2010 PDF icon Ex “d” protection mode
Without retracing the whole theory about how an explosion occurs, we just remind you that three factors are necessary: the combustible material, the combustion agent and the ignition energy. The combustible material and the combustion agent, called explosive mixture, must be present in percentage defined within two limits to be triggered by a spark or an electric arc. Beginning from this theory, all the different modes of protection have been studied. Over time, they led to the various standards on how to design and manufacture safe equipment which can be used in areas with potentially explosive atmospheres.

The new classification of hazardous areas

Monday, 1 February 2010 PDF icon The new classification of hazardous areas
In each area in which there is a process that causes a raising of temperature of flammable substances and their evaporation, such as hydrocarbons, can produce a leak of gas or of vapor which, in contact with flames or sparks caused by electrical processes, may explode. This event can happen both during normal operations and in case of breakdown or accident. Talking about these events, it is usually to cite a refinery as an example because it is, perhaps, the place where an explosion can easier happen. But the same conditions can occur in other chemical plants, or even in simple and seemingly innocuous places, such as, a painting room or a room where charge forklift batteries.