Explosion prevention and mitigation in plants which process, generate and store combustible dusts

Combustible dusts which are present in workplaces are a significant hazard which cannot be ignored by the plant owners, managers and workers. Combustible dust deflagrations and explosions have caused large numbers of deaths and catastrophic property damages in various industries, ranging from pharmaceutical plants to sugar factories. One may say that dust explosions in process industries always start inside process equipment such as mills, dryers, filters. Such events may occur in any process in which a combustible dust is handled, produced or stored, and can be triggered by any energy source, including static electricity, friction and hot surfaces. For any combustible dust type, several important parameters have to be taken into account when designing and using protective systems: i.e. the ease with which dust clouds ignite and their burning rates, maximum explosion pressure, maximum rate of explosion pressure rise. These parameters vary considerably depending on the dust type, their knowledge being a first step for carrying out a proper explosion risk assessment in installations which circulate combustible dusts. The paper presents the main aspects concerning explosion protection which have to be taken into account when designing protective systems intended to be used in explosive atmospheres generated by combustible dusts and the importance of selecting the proper explosion protection technique.

Considerations regarding the choice of cable glands for electrical equipment used in potentially explosive atmospheres

The evaluation of explosion-proof electrical equipment for certification is particularly important given the risk of explosion and must be minimized. This in order to ensure the safety of life, health of workers, to prevent damage to goods and the environment when they meet the essential security requirements at European level. Directive 2014/34 / EU states that equipment used in explosive atmospheres must be designed to operate without endangering the environment for which it is intended. This paper presents a comparison between the different types of cable glands for electrical apparatus by comparing some common characteristics that are important for maintaining the integrity of explosion protection. Consequently, this paper intends to be the precursor of a practical guide for the selection and implementation of different types of protection on the apparatus intended for use in areas with hazard of explosive atmospheres, both for designers and manufactures. This state of fact is negatively more emphatic because, lately, the groups of standards from this field in the world, Europe and Romania have a peculiar dynamic caused especially by the homogenisation and generalisation process opened and maintained by IEC.

Considerations regarding test methods against dust and water ingress protection for Ex equipment

The explosion danger in all industries where explosive atmospheres generated by the mixture of combustible dusts or flammable gases with air may form, must be treated as a major hazard, as the explosions that may occur can seriously affect both health and safety people, as well as the environment. It is therefore necessary to assess the explosion risk and to establish appropriate measures to reduce it to acceptable levels in accordance with the requirements of the European Directives. An essential element in the assessment of the explosion risk for electrical and non-electrical equipment intended for use in potentially explosive atmospheres is the way in which an appropriate normal degree of protection is provided through the equipment housing (protection against touching of dangerous parts inside the equipment housing and protection against the ingress of dust and water inside it). The aim of the paper is to highlight compliance with the requirements of the ATEX Directive, given that this protection is a basic requirement for explosion protection and to present the important elements to be considered for the assessment of the normal degree of protection and the development of harmonized test methods with the requirements of European standards.

Evaluation of equipment used in Ex atmospheres - interdisciplinary field

The risk of explosion becomes significant when, in the industrial field, flammable substances such as gases, vapours, mists, dusts, lint and fibres may be present. If they are present in sufficient quantity, the risk of explosion is imminent. On the other hand, the measure of shutting down the technical equipment, in the context of the presence of explosive atmospheres, is not an acceptable measure in all situations. As examples are the parts of installations that have safety functions: ventilation installations, installations for monitoring the concentration of flammable substances and other safety parameters. Explosion protection of technical equipment shall be evaluated and tested in order to validate it. The testing process of the technical equipment for the purpose of explosion protection certification is situated at the confluence of several engineering fields: mechanical, electrical, chemical, etc. The first part of the paper deals with the risk of explosion and presents the explosion protection of the technical equipment. The systematized presentation of the technical equipment tests is performed in the second part of the paper. Among the conclusions it is mentioned that although the field of tests in explosion atmospheres is an interdisciplinary one, its coherence is ensured by the specific standards.

A Functional Safety Assessment Methodology for Explosion Protection with Application to a Variable Frequency Drive System

Modern explosion protection equipment, protected by traditional explosion protection technology (as defined by the international electrotechnical commission (IEC) publication IEC60079-ff series standards) and electrical/electronic/programmable electronic (E/E/PE) safety-related systems, is becoming ever more complex in coal mine development and petrochemical industry; thus, the possibility of failures in their operation is also growing. It is well-known that E/E/PE safety-related systems can be used to actively control dangerous sources, with real and expected levels of reliability, if they have been qualified according to the IEC61508-ff series standards. To uniformly evaluate the safety integrity level (SIL) of the explosion protection function of traditional explosion protection technology and E/E/PE safety-related system technology, this study analyzed the ability of these types of protection to remove the ignition risk residual, evaluating the failure rates of safety devices. The key objective of this paper is the presentation of a new equipment protection level (EPL) assessment method for explosion protection equipment based on a functional safety assessment. The method is applied to a variable frequency drive (VFD) system, and the results show that the EPL of the explosion protection equipment evaluated by this method is consistent with the EPL corresponding to the traditional explosion protection type of the IEC60079-ff series standard. Meanwhile, the flexible configuration of explosion protection safety devices and E/E/PE safety-related systems enables explosion protection equipment of different EPL levels to be designed.

Storage of white sugar in large-capacity silos

In all sugar factories there is a need to store the white sugar produced for a longer or shorter period of time. With today‘s standard factory sizes, storage capacities of more than 100,000 t per factory are necessary. Large-capacity silos such as those built in various designs in the sugar factories are used for this purpose. In addition to an overview of the various silo designs, information on the conditioning and heating of the silos and the requirements for explosion protection are compiled.

Substantiation of Application of the Strategic Planning Methods in Order to Improve Efficiency of the Automated Systems of Fire and Explosion Protection at the Fuel and Energy Complex Facilities in the Special Conditions

This paper presents substantiation of the obligatory application of the strategic planning methods in order to improve efficiency of the automated systems of fire and explosion protection (ASFEP) at the facilities of the fuel and energy complex (FEC) in the special conditions. To this end, the technological production process of the FEC facilities is divided into destructive and creative subprocesses. It is assumed that the events that cause the potentially dangerous situations, which are connected with fires and explosions, form the destructive subprocess. The activities, which are carried out within the framework of fire safety plans at the FEC facilities and which are controlled by the shift on duty, form the creative subprocess. Events of the first subprocess reduce efficiency of the ASFEP, while events of the second subprocess increase efficiency of this system. Authors of the article propose the continuous curve of recovery of the ASFEP efficiency in order to ensure modelling the type of influence of various rehabilitation measures. Two kinds of the exponential functions enveloping the moments of fire and rehabilitation are analysed for these subprocesses. The article describes the graph of actual rehabilitation of the ASFEP efficiency taking into account assumptions concerning nature of these functions. The total efficiency of the rehabilitation measures within the creative subprocess consists of the partial efficiencies of the measures, which are included to individual plans of various subsystems of the ASFEP (subsystems of the first and second levels). These partial shares of efficiency have been analysed from the point of view of their dependency on the period of performance of these measures, on their funding and management. It was established that management of the relevant measures, which is determined with the help of the strategic planning methods, is the most significant parameter in this model.

Summary of requirements for the use of cells and batteries in potentially explosive atmospheres

The use of wireless equipment in the industrial field is a modern trend both in terms of communication equipment, monitoring of gas concentration, environment or installations but also for remote controls and power backup. The energy source for such equipment are cells and batteries. The first part of the article addresses the risk of explosion and the peculiarities of flammable atmospheres. The second part was dedicated to the presentation of the types of cells suitable for use in explosive atmospheres. The last part presents a summary of the specific requirements of cells and batteries regarding the explosion protection.