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Improvement of explosive mixtures flammability parameters conversion method in intrinsically safe electrical circuits

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Last Updated on Thursday, 16 May 2013 10:22

Published on Thursday, 15 November 2012 14:21

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Authors:

I.А. Bershadskiy, Cand. Sci. (Tech.), Associate Professor, State Higher Educational Institution “Donetsk National Technical University”, Senior Lecturer of the Department of Power Supply of the Industrial Enterprises and Cities, Donetsk, Ukraine

Ye.А. Тukmacheva, Private Joint Stock Company “TETZ-Invest”, Technician-Constructor, Torez, Ukraine

Abstract:

Purpose. To develop a procedure allowing clarification of the dependence between the parameters of flammable explosive gas mixture of group II and the same parameters of explosive gas mixture of group I. Also for the case when the explosive mixture for which no tests were carried out in the explosion chamber and for which only the minimum inflame energy is known should be considered, the task of converting hazardous parameters of the known energy efficiency in the discharge was set.

Methodology. The existing method of conversion of parameters of control flammable gas mixtures has several disadvantages, which lead to significant errors in calculating of probable values. A new dependence for conversion of the parameters for the other mixture has been designed and the comparative evaluation of the experimental energies of ignition has been carried out. To increase the accuracy of the calculation the influence of the multiplicity of reduction of the minimum ignition energy value of a gas mixture on energy release into a discharge taking into account different electrode spark mechanisms and discharge duration has been figured out.

Findings. Results of calculation of flammable energy have been compared with experimental data listed in normative document GOST R51330.10-99 and those received by V.P. Didenko methodology. It has been found out that the presented method reduces the error by 22% for IIA group mixtures of and by 35% for IIB group mixtures.

Originality. The analytical method of converting values of the energy and the duration of the discharge determining risk of sparking in explosive environments of subgroups IIA, IIB, IIC at various switching speeds of sparking mechanism has been further developed. In comparison with already known methods it shows more accurate probable data. For the first time the possibility of converting the parameters of flammable explosive mixtures in condition of luck of input information has been proved.

Practical value. Potentialities of the method of assessment of low-voltage electrical chains use in explosion-proof equipment have been broadened and examples of its application for obtaining of flammable options more aggressive than 8.3% methane-air mixture are shown.

References:

1. ГОСТ Р51330.10-99 Электрооборудование взрывозащищенное. Часть 11. Искробезопасная электрическая цепь „i“. – [Введ. с 01.01.2001]. – М.: Госстандарт России, 2000. – 118 с.

GOST R 51330.10-99 Electrooborudovanie vzryvozashcheshchennoye. Chast 11. Iskrobezopasnaya elektricheskaya tsep „i“. [Valid since January 1, 2001], (2000), Gosstandart Rossii, Moscow, Russia.

2. Ковалев А.П. Моделирование параметров разряда и расчетная оценка искробезопасности при размыкании электрической цепи / А.П. Ковалев, И.А. Бершадский, З.М. Иохельсон // – М.: Электричество. – 2009. – №11. – С. 62–69.

Kovalev, A.P., Bershadskiy, I.A. and Iokhelson, Z.M. (2009), “Modelling of parameters of discharge and evaluation of spark at breaking danger”, Elektrichestvo, no.11, pp. 62–69.

3. ГОСТ Р52350.11 Электрообрудование для взрывоопасных газовых сред. Часть 11. Искробезопасная электрическая цепь „i“. – [Введ. с 28.12.2005]. – М.: Стандартинформ, 2007. – 95 с.

GOST R52350.11 Elektrooborudovanie dlia vzryvoopasnykh gazovykh sred. Chast 11. Iskrobezopasnaya elektricheskaya tsep „i“, (2007), [Valid since December 28, 2005], Standartinform, Moscow, Russia.

4. Некоторые особенности взрывчатых газообразных смесей и паров жидких горючих [Электрон. ресурс] – 2007 – Режим доступа: http: // piroman.org/articles/ 30.html, свободный. – Загл. с экрана. – Яз. рус.

“Some features of explosive gaseous mixtures and vapors of combustible fluids” (2007), available at: http: // piroman.org/articles/ 30.html.

5. Диденко В.П. Зависимости минимальной воспламеняющей энергии от длительности разряда и скорости коммутации / Диденко В.П. // Проблеми експлуатації обладнання шахтних стаціонарних установок / Зб. наук. Праць. – Вип. 102–103. – Донецьк: ВАТ „НДІГМ ім М.М. Федорова“, 2008–2009. – С. 395–404.

Didenko, V.P. (2008–2009), “Dependence of minimal ignite energy on duration of discharge and switching speed” Problemy ekspluatatsiyi obladnannia shakhtnykh statsionarnykh ustanovok, Issue 102–103, Published by VAT „NDІGМ im. M.М. Fеdоrоvа“, Donetsk, pp. 395–404.

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