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Significance of the chemical ignitors´ explosion pressure on Pm and Pressure Ratio in the 20 L chamber

Autoři: Janovský Břetislav | Karl Jan | Janovský Prokop

Rok: 2024

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

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Jazyk	Název	Abstrakt	Klíčová slova
eng	Significance of the chemical ignitors´ explosion pressure on Pm and Pressure Ratio in the 20 L chamber	Ignition behaviour of chemical ignitors became more and more discussed in conjunction with their influence on dust and hybrid mixture explosion parameters in 20 L chamber. Specifically, a turbulence generated by ignitors´ action and/or preconditioning of the system by a large and hot fireball. The explosion pressure generated by chemical ignitors is included in the Standards by mean of so-called Pressure Ratio (PR) (ASTM E1226 - 19) and corrected explosion pressure Pm (ASTM E1226 – 19, EN 14034:2011). Igniters explosion pressure should also be considered when ignition of the dust is evaluated in e.g. Go/No-Go tests. The aim of presented work is influence of measured explosion pressures generated by igniters on calculations of PR and Pm compared with igniters explosion pressures calculated according to equations given by the Standards. Influence of the dust concentration (mass of the dust inside the chamber) on igniters explosion pressures was also tested. Two 5 kJ Sobbe ignitors generated explosion pressures of about 0,73 barg in tests without dust in contrast with 1,6 barg of explosion pressure calculated according to EN 14034:2011 equation. Then four concentrations (125, 250, 500 and 750 g/m3) of Talc were dispersed in the tests with two 5 kJ ignitors. The same tests were done with the mixture of Talc (80 % by weight) and Lycopodium Clavatum (20 % by weight). The dust served as a heat sink and the maximum explosion pressures decreased to about 0,52 barg for both dusts tested and the highest dust concentrations. If the PR is calculated using 1,6 barg as calculated ignitors´ overpressure, then the values of PR are lower by almost 1 bar compared to PR values using measured value of igniters in only air. If the values of ignitors´ explosion pressure in given dust concentration are included, then PR increases with increasing dust concentration to another 0,2 barg at 750 g/m3. Pm values are also significantly influenced by used igniters explosion pressure. Pm value fo	dust explosion, pyrotechnic ignitor, explosion pressure, pressure ratio

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