scholarly journals Influence of the Pyrotechnic Igniter Composition Aging on Explosion Parameters of Dispersed Dusts

2021 ◽  
Vol 11 (22) ◽  
pp. 10728
Author(s):  
Zuzana Szabová ◽  
Richard Kuracina ◽  
Martin Sahul ◽  
Miroslav Mynarz ◽  
Petr Lepík ◽  
...  
Keyword(s):  
Benzoic Acid ◽  
Measurement Accuracy ◽  
Standard Sample ◽  
Barium Nitrate ◽  
Explosion Chamber ◽  
Explosion Pressure ◽  
Lycopodium Clavatum ◽  
Barium Peroxide ◽  
Pyrotechnic Composition

A commercially available pyrotechnic igniter was used according to the EN 14034 and ASTM E1226a Standards to study the explosiveness of dispersed dusts. Its pyrotechnic composition consists of 1.2 g of zirconium (40% wt.), barium peroxide (30% wt.) and barium nitrate (30% wt.). The energy released during the combustion of that amount of composition is 5 kJ. The article investigates the influence of aging of the pyrotechnic composition in the igniter on its initiation parameters. In the study, igniters of different years from date of manufacture were used: Igniter 1, manufactured in 2021 (less than 1 year from date of manufacture), and Igniter 2 (more than 2 years from date of manufacture). The study was performed in the KV 150M2 explosion chamber with a volume of 365 L and the 20 L sphere chamber with a volume of 20 L. A standard sample of Lycopodium clavatum was used in the KV 150M2 explosion chamber. Magnesium and benzoic acid were used as the samples in the 20 L sphere explosion chamber. The experiment showed that the explosion pressure Pmax of the igniter with more than 2 years from date of manufacture decreased by up to 10%, while the value of the explosion constant Kst decreased by up to 40%. The attained results proved that aging of igniters affects their explosion parameters and measurement accuracy.

scholarly journals Measurement and Calculation of Explosion Pressure for Hydroxyl Substituted Hydrocarbons Mixture

2018 ◽  
Vol 168 ◽  
pp. 06006
Author(s):  
Jan Skřínský
Keyword(s):  
Systematic Investigation ◽  
Explosion Chamber ◽  
Explosion Pressure ◽  
Temperature Range ◽  
Work Supports

Methanol as a biofuel requires information about the explosion parameters measured in air under various conditions in different volumes. Forty explosion pressures owing to the methanol-air mixture have been measured in the temperature range 298 – 423 K between Φ = 0.65 – 2.65 in 1 m3 explosion chamber. This work supports the systematic investigation owing to 0.005 m3 and 0.020 m3 volumes.

The Application of Aqueous Span 80 Composite Material in Methane Absorption and Explosion Suppression

2009 ◽  
Vol 610-613 ◽  
pp. 125-129 ◽  
Author(s):  
Zeng Zhi Zhang ◽  
Na Gu ◽  
Ji Fei Zhang
Keyword(s):  
Inorganic Salt ◽  
Explosion Hazard ◽  
Explosion Chamber ◽  
Explosion Pressure ◽  
Methane Absorption ◽  
Explosion Suppression ◽  
Absorbing Material ◽  
Span 80 ◽  
Mine Gas ◽  
Main Component

This paper aims to design a sort of aqueous atomization absorbing material which can absorb mine gas under coal mine to decrease the methane concentration and reduce the explosion hazard. The material was composed of water as matrix, Span 80 as methane absorbent, and inorganic salt as additive. Methane the main component of mine gas was used as model of mine gas. The influence of concentration of inorganic salt on absorption and the effect of different compound materials made of Span 80 and inorganic salt on absorption were studied using Head Space Gas Chromatography to determine the content of methane absorbed. Explosion chamber was used as experiment system to simulate mine gas explosion. The explosion suppression effects of absorbing materials were studied preliminarily in explosion chamber using the maximum explosion pressure and residual methane content after explosion as parameters. The results indicate that the absorbing material can absorb more methane than water and can partly inhibit the explosion of the mixture of methane and air.

Preparation of cross-sectional samples for near-surface TEM studies

1987 ◽  
Vol 45 ◽  
pp. 380-381
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless
Keyword(s):  
Standard Sample ◽  
Surface Region ◽  
Specimen Preparation ◽  
Thick Sheet ◽  
Drill Bit ◽  
Sample Holder ◽  
Metal Interface ◽  
Cross Sectional ◽  
Near Surface ◽  
Cold Worked

In thermal oxidation studies, the structure of the oxide-metal interface and the near-surface region is of great importance. A technique has been developed for constructing cross-sectional samples of oxidized aluminum alloys, which reveal these regions. The specimen preparation procedure is as follows: An ultra-sonic drill is used to cut a 3mm diameter disc from a 1.0mm thick sheet of the material. The disc is mounted on a brass block with low-melting wax, and a 1.0mm hole is drilled in the disc using a #60 drill bit. The drill is positioned so that the edge of the hole is tangent to the center of the disc (Fig. 1) . The disc is removed from the mount and cleaned with acetone to remove any traces of wax. To remove the cold-worked layer from the surface of the hole, the disc is placed in a standard sample holder for a Tenupol electropolisher so that the hole is in the center of the area to be polished.

TEM characterization of proton-exchanged LiNbO3 optical waveguides

1986 ◽  
Vol 44 ◽  
pp. 480-481
Author(s):  
W. E. Lee
Keyword(s):  
Refractive Index ◽  
Benzoic Acid ◽  
Optical Waveguides ◽  
Total Internal Reflection ◽  
Index Of Refraction ◽  
Optical Measurements ◽  
Lithium Ions ◽  
Wide Channel ◽  
Tem Characterization

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.

Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing

Methodology ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Juan Ramon Barrada ◽  
Julio Olea ◽  
Vicente Ponsoda
Keyword(s):  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Computation Time ◽  
Adaptive Testing ◽  
Exposure Rate ◽  
Control Parameters ◽  
The Impact ◽  
Two Alternatives ◽  
Selection Of ◽  
Maximum Exposure

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

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