Experimental study of minimum ignition temperature of spent coffee grounds

The aim of this scientifi c paper is an analysis of the minimum ignition temperature of dust layer and the minimum ignition temperatures of dust clouds. It could be used to identify the threats in industrial production and civil engineering, on which a layer of combustible dust could occure. Research was performed on spent coffee grounds. Tests were performed according to EN 50281-2-1:2002 Methods for determining the minimum ignition temperatures of dust (Method A). Objective of method A is to determine the minimum temperature at which ignition or decomposition of dust occurs during thermal straining on a hot plate at a constant temperature. The highest minimum smouldering and carbonating temperature of spent coffee grounds for 5 mm high layer was determined at the interval from 280 °C to 310 °C during 600 seconds. Method B is used to determine the minimum ignition temperature of a dust cloud. Minimum ignition temperature of studied dust was determined to 470 °C (air pressure - 50 kPa, sample weight 0.3 g)

Ignition activation energy of materials based on polyamide 6

This contribution is aimed to compare the values of the ignition activation energies of two types of polyamide – Slovamid 6 FRB and Slovamid GF 50 LTS. Samples were isothermally stressed at fi ve different temperatures between 500 °C a 550 °C, while the time to initiation of the fl ame combustion was monitored. Subsequently from the measured times were compiled Arrhenius plots under which activation energy of ignition of both polymers were calculated. The values of activation energies were 106 kJ.mol-1 and 158.0 kJ.mol-1 for Slovamid 6 FRB 4 and Slovamid 6 GF 50 LTS

Investigation of spontaneous combustion tendency of vegetable oils by the means of differential thermal analysis

The potential of vegetable oils to undergo violent thermal oxidation is long-known problem. The process of this oxidation is investigated by the means of differential thermal analysis. Polyurethane foam was saturated with Tung oil rich in unsaturated fatty acids at three different mass rations, and airfl ow at three different rates is introduces to the sample to ensure suffi cient volume of air for oxidation. The samples were thermally stressed both dynamically and isothermally. The results were compared to results of standard differential Mackey test

Software design to calculate of vibration for a more effective assessment of the safety of the working environment

A lot of software that is developed simultaneously with the development of new measuring devices are very difficult to control. The results obtained from the software for measuring the vibration must be adjusted for the respective weighting factors which is very complicated and time consuming. This paper deals with design of software to calculate human exposure to vibration in the working and living environment. Presented software developed at the Institute of Integrated Safety, which counts with all the weighting factors. It allows quick results without after treatment weighting factors. Presented software includes all known methods for calculating the vibration acceleration. It’s based on knowledge of the protection of man and his health against the negative effects of vibration. The measured data are evaluated according to the current legislation of the European Union. Simple layout software doesn’t have a good first impression, but it’s control is very swift and practical. Every reader needs to read about it below

Determination of fire and explosion characteristics of dust

The aim of this paper is to approximate danger of dust clouds normally occur by determining their explosion characteristics. Nowadays, dusty environment is phenomenon in the industry. In general, about 70% of dust produced is explosive. Dust reduction in companies is the main purpose of the national and European legislative. Early identification and characterization of dust in companies may reduce the risk of explosion. It could be used to identify hazards in industrial production where an explosive dust is produced. For this purpose several standards for identification and characterization of explosion characteristics of industrial dust are being used

Operation of the Suction System during the Production of a Mixture of Polypropylene and Polyethene Granulate from the Point of View of the Risk of Possible Fire and Explosion of Combustible Dust

This article deals with the operation of the suction system with the risk of fire and subsequent explosion of combustible dust during the operation of screw extruders and their equipment. Machines process a mixture of polyethylene and polypropylene to a granular form. It describes the suction device from the suction attachments to the separator at the selected workplace and points out specific technological problems of the device, together with measures for its solution

A new approach to the assessment of the reduction in visibility caused by fires of electrical cables

Electricity is the most important form of household energy and one of the most important forms of energy for industry and transport. Electrical distribution in construction and transport is almost exclusively implemented using electrical cables. One of the unresolved problems associated with electrical cables is the release of smoke and the resulting reduction of visibility in case of fire in the area. In this study, a new approach was developed to assess the reduction of visibility in an area affected by an electrical cable fire. This approach is based on the determination of the critical ratio of smoke volume (in the smoke layer and exhausted from the fire compartment) to the length of the burning cable, through which the visibility of reflective and illuminated signs was reduced to a lower limit value (a standard of 10 m). The input data for this approach was the extinction area of the smoke released from one meter of burning cable and the length of the cables in the area. This approach was used to test two power cables (CHKE-V J3x1.5 and CHKE-R J3x1.5) and one signal cable J-H(St)H 1 x 2 x 0.8 with the B2(ca), s1, d1, a1 fire reaction class. The smoke extinction area of the examined cables was determined using a cone calorimeter at a heat flux of 50 kW/m(2). The obtained data showed that in order to maintain a visibility of 10 m for reflective signs, the critical ratio of smoke volume to length of burning cable was 7.5 m(3)/m. For illuminated signs, the critical ratio was 2.8 m(3)/m. The relationship between burning length and visibility allows the calculation of visibility in the fire compartment affected by cable fire only from cables length.Web of Science53art. no. 4