Fine Dust Creation during Hardwood Machine Sanding

Effect of Grit Size on Airborne Particle Concentration and Size Distribution during Oak Wood Sanding

Adverse health effects caused by exposure to airborne particles have been detected in recent years, however there is little knowledge about exposure to ultrafine particles with a diameter <100 nm. In this study, particle number concentration and size distribution in a range of particle diameters from 10 nm to 10 µm were determined during oak wood sanding. A hand-held orbit sander in combination with three types of grit size (P60, 120 and 240) of sandpaper were used. Measurements were obtained using a portable particle size distribution analyzer and an optical particle size spectrometer, carried out at 15-min intervals for each treatment by static sampling in the breathing zone. We also compared the optical particle size spectrometer to the aerosol monitor in order to evaluate the mass concentration of airborne particles in the range of 1 to 10 µm in diameter. Sanding paper with the finest grit, P240, showed a significantly higher number concentration of ultrafine particles, compared with P60 and P120 grits. The differences among particular grit size were statistically significant for microparticles. The size distribution of particles during sanding was not affected by grit size. For each grit size, apparent peak values of ultrafine and microparticle number concentrations were determined at approximately 15 nm, and 0.1 µm, respectively. Optical particle size spectrometer and aerosol monitor showed comparable results of mass concentration for the respirable fraction.

The Dust Separation Efficiency of Filter Bags Used in the Wood-Based Panels Furniture Factory

The relationship between the conditions of the use of filter bags made of non-woven fabric and the separation efficiency of wood dust generated in a furniture factory was experimentally determined in the conditions of pulse-jet filtration using a pilot-scale baghouse as waste during the processing of wood composites. The experiments were carried out, and we describe the results of the experiment as consisting in assembling one type of filter bag in two dust extraction installations operating under different operating conditions in the same furniture factory. The filter bags working in the assumed time intervals were then tested for their separation efficiency using a stand for testing filtration processes on a pilot scale. The test results are presented in the form of graphs and tables describing both the characteristics of the dust extraction installations and the filter fabric used, as well as the separation efficiency of bags used at different times in different industrial operating conditions for each of them. The conducted research allowed us to recognize the phenomenon of filtration in relation to a very important value, which is the separating efficiency of dust extraction in various operating conditions of dust extraction installations in a furniture factory during the long-term use of filter fabrics. The obtained results allowed us to determine the separation efficiency for the tested bags at a level of over 99.99% and to state that this separation efficiency increased with the working time of the bag. The structure of the outlet dust from filters in the wood composites processing factory constitutes an element of the working environment if the purified air is returned in a recirculation circuit to the interior of the working area. Thanks to this, it is possible to predict the separation efficiency in the long-term use of filter dust collectors for wood dust in furniture factories.

Fire Parameters of Spruce (Picea abies Karst. (L.)) Dust Layer from Different Wood Technologies Slovak Case Study

The issue of the formation of wood dust particles in the work environment is still an actual topic in terms of its impact on employee health and the risk of fire or explosion in a woodworking operation. This article deals with the characteristics of spruce dust (Picea abies Karst. (L.)), which was taken from several types of wood technology. Experimental samples of spruce dust were taken from four types of sawing technologies, including grinding, briquetting and from the suction device container. The physical parameters of the samples taken were monitored and the particle size analysis was determined. The granulometric composition of the samples is significantly different. The sample of spruce wood dust from sawing has the most numerous fraction (250 µm), while the sample from grinding has the most numerous fraction 63–250 µm (87%).The aim of the paper was to monitor the minimum ignition temperature of the settled spruce dust layer and to look for a significant dependence of the minimum ignition temperature and ignition time on the type of spruce dust sample. A significant dependence was not confirmed. Significant moisture dependence of the samples was confirmed; the highest humidity was observed in the container, the lowest in sawing.

The Dynamics of Mycobiota Development in Various Types of Wood Dust Depending on the Dust Storage Conditions

Solid or processed wood, and wood waste in particular (dust, shavings, etc.) are the source of a number of health hazards for workers in the wood industry. One of the many negative health effects of exposure to fungi is allergic diseases caused by hypersensitivity reactions. The aim of this study was to investigate the effect of wood species and the degree of dust fragmentation, resulting from processing conditions and storage conditions on the level of wood dust contamination with microscopic fungi during 1 year of storage. An additional aspect of the research was the assessment of the influence of the antioxidant wood bioactive compounds on the development of A. alternata microscopic fungi. It was found that the conditions in which wood dust is stored significantly affect the development of microscopic fungi, especially fungi of the genus Alternaria. The results indicate that temperature is the determining factor, not the relative humidity of the air. The degree of dust fragmentation resulting from the sanding paper grit also has a significant impact on the development of microscopic fungi. Finer dust is more susceptible to the development of microscopic fungi. The antioxidant activity of the wood from which the dust was formed was found to have a significant impact on the development of microscopic fungi. An inverse relationship was observed, indicating the strong activity of antimicrobial substances. Gaining comprehensive knowledge of how all factors affect each other is a key step in understanding the risk and implementing measures to prevent and protect the work environment.

Performance of Filter Bags Used in Industrial Pulse-Jet Baghouses in Wood-Based Panels Furniture Factory

The study specifies the value of the dust resistance coefficient in the process of wood dust filtration in a pilot-scale test stand. The experiments were carried out for one type of filter material—polyester with a PP film previously used in different production lines. Filter bags from the filtering installation of the processing line for narrow surfaces of furniture panels of the honeycomb structure with a chipboard frame, HDF, natural veneer cladding, and a line of CNC drilling machines, were taken into account. Before the pilot-scale tests, the bags had been in use in industrial installations from zero to nine months. All tests were performed under identical filtration conditions. The values of the dust resistance coefficient depend on the operating time and the conditions in which filtration is carried out in an industrial plant, and increased from 6507 s−1 to 10,208 s−1 for the bags from the filter of the narrow surfaces processing line and to 29,729 s−1 for the bags from the filter of the drilling line. The most important factor influencing the properties of the filter bag in the process of wood dust filtration in an industrial filter is the cleaning pulses frequency.

Evaluation of Marblewood Dust’s (Marmaroxylon racemosum) Effect on Ignition Risk

The paper deals with the selected characteristics, such as moisture, average bulk density, and fraction size, of tropical marblewood dust (Marmaroxylon racemosum) that influence its ignition risk. Research was focused on sieve analysis, granulometric analysis, measurement of moisture level in the dust, and determination of the minimum ignition temperatures of airborne tropical dust and dust layers. Samples were prepared using a Makita 9556CR 1400W grinder and K36 sandpaper for the purpose of selecting the percentages of the various fractions (<63, 63, 71, 100, 200, 315, 500 μm). The samples were sized on an automatic vibratory sieve machine Retsch AS 200. More than 65% of the particles were determined to be under 100 μm. The focus was on microfractions of tropical wood dust (particles with a diameter of ≤100 µm) and on the impact assessment of particle size (particle size < 100 µm) on the minimum ignition temperatures of airborne tropical dust and dust layers. The minimum ignition temperature of airborne marblewood dust decreased with the particle size to the level of 400 °C (particle size 63 μm).