Dust Diameter Research Articles

Equivalent diameter of standard quartz dust used as a test aerosol for the dust respirator.

In the standard of the approval test for dust respirator certification, test aerosols are defined as air containing quartz particles of 2 microns or smaller1. However, it is well-known that the filtration efficiency of air filters depends on the size of the test aerosol particles. Alternative test aerosols containing submicron size particles will be studied for use in future approval test of dust respirators. Before searching for alternatives, characterization of currently-used quartz dust, e.g. information about size and electrostatic charge of the aerosol particles, should be determined. The currently-used approval test measures filtration efficiencies with a light scattering photometer. The photometer gives overall aerosol concentration, while Aerodynamic Particle Sizer (APS-33B, TSI Inc., St. Paul, U.S.A.) is able to give the number concentration for each particle size based on the aerodynamic diameter ranging from 0.9 to 2.0 microns. In this study, equivalent diameter was defined as the diameter at which penetration has the same value when measured by APS-33B and by light scattering photometer. The equivalent diameter for the ten filter samples for dust respirator was around 1 microns, irrespective of neutralization of the test aerosol.

Electrostatic charge on uranium ore dust

A system of four electrostatic elutriators was constructed in order to estimate the median charge on airborne uranium ore (U-ore) dust particles generated during the drilling in the open pit of the Ranger Uranium Mines in the Northern Territory of Australia. The surface alpha activity of the electrodes was measured as a function of distance from the elutriator's inlet. By analysing this data along with the measured activity mean aerodynamic diameter of airborne U-ore dust, a median electrostatic charge of about 33 electrons was calculated for a 1 μm particle. The above charge has a negligible effect on the lung deposition of U-ore dust generated by drilling of the U-ore body.

The granulometrical characteristics of a slowly‐moving dust cloud

AbstractA torn‐up road offered the opportunity to sample a dust cloud continuously at different heights during a time interval of 51 hours. In particular the granulometrical characteristics of the dust caught were investigated. It appears that if the air layer in the vicinity of a dust cloud is not too turbulent, the cloud will be clearly granulometrically stratified. The coarse material moves chiefly at the bottom of the cloud, whereas the fine material will occur both at the bottom and at the top. The experiment also shows that the higher the dust in the cloud, the worse it is sorted. Above a critical height, however, the degree of sorting increases again.The variation of the mean dust diameter d50, as a function of the height z, can be expressed in a simple semi‐logarithmic equation. The variation of the dust quantity G, as a function of the height z, can also be expressed in a semi‐logarithmic form but the correlation is higher when a power equation is used. The ratio of fine silt to coarse silt seems to vary parabolically with height.One can only speak of an optimal transport height in the case of particles > 16 μm. For finer particles, the turbulence of a normal air stream is usually high enough to carry the particles anywhere in the dust cloud, so that one can no longer speak of an optimal transport height.The granulometrical border between aeolian transport in saltation and aeolian transport in suspension lies, according to the results of the experiment, at a diameter of about 63 μm.

Card Dust Collection System Airflow Rate and Caring Rate Effects on Cotton Dust Character

ABSTRACT THE effect of the card dust collection system airflow rate and the carding rate on cotton dust character was determined. Results indicate the effect of these two variables on concentrations, large particle fraction, respirable fraction, mass median diameter and particle count of cotton dust in a card room and a remote facility used for exposing human subjects to controlled levels of dust. Results provide information to scientists involved in the design and development of facilities used for testing the effects of cotton dust on human subjects.

A Computer Model for the Cement Kiln

A dynamic model for a cement rotary kiln is proposed. It is simple enough for computer application, yet takes into account all the operational parameters actually encountered in real practice, and thus is capable of identifying the effective controlling decisions in order to realize a desired gas temperature profile, essential for optimal clinker production. The model is built in two parts. The first represents the solid-gas interchange. Its solution yields the gas temperature profile needed for good clinkering. The second represents the gas-coal dust interchange. Its solution yields the operating parameters needed to realize the desired gas temperature with a good burning of coal dust and minimal coal waste. The first part of the model is made of two and the second part of three nonlinear partial differential equations, with the independent variables being the time t and the longitudinal position x along the kiln. Boundary conditions are dictated by the operating conditions. Initial conditions are obtained by solving the static model. An example is worked out to show how the model helps to choose the coal dust input, the coal dust diameters, and other operational parameters for a good operation of the kiln. It also shows to what extent the burning of coal dust and the resulting gas temperature profile are influenced by the various operational parameters.

A correlation between the results of different instruments used to determine the particle size distribution in AC fine test dust

A specific lot of fine-grade test dust manufactured by the AC Spark Plug Division of General Motors, Flint, Michigan, was examined for particle size distribution by different investigators, using different instruments. When a particle volume measuring Coulter Counter™ and a particle shadow measuring HIAC™, or Royco™, are calibrated for particle diameter with standard spherical beads, the test particle diameters perceived by the latter instruments are 1.30 times that of the former. A πMC™ image analyzer, programmed to read particle diameter as the longest end-to-end distance, sees test dust diameters 1.33 times that seen by the HIAC or Royco and 1.74 times that of the Coulter Counter. These particle—diameter correlations are valid within the πMC diameter range of 8 – 70 μm. The πMC sees more of the smaller particles, 1 – 8 μm, than do the HIAC and Royco, but does not see as many as the Coulter Counter. The results of a SediGraph™ X-ray sedimentation apparatus agree with the results of a Coulter Counter over the Stokes diameter range of 0.3 – 80 μm, and over the Coulter diameter range of 0.4 – 70 μm.

A comparison of cotton dust sampling techniques

The standard high volume sampler, multistage cascade impactor, and modified vertical elutriators were evaluated for total cotton dust sampling. The effects of changes in performance parameters is reported. Mass median dust diameter found in four textile operations for several cotton grades are reported.

Relation of dust devil frequency and diameter to atmospheric temperature

This paper presents the results of further analysis of field data obtained on dust devils in the Mojave Desert during 1968. Emphasis was placed on the search for correlations between atmospheric properties and dust devil characteristics, specifically diameter and occurrence frequency. It was found that the temperature lapse rate γ2 in the highly superadiabatic layer from roughly 0.3 to 10 meters above the surface was the basic determinant for both frequency and diameter. As γ2 increases, frequency increases, and larger-diameter dust devils progressively appear. However, for any given diameter range, frequency increases to a maximum and then decreases with further increase in γ2. These results indicate that dust devils are generated in, and their development is initially controlled by, the γ2 layer.

A Theory on Collection Efficiency of Cyclone Dust Collector : Study on the Cyclone, 4th Report

Applying Stokes' law to the settling velocity of a dust particle, we noticed the balanced diameter of a particle and its max. value on the wall. Using Rosin's formula for the size distribution of dusts and being assumed partial collection efficiency against the dust diameter, we got many approximate formulae for the total collection efficiency, of which 1 st approximation (the critical particle diameter theory) is sufficient for the practical use. To confirm this theory the effects of inlet velocity, cyclone size, exit diameter, kind of dusts, cylinder wall length, inlet area, cylinder diameter and cone angle were measured, and we found that it coinsides with the results on the whole, although the absolute value of the collection efficiency will not be obtained only by this theory.