Vertical elutriator

As measured by the vertical elutriator cotton-dust samples. 

Lint-free dust as measured by the vertical elutriator cotton-dust sampler described in the Transactions of the National Conference on Cotton Dust, p. 33, J.R. Lynch (May 2, 1970). 

Both washed and unwashed cottons were processed through a blender feeder, a No. 12 horizontal opener, and a two-beater picker and made into picker laps. The carding was conducted in our model cardroom at 18,2 kg/h, and dust levels were determined by use of vertical elutriators. The cottons were spun into 19.7 mg/ m yarn of 38.2 twist factor at 13000 rpm spindle speed in a 4536 spindle-hour test. 

The prototype cotton-dust analyzer used in the initial study was designed to measure dust smaller than 100 pm, whereas a vertical elutriator in a card room measures only the dust that is smaller than about 15 pm. Differences in particle size distributions of dust from various types of cotton would likely affect the relationship between the two dust measurements. Therefore, we deemed it necessary to investigate the use of sizing screens with smaller openings i.e., openings whose size approximated the maximum size of particles collected by a vertical elutriator. The purpose of this report is to describe additional modifications to the cotton-dust analyzer and to present data on the performance of the machine when 17-, 50-, and 100-pm sizing screens were used. 

A Standardized Method for Vertical Elutriator Cotton Dust Sampling... 

The alternative Instrument used was a Portable Continuous Aerosol Monitor (PCAM) manufactured by ppm, Inc., and dust concentrations measured with the PCAM were 5-15% lower than values obtained with standard vertical elutriators. Calculations and examples for TWA exposures, equivalency tests, and vertical elutriator coefficients of variation are included. 

Cotton dust sampling is a plant site test, normally involving unsophisticated field equipment, ever-changing plant conditions, and technician-level labor in performing many functions. However, with adequate equipment and attention to technique, we have found that good quality data can be obtained for each survey. The purpose of this paper is to share with you some of the instrumentation, equipment modifications and techniques we have studied and employed to obtain vertical elutriator (VE) data with average coefficients of variation less than 10%. 

Vertical elutriator schematic. (Drawing courtesy of the National Cotton Council)... 

After all data has been compiled to show TWA values this information is then shared with employees using a computerized employee exposure form. This concludes the task of dust measurement by means of the standardized vertical elutriator method. 

Avg LVE = Avg Dust Concentration from Multiple Large Vertical Elutriators. 

Figure 9. Schematic of PC AM equivalency testing rig showing the relationship of large vertical elutriators to PC AM small vertical elutriator.

Large Vertical Elutriator Data (Coefficient Of Variation With 3 LVE s)... 

PCAM s, and with vertical elutriators, and some of these results have been published (4,, 7 ). The CAM and PCAM methods have proven to be quite powerful for quantitative determination of x, and other constituents of respirable dust C ). These determinations have been used to evaluate feasibility of engineering controls or to establish sound data to be used to possibly subtract the x, component from apparent cotton dust levels. 

The basic instrumentation in the present work is a Royco Model 225/518 High Concentration Particle Counter. The location of the air inlet and light sensing unit of the instrument in the card room has been described previously (2). The inlet was fitted with a vertical elutriator preseparator designed to prevent particles >15 vin aerodynamic diameter from entering the light sensor. Thus the collection efficiency of this instrumentation as a function of particle size should be similar to that of the Vertical Elutriator Cotton Dust Sampler. 

The algebraic calculations of the distribution parameters included all cells of the histogram while those obtained from the cumulative plots were sometimes based on only a part of the cells. When the distribution was multimodal, the latter calculations included only the values from the distribution with the smaller diameter, and no attempt was made to adjust the percentage count for the number of points in the larger dicuneter distribution(s). Other factors reported are the number of particles per 0.1 ft, the dust concentration measured with the Vertical Elutriator Cotton Dust Samplers (VE), the nature of the cumulative plots, and for multimodal distributions, the percent of particles in the distribution with the smaller dieuneter. 

Apparently Fischer (13) is the only investigator studying respirable airborne dust(collected by vertical elutriator, i.e. 

In the other study. X-ray fluorescence spectroscopy was used to analyze trace element concentrations by observing dusts on 37 ram diameter cellulose acetate filters (20). Twenty-three elutriator and twenty-three area samples from 10 different bales of cotton were analyzed. The average fraction of total dust accounted for by the elements analyzed was 14.4% amd 7.6% for vertical elutriator and area samples, respectively. Although the variation in absolute quantity of atn element was high, the relative abundance of an element was consistent for measurements within a bale. Averaged over all the samples analyzed, calcium was the most abundant element detected (3.6%), followed by silicon (2.9%), potassium (2.7%), iron (1.1%), aluminum (1.1%), sulfur (1.0%), chlorine (0.8%) and phosphorous (0.6%). Other elements detected in smaller aunounts included titanium, manganese, nickel, copper, zinc, bromine, rubidium, strontium, barium, mercury amd lead. 

Much of the variation in absolute quantity of an element was shown to be due to variation in dust concentration. The correlation coefficients of linear regression models predicting the concentration of calcium and silicon from the vertical elutriator dust concentration were 0.89 and 0.79, respectively. 

Recent reports suggest that a significant portion of the dust measured by a vertical elutriator in a card room may be due to solids in humidifier water (23,25,43). Undoubtedly, much of the inorganic matter found in the model card room dusts arises from this source. 

Table V shows a typical profile of elements in dust on a vertical elutriator sample.

A Typical Profile of Elements Measured by X-Ray Fluorescence in Cotton Dust Collected by a Vertical Elutriator on a Cellulose-Ester Filter (20)... 

Dust Concentrations Measured in a Textile Mill with Vertical Elutriator Samplers as a Function of Variation in Water in Humidifier System. (25)... 

Vertical elutriator on model card room determinations machine., no dust suppression, systen... 

Textile mill dusts investigated include samples collected using a vertical elutriator cotton dust sampler, seunples of fine dust separated mechanically from carding filter cake material, Scimples collected on electrostatic precipitators in a card room, coarse condenser trash from a card room, and weave room dusts. 

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