Robert M. Bethea

Variation in trash composition in raw cottons

Raw cotton from 4 machine picked varieties and 2 machine stripped varieties is examined by stereomicroscope and bright-field microscopy for presence of plant trash(bract, leaf, stem, seed, boll, and weed fragments-size range 841-2000mum) that gives rise to cotton dust during yarn manufacturing operations. Bract was found to be the major trash component in all raw cottons examined. Cotton leaf and non-cotton weed materials were also major trash components in most raw cottons.

Botanical trash present in cotton before and after saw-type lint cleaning

The % by weight content of leaf-like, stem, boll, seed, and weed materials sifted (3360 mum greater than particle size greater than or equal to 595 mum) from visible wastes of the Shirley Analyzer was determined for a lint sample taken after ginning but before cleaning and for a second lint sample taken after one stage of saw-type cleaning. The % by weight content for bract and leaf increased with decreasing trash particle size. The content of cotton seed coat fragments decreased with reduction in trash particle size. Approximately 1/4 of the botanical wastes consisted of weed materials, including grass particles. Lint cleaning was ineffective in reducing the % by weight content of leaf-like trash. Some selective removal of stem trash occurred as a function of lint cleaning.

Comparison of Hydrogen Sulfide Analysis Techniques

A summary and critique of common methods of analysis for H2S is presented. The procedures described are: reflectance from silver plates and lead acetate-coated tiles, lead acetate and mercuric chloride paper tape, sodium nitroprusside and methylene blue wet chemical methods, infrared spectrophotometry, and gas chromatography. Pertinent details included for each method are type (continuous, semicontinuous, averaging), lower detection limit, range, known interferences and suggestions for their elimination, and appropriate instrument parameters as wavelength, flow rates, temperature, and sample size. The limitations of each technique are clearly described, as are the advantages, in such a manner as to aid the user to select proper instrumentation for his analytical requirements.

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.

Endotoxin Content in Cottonseed Oil Mill Dust

The objective of this study was to quantify the amount of endotoxin present in respirable dusts collected in cottonseed oil mills. The level of endotoxin in workplace air exceeded 0.5 µg/m3 in about 30% of the examined samples. The amount of endotoxin found in the dust varied over two orders of magnitude from 0.01 µg to 1.3 µg per mg of vertically elutriated particulate. The endotoxin contamination of cottonseed oil mill dust varied both between and within mills and was not consistently related to the amount of dust captured by the vertical elutriator cotton dust sampler.

Use of a fluorescent tracer technique to study the botanical trash composition of cotton dust

Fluorescently dyed leaf trash of known particle size distribution (XN=66 µm) was prepared and blended into raw cotton which was subsequently processed in a model cardroom. The XN of the added leaf tracer collected in undercard and Pneumafil filter wastes was reduced to 64 and 54 µm, respectively. The XN of vertically elutriated leaf tracer was somewhat less (3.8 µm) than the XN (4.4 µm) of a small number of potentially respirable particles present in the raw leaf tracer. The fluorescent tracer technique, as applied to carding, offers a direct means of comparing the friability of the different botanical trash components found in raw cotton.

Evaluation of a fluorescent dust tracer technique in cotton ginning

A technique employing a fluorescent tracer for following the break-up and dispersion of cotton trash has been developed. Senescent cotton leaves were treated with a fluorescent dye, pulverized to match the same particle size distribution as naturally occurring leaf in raw seed cotton and uniformly incorporated into the seed cotton mass prior to processing in a saw-type micro-gin. A control lot was similarly processed, excluding any dye. Airborne samples collected from the major fugitive dust emission points by standard techniques, macro trash samples collected from four locations, and the final condensed lint product clearly show that the use of such tracers is not only feasible but highly useful in determining the locations where respirable dust is emitted. From the fraction of labelled tracer material found at any site, the relative amounts of both total and respirable dust emissions of that plant component can be estimated from the known masses of dyed material added to a given mass of seed cotton. Estimates of the relative severity of fugitive dust emissions from various processing steps in a cotton gin are presented based on vertical elutriator, high volume and multistage cascade impactor sampler data.

Occupational dust exposures in West Texas cotton gins.

Total and elutriated dust concentrations were measured by four methods for typical ginning situations. Total and elutriated levels were 0.73 and 0.47 and 0.59 and 0.26 mg/m3 per bale/hr by the gin stands and bale press, respectively. Limited data show the corresponding mass media diameters are 9.2-14.8 and 9.6-18.5 micrometer.

Effect of chemical defoliation on leaf and bract content in raw cotton.

Chemical defoliants are applied to about 40% of the U.S. Cotton acreage as a harvest-aid practice prior to machine picking. Raw cottons derived from defoliated and nondefoliated fields were examined for content of bract and leaf trash Chemical defoliation lowered, but did not remove, leaf as a major trash component. The content of bract was unaffected by this harvest-aid practice. The histamine content in green leaf trash was 10X that found in nongreen leaf trash.

Note On The Collection of Lint Fly by Wet Impingement

A combined water scrubber-impinger was used to control lint cleaner effluent from machine-stripped short staple (11/16-13/16 in.) cotton because of its high efficiency and low pressure drop. The 8 × 4 × 4 ft rectangular scrubber could handle a maximum of 8000 CFM entering air at 80°F, 20% relative humidity and 0.7 g particulates/m3 with a 1-sec residence time at a maximum pressure drop of 0.5 in. of water across the chamber. Water to the chamber’s 6 doublespray and 2 single-spray nozzle taps was supplied from recycle and makeup sources at pressures of 7.5–30 psig with total flows of 21.8–31.1 gpm depending on number of nozzle taps in use. These sprays effectively wetted the particulate- laden air and provided enough water to wash the collected particulate matter down the chamber walls. The four WR-10 nozzles used at the base of the scrubbing chamber provided fine conical spray patterns co-current with the air flow. The two sets of four F-20 nozzles used in the center portion of the chamber provided coarse...