Excessive Humidity Research Articles

On the Condensation of Buoyant, Moist, Bent-Over Plumes

The theory of growth of dry plumes is extended to include the effects of moisture in both the vapor and liquid forms. A relation determining the point at which a moist plume first condenses is derived. Numerical solutions of this relation indicate that, under most atmospheric conditions, condensation either occurs very close to the stack or not at all. A method for predicting whether or not condensation will occur for arbitrary conditions of atmospheric relative humidity and initial temperature excess and relative humidity of the plume is given. The special case where the plume is initially saturated, corresponding to cooling tower effluents, is considered in more detail.

Use of Evaporative Cooling for Broiler Chicken Production in Areas of High Relative Humidity

ALTHOUGH evaporative cooling to reduce high summer temperatures in poultry houses is widely used in the arid West and Southwest, the practice has not been used extensively in the more humid Southeast. With the trend to more tightly enclosed houses in the South and to more mechanical ventilation, there is increased interest in the use of evaporative cooling in humid areas, even though it is known that the potential cooling effect is less in humid areas.The reluctance to use evaporative cooling in high-humidity areas may be because it is generally recognized that excessive humidity in poultry houses may result in decreased performance of the chickens. Winn and Godfrey (1967) classify humidities above 80% as "too wet," and found that as temperature goes above 26.7°C, high relative humidities have an adverse effect on productive performance. Drury et al. (1968) got significantly better weight gains in two of three…

The restriction of Cladosporium fulvum and Botrytis cinerea, attacking glasshouse tomatoes, by automatic humidity control

SUMMARYDecreasing periods of atmospheric humidity in excess of 90 and 75 % r.h. by automatic control decreased the incidence of C. fulvum and B. cinerea and sometimes increased tomato yields. The desired value of humidity was not always achieved but nevertheless environments which were both physically and biologically different were obtained with humidistats set at 90 and 75 % r.h. in glasshouses maintaining two temperature régimes–20 °C day and night, or 20 °C by day and 13 °C at night.Less B. cinerea and C. fulvum occurred on tomatoes grown constantly at 20 °C than on those grown in conditions with lower night temperatures. In the latter regime the end‐of‐season incidence of C.fulvumvas decreased from 25.0% where humidity was not controlled to 2.8% and 0.0% where humidistats were set at 90 and 75 % r.h. In the same conditions the proportion of blemished fruit damaged by B. cinerea decreased from 2.6% to 1.6% and 0.2%.

The emission of corrosive vapours by wood. I. Survey of the acid‐release properties of certain freshly felled hardwoods and softwoods

AbstractThe importance has been assessed of various factors responsible for the release of corrosive vapours from certain freshly‐felled hardwood and softwood species on exposure to high humidity and temperatures in excess of 30°. Variables studied include (i) season of felling, (ii) differences between sapwood and heartwood regions, (iii) initial acid content of the timber on felling, (iv) rǒle of non‐volatile extractive components in catalysing release of corrosive vapours and (v) inhibition of enzymic reactions by mild chemical sterilisation. Although the release of volatile acid is closely related to the loss of bound acetyl groups from the wood substance, indicating autohydrolysis of acetate in the cell wall material, the vapour corrosivity of a timber species is not directly related to its bound acetyl content. The presence of very small free acetic acid contents (0.01—0.03%) in some freshly‐felled undried woods is shown to play a significant rǒle in promoting rapid release of corrosive vapours by the woods (e.g., sweet chestnut and oak). Sterilisation of sweet chestnut and oak with propylene oxide vapour at ambient temperatures markedly reduces, but does not completely eliminate, release of corrosive vapours by these woods. An accompanying reduction in the proportion of bound acetate groups hydrolysed in the cell wall substance may indicate that the release of volatile acidic products from wood is in part due to a microbiological hydrolysis as well as chemical hydrolysis.

Control of Hassock (Deschampsia caespitosa[L.] P.B.)

ON many grasslands and pastures along the south coast of the Baltic Sea hassock has been playing an increasingly important part in recent years. Areas with excess humidity of soil are sometimes heavily infested. Lack of manpower has led to a decreasing care of the drainage system. Moreover, the reduction in the number of horses, which formerly kept hassock short, has favoured the spread of this grassland weed.

The effect of the mechanical properties of the molecular network on the wool-water isotherm

The present position of theoretical investigation of the water-content versus relative humidity isotherm is briefly indicated. Previous workers have anticipated an effect on equilibrium water-content arising from the mechanical properties of the keratin network. Such an effect is reported for supercontracted wool fibres and for reduced and S-methylated fibres, for which an increased saturation water-content is observed. In the case of S-methyl wool, saturation water-content shows little or no dependence on the number of disulphide cross-links, however it does depend on the number of S-methyl groups present. The results are considered in terms ofFlory-Huggins solution theory, and it is indicated that this theory can be usefully applied for relative humidities in excess of 85%. In normal wool “solution” absorption is permitted only in the noncrystalline component, but in supercontracted wool or S-methyl wool takes place in both components. Even when saturation water-content is greatly increased the isotherm is not appreciably changed below 85% R. H., indicating that no additional sites for strong binding of water become available; apparently all such sites are accessible in normal wool at approximately 85% relative humidity.

Influence of temperature and relative humidity on the photographic response to Co60 γ-radiation.

At relative humidities close to a hundred percent, bare film packets are unsatisfactory for personnel dosimetry, regardless of temperature. Sealed polyethylene bags afford considerable protection from excessive humidity. (auth)

On the Pressure Dependence of Microwave Crystal Rectifiers (Correspondence)

During the past couple of years, as a result of government interest, silicon microwave crystal rectifiers have not only decreased their noise figures but also have increased their resistance to adverse environments; i.e., high burnout, high temperature, excessive humidity.

A New Roll-Film Dryer

Roll film has become an established feature of serial roentgenography (1–3). Developing, fixing, and washing have been relatively simple with the Fairchild-Smith motor-driven x-ray roll-film processing unit. Drying, however, because of the length of the film, up to 75 feet, has been difficult, requiring careful hanging and separation to prevent sticking (4). Standard hot-air dryers are ill suited for this purpose because of the long time required for the drying, and the necessity of draping and looping of the roll film, demanding constant attention to prevent scratching and falling. Recently, a new drying apparatus has been made available.2 Mechanism of Dryer Parts: The dryer is sturdily constructed of stainless steel and built to process films of varying widths up to 12 inches. Essentially, it is of simple design, consisting of four main parts: a 1/3-horse-power, 60-cycle, 115-volt motor; a spring-type 60-minute timer; three 15-ampere coil heater units; and two fans. The motor has a dual purpose: it provides, through a gear arrangement, transport of the film and furnishes the power for the twin fans. The blowers are arranged on either side, and a baffle forces jets of warmed air to circulate on both sides of the film. Hot air is generated by the three heating units located at the bottom of the dryer. The timer can be pre-set for the estimated drying period and automatically shuts the unit off. Operation: The operation is simple. The Fairchild-Smith processing x-ray roll film developing device is attached to the dryer (Fig. 1). The “leader edge” is detached from the reel and is drawn by hand into the drying chamber. The dryer is then turned “on.” The loading strip is allowed to dry, which usually takes half a minute. It is then attached to the “take-up” spool with a strip of adhesive (Fig. 2). The timer is set according to the length of film to be dried. For a full 75-foot roll at a speed of 22 inches per minute, the drying time is fifty minutes. In case of excessive humidity, the speed of film transport may be slowed. There are four speeds, with a maximum of 22 inches per minute. Adjustment to the desired rate of film transport may be had by pre-setting the lever drive at the clutch. Discussion The roll-film dryer herein described has had constant use during the past year. A total of 150 rolls of film of approximately 75 feet each have been processed. Film varying from 9 1/2 to 12 inches has been used without mechanical difficulties. Because of the compactness of the unit (25 × 25 × 20 inches), it occupies only a small corner of the dark room. Considerable time has been saved in the actual film drying period and, more important, the automatic feature obviates the need of attention. In no instance was there failure to secure a dry, finished, and unmarred product. Summary and Conclusion A new automatic roll-film dryer is here described.

Los of charge in B.D.11 chambers due to mechanical shock.

It is a common experience that B.D.11 ionization chambers, when used for a routine protection service, are liable to suffer from spurious charge losses. These are usually put down to causes such as the presence of hairs or excessive humidity, although we have found that ionization chambers stored in saturated air for several hours do not in fact lose charge as a result; but we have found that chambers do lose charge when subjected to mechanical shock.

Medical problems encountered in undersea craft.

The effect on man's life in abnormal spheres of environment, for which he is more or less not physiologically adapted, is portrayed rather dramatically by service in that portion of the armed forces devoted to operation of undersea craft. In order to appreciate the general living conditions in undersea craft, it would appear appropriate to consider briefly some of the circumstances which come to bear on a person's day to day existence aboard a submarine. Prolonged residence in specialized craft, such as submarines, where sunlight is nil and outside ventilation is reduced to only part of the day and where there is close association in the sleeping and working spaces, obviously is fraught with ideal conditions for the spread of disease. The ever present excess humidity additionally promotes discomfort and propagation of disease by enhancing the effect of either tropical or frigid temperatures. Life aboard submarines is monotonous for long

Effect of Excessive Humidity on the Resistance of Citrus Plant to Sun Scorch

Effect of Excessive Humidity on the Resistance of Citrus Plant to Sun Scorch

The Effect of Deficiency and Excess in Rainfall upon the Hickory Bark Beetle

An epidemic of the Hickory Bark-Beetle started in Syracuse in 1912 and has extended to the present time, with a decided checking in 1915. This was preceded by semi-drought conditions over a period of several years before the epidemic started. While the trees were undoubtedly affected, as is shown by a study of the rings of growth, the indirect effect through the lessening of the vitality of the trees is not sufficient to account for all the phenomena. The greatest effect was the more direct one upon the insects themselves, as the deficiency came during the summer months. A deficiency at this time is beneficial to both adults and larvae, and an excess, as in 1915, acts as a distinct check. When the adults are active, continued rain kills many while feeding and establishing their burrows and also checks egg-laying. Excess rainfall, humidity and cloudiness kills the larvae because it produces an excess of water in the plant tissues and this is set free into the larval mines. Deficiency in rainfall has a beneficial effect upon both adults and larvae. This may be put to practical use. It is known that there has been a deficiency in rainfall extending over several years, an intelligent lookout can be made for the first signs of undue increase of dangerous forms and these can be controlled before they reach epidemic proportions.