Requirements for clothes

 

When you design clothes you must consider a variety of requirements that are divided into aesthetic, sanitary and engineering [1, 2].

One of the main requirements that determine the quality of the clothes are aesthetic requirements. Clothing should be beautiful first of all, as it plays an important role in shaping the external appearance of a person. The beauty and expressiveness of the garments are achieved through the art of composition*. Clothing, made in the context of mass production, are requirements of manufacturability and cost structures. Each garment must meet hygienic and technical requirements characterizing the garment according to its purpose.For example, thermal protective clothing must have a high thermal resistance, raincoats - waterproof, linen and summer clothes - good air and vapour permeability, hygroscopicity and etc. Clothes of all kinds should have a certain strength, durability, stiffness, weight, etc.

Clothing covering more than 80% of the body surface is an effective means of protecting the human body from the adverse effects of the external environment and creates around the body of a human artificially regulated microclimate.

The main parameters of the clothing microclimate air that affect human health, according to [3], temperature, relative humidity and carbon dioxide.

Created by the clothing microclimate on the parameters is significantly different from the parameters of the environment and is characterized by a constant and variable in a relatively small range of temperature, low relative humidity and low air movement [3].

The most important function of clothes is to maintain a constant body temperature through any change in ambient temperature**. A constant average temperature of the surface of the body in a dressed person, scientists-hygienists [3] consider 33'S. This temperature corresponds to the feeling of comfort (wellbeing) in humans and is set in the result of thermal balance between human body and environment when the quantity of heat produced in the human body - heat production corresponds to the amount of heat given to the external environment - heat transfer.

P. A. Kolesnikov [4] are obtained hygienists curves, gives an indication of heat transfer (heat loss) differently-dressed man when you change the room temperature (Fig. V-1).

As can be seen from the figure, the heat loss dressed person compared to undressed much less and depend on the thermal resistance of clothing. Reducing heat loss garment contributes to maintaining a constant skin temperature and comfort sensation.

For example, if you change the outside temperature from 20 - 22 to 9 - 12'C (10'C) temperature of the skin under a woollen suit decreased from 32.6 to 30.6'C; i.e., only 2.0' [3].

The amount of heat produced by the human body, (heat production) depends on many factors, including muscular activities of man. The least amount of heat is produced during the rest, the greatest - when you perform heavy physical labor.

P. A. Kolesnikov [4] gives the following data on heat production under different conditions of human activity.

 

Activity heat production

kcal/h W

Sleep, calm lying in bed 70 81,5

Seat.............. 75 - 80 87,3 - 93,1

Work in the science lab .. 120 - 140 140 - 163

Light physical work (typist, etc.)... 120 - 170 140 - 198

Walking on a flat road at a speed of 3 km/h ... 150 - 170 175 - 198

Walking on a flat road at a speed of 5 km/h.... 230 - 270 268 - 315

Moderate physical work (caster, Metallist, Shakhtar Donetsk)... 170 - 220 198 - 256

Heavy physical work (digger, loader, logger)..... Over 220 Over 256

Mountaineering ........... 670 - 970 779 - 1140

 

Heat transfer through clothing to the environment (heat emission) is performed in the following ways: by conduction (conduction), convection, (conduction), radiation (radiation), evaporation of sweat [4]. Generally, heat transfer occurs simultaneously through three ways or any two of them.

The ratio of different types of heat transfer is fickle and changes depending on temperature and air movement in the external environment, human activity, etc.

So, through clothing materials heat is transferred mainly by conduction.

Heat transfer by convection and radiation occurs in the air strata, and the outer surface of the clothes [4].

At high ambient temperatures, and also when performing hard physical work increases the heat of vaporization.

Moisture continuously evaporates from the surface of human skin to the environment. This evaporation occurs via known physical laws, due to the difference between the vapour pressure of the liquid in the human skin and the surrounding air.

In a relaxed state and the person in normal conditions, if the clothing conforms to the outside temperature, all released by the body moisture is absorbed by the materials of clothing, and then evaporates into the environment and the body remains dry***.

Through the skin continuously released also carbon dioxide is absorbed and oxygen, which suggests the presence of not only lung, but also skin breathing.

The impact of carbon dioxide and absorption of oxygen through the skin usually increases with enhanced muscle activity with an increase in the ambient temperature. According to the data given in the literature [2], in the adult, when the outside temperature is 24 - 25' C while the rest was allocated 255 mg carbon dioxide per hour, when working up to 365 ppm, and at a temperature of 40' C, respectively 625 and 945 mg per hour.

In ambient air the concentration of carbonic acid does not exceed 0,03 - 0,04%. There is evidence that the content of carbon dioxide in the air clothing more than 0.8% of the adverse effects on the human body [3].

To remove moisture and carbon dioxide materials clothing must have good air and water vapor permeability.

When there is insufficient air and vapor permeability of clothing materials (mantle fabrics, of synthetic fibers, fabrics with special impregnation, reducing their air and water vapor permeability, etc.) moisture and carbon dioxide linger in the clothing space and one loses the feeling of comfort.

New synthetic materials and coatings are widely used for the manufacture of special protective clothing production, the operation of which there is increased production of moisture and carbon dioxide. For such products it is necessary to provide a constructive means of intelliremote clothing air.

Interestingly this problem is resolved by the laboratory production of clothing TSNIISHP [5]. When creating a waterproof special clothes were made vent holes on the back, shelves, sleeves, half pants, etc made in the seams coquettes in the form of folds and oblachnykh holes (Fig. V-2).

At high temperatures, the hard work, quick walking or running, and when used inappropriately warm clothing is overheating of the body and the surface of the skin stands out not only vapor but also condensed moisture in the form of sweat****. To remove sweat from the body clothing materials should have a high hygroscopicity.

To prevent excessive sweating when you are designing clothes you must know the ways and means of creating clothes with the best indicators of microclimate for different conditions.

At low temperatures, the clothing performs primarily a protective function, delaying the return body heat to the external environment. Design of sustainable clothing that protects the body from cold, for various climatic and production conditions is a very challenging scientific problem.

The process of heat exchange between the human body and the environment, flowing through the clothes, is very complex, and experimental methods of assessing thermal properties of clothing is imperfect. Therefore, a number of researchers have attempted to create analytical methods of thermal calculation of clothing.

The greatest practical and theoretical interest is the method developed by G. M. Kondratiev [6] and also described by P. A. Kolesnikov [4] the method of M. I. Budyko.

G. M. Kondrat'ev gives an approximate thermal design of clothing, linking the human heat production (metabolism) with the influence of the environment, provided that clothing provides to the body a feeling of comfort*****.

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* Consideration of composition of clothing is the subject of a special course of artistic design of clothing.

** Freezing temperatures in Antarctica reach - 88'S and the average July heat of the steppe regions of Central Asia +30'C [4].

*** In these circumstances, the so-called dry cooling of the skin surface the man is about 40 - 70 grams of steam (at a temperature of 20 - 26'C) [4].

**** In these circumstances, the so-called wet cooling evaporation of sweat is the primary means of heat transfer.

***** For the comfort criteria adopted, the average temperature of the skin.

 

LITERATURE

 

1. Merchandising of industrial goods. Gostorgizdat, vol. 2, 1952.

2. Rusakov S. I. About the requirements for clothes. M., 1958.

3. The problem of studying of hygiene of clothing. Izd-vo AMN SSSR, 1953.

4. Kolesnikov P. A. Thermal insulation properties of clothing. Publishing house "Light industry", 1965.

5. Arlovski V. I., Dotsenko G. I., Savchuk T. I., Antipov G. N. New models of workwear. A collection of abstracts of research works TSNIISHP, 1964, No. 28.

6. Kondrat'ev, G. M. Approximate calculation of thermal clothing. Proceedings of the TSNIISHP, 1957, No. 6.