Technical parameters of sleeping bag

A general temperature scale consists of three data.

Low temperature: refers to the extreme temperature of sleeping bags, which only means that such a low temperature will not freeze you to death, and it is hard to say whether you can fall asleep or not. Below this temperature, it is dangerous for users.

Comfortable low temperature: refers to the ideal temperature for comfortable use of sleeping bags. At this temperature, people can sleep very comfortably, and will not be unable to sleep because of the cold.

High temperature: refers to the upper limit of the temperature range, beyond which users will be unbearable hot.

There are two ways to identify the comfortable low temperature on a sleeping bag. 1 means to identify an absolute temperature, such as-10 degrees, which means that the comfortable low temperature of the sleeping bag is-10 degrees; One is to indicate the temperature range, from red to green or blue, for example, red starts at 5 degrees, 0 degrees transitions to light green, and transitions to dark green at -5 degrees. The meaning of this temperature is: 5 degrees warm, 0 degrees suitable, and it feels very cold at -5 degrees. The comfortable low temperature of this sleeping bag is 0 degrees. It should be noted that comfortable low temperature is only a relative concept. Sleeping bag products have no industry associations and industry standards, whether at home or abroad. Some big brands and research institutions label their products as comfortable and low temperature according to laboratory tests and field experience. This temperature is for reference only and will vary from person to person and from environment to environment. Generally speaking, sleeping bags originated in Europe and America are not suitable for Asians on the temperature scale, because Europeans have higher cold resistance than Asians, so we should pay special attention when choosing them.

Low comfortable temperature is generally defined as the low temperature of the human body during 8 hours of continuous warm sleep; Limit temperature refers to the low temperature at which sleeping bags can protect the human body from losing temperature. Generally, it refers to the temperature at which the human body does not keep warm after sleeping for 6 hours continuously and will not cause dangerous harm to the human body.

The human body generates heat through metabolism. When we feel warm, it means that the heat generated by our bodies is equal to or greater than the heat lost to the surrounding environment. We lose heat through the following ways:

-Heat conduction in contact with the body, especially the ground below the body.

Convective air around the body and air exhaled when breathing.

-Sweat on the skin surface evaporates.

-Infrared thermal radiation of human body

For a person who is sleeping, the thermal energy conduction of body contact and air convection are the major ways of heat loss. A simple energy balance formula is used: the thermal energy generated by the body = the thermal energy lost by the body through conduction, convection and radiation.

Conduction: The ground is the main heat loss factor. Although sleeping bags can be improved, sleeping mats between sleeping bags and the ground are more important. Choosing a sleeping pad with high thermal insulation coefficient can reduce heat conduction to the ground.

Convection: This is the main factor of sleeping bag heat dissipation. Thick sleeping bags can be used to isolate more still air around the human body.

Breathing: In a cold environment, a lot of heat is emitted through breathing.

Evaporation: Sweat evaporation is the main way to cool the human body, but when sleeping in a cold environment, sweat evaporation will be rare.

Radiation: only accounts for a small part of the heat lost by the human body.

The function of sleeping bag is only to keep as little heat as possible, while the human body in sleeping bag constantly generates heat to keep warm. Different individuals and situations generate different amounts of heat. All sleeping bag temperature standard systems are based on a standard human body, but such a standard human body basically does not exist. A sleeping human body has about 75- 100 watts of thermal power, which is converted into about 47-55 watts per square meter according to the surface area of the human body. The energy generated by metabolism is very complicated, which is related to age, sex and even the amount of fat under the body, but generally speaking, a strong young man always produces far more body heat than the elderly and women. The feeling of cold is related to age and experience. Novices generally feel colder than experienced climbers. People who often work outdoors feel warmer in a cold environment than those who often work in an office.

Generally speaking, after the age of 25, fat people feel less cold than thin people. Fat people always say that their metabolism is slow. More precisely, fat people eat more food than they consume. The metabolism of thin people is relatively balanced, which means that the food they eat can basically be consumed. When food is scarce, fat in the human body can be metabolized to produce energy. Outdoor activities such as mountaineering and hiking often make the human body consume far more energy than food, so polar and alpine exploration activities need more heat. Fat people can burn the fat stored in the body into energy, and fat people have a thicker natural insulation layer than thin people, so fat people are more resistant to freezing than thin people. In addition, women generally feel cold more easily than men. On the comfortable temperature scale of sleeping bags, women are often about 5℃ higher than men. Because metabolism is related to age, old people produce less energy than young people, so they are more likely to feel cold. Healthy men aged 65,438+06-24 are in a period of vigorous metabolism, and the heat energy generated by their bodies is much higher than the heat energy lost, which is about 5℃ lower than that of the elderly in the comfortable temperature standard of sleeping bags. For children, it is difficult to define the temperature scale of sleeping bags because there is no mature metabolic system. In history, most of the research on sleeping bags focused on soldiers, outdoor trainers, mountaineering guides, mountaineers and other people with rich outdoor life experience, aged between 18-40 years old. But in fact, most outdoor activists usually live in cities, work in offices with central air conditioning and drive around. These lifestyles reduce the adaptability of ordinary people to the cold environment. If people who have lived in the city for a long time suddenly go into the wild environment, hard hiking or even high-altitude mountaineering will soon run out of energy, and the heat generated by tired bodies will be reduced, making people feel cold more easily.

In order to establish the temperature grade of sleeping bags, the prototype of sleeping bags before commercial production should be tested outdoors, and the testers are often people living outdoors, such as soldiers and mountaineering guides. They need to test in the outdoor environment for several weeks, and then give the manufacturer advice on the comfortable temperature and extreme temperature of the sleeping bag.

For sleeping bag manufacturers, testing sleeping bags requires temperature, wind speed, humidity, wind speed, clothes and other conditions, and it is difficult to face various environmental and climatic conditions like mountaineers. The general test can only be based on a certain temperature and humidity in an ideal environment, but the test results are quite different from the actual use. In order to make the test results closer to the real use environment, all brands have set up climate laboratories to control the physical conditions such as temperature, humidity and wind speed in the artificial environment, and test the sleeping bags in the corresponding climate, so as to obtain the temperature scale coefficient which is more in line with the real use situation. With the progress of science and technology, computers and various detection methods are constantly improved and perfected, and infrared thermal imaging system is also applied in sleeping bag detection. According to infrared thermal imaging, the heat dissipation of human body in sleeping bag can be clearly judged, and the red area indicates that the heat emitted is more than the corresponding blue area, so the design of sleeping bag can be improved accordingly.

Some important sleeping bag standards

-BS 4745- 1984 textile thermal insulation standard

-ISO 5085 standard for thermal insulation of textiles

-EN 3 1092 thermal insulation standard for textiles

-ASTM F 1720-96 American sleeping bag standard is based on real-time sweating human thermal model test.

-G08-0 13 French sleeping bag standard

-EN 537 13-2002 eu sleeping bag standard

In April 2002, the new European standard EN 13537 passed CEN verification and became a necessary condition for the calibration of sleeping bags. The sleeping bag comfort temperature standard based on EN 13537 is more reasonable than the previous commercial practice, and in the next few years, the proportion of sleeping bags marked with EN 13537 will increase to 50% in outdoor stores. In addition, after 2005, the proportion of sleeping bags marked with EN 13537 must reach 100%. However, in countries and regions outside Europe, the standard of sleeping bags is still marked according to traditional business practices, which brings great confusion to consumers. Sleeping bags are mainly filled with down and chemical fiber cotton, and there are also single-layer polar fleece sleeping bags.

Down: divided into duck down and goose down. Under the same conditions, the warmth retention of goose down is slightly higher than that of duck down. Down mainly has three performance indexes: 1 the index is the filling weight, such as 400g goose down sleeping bag and 1 100g duck down sleeping bag. This weight does not refer to the weight of the sleeping bag, but to the net weight of the filled down; The second index is down content. Down is composed of feathers and down. Feathers play an auxiliary role, and warmth mainly comes from fine down. The cashmere content is expressed as a percentage, for example, 80 cashmere content means that the cashmere content in 100 weight unit is 80 units. Duck down generally has a high down content, ranging from 85 to 90, and goose down has a down content of 90 to 95. The third index is the expansion of down, and the filling power refers to how many cubic inches an ounce of down has under the pressure of 68.4 grams. The higher the swelling degree of down, the better the warmth retention of down. Generally, the swelling degree of domestic duck down is about 450, and that of domestic goose down is between 450 and 600. The cashmere content of Andes geese imported from the United States can reach about 95, and the swelling degree can reach 700 to 800.

Very cheap down products are sometimes found in the market, such as 100 yuan down jacket and 150 yuan duck down sleeping bag. Such products are generally not optional. Because down has two indexes that ordinary people can't test on the spot: oxygen consumption index and cleanliness. Down needs to go through many professional cleaning and degreasing procedures. Some suppliers make finished products after slightly cleaning the primary fluff. These products can't be used at all The simple identification method is to beat the finished product with a wooden stick, which will lead to dust leakage and odor. If cleaned, the water will smell bad. Down itself is a quality product. I hope everyone can buy really good products.

Chemical fiber cotton: there are many kinds and the quality is uneven. Ordinary glue-sprayed cotton, from four-hole cotton to seven-hole cotton (concept of seven-hole and nine-hole cotton in porous cotton market: the state has no standard for porous pillows, and there is no specific requirement for porous fiber content. The number of so-called "holes" is even more exquisite. The pillow book quoted Yizheng Chemical Fiber, the authoritative fiber industry in China. Yizheng Chemical Fiber Factory, with advanced technology, only produces one-hole hollow fiber, without seven-hole and nine-hole fibers, so the market is not elegant. ), 3M Thinsulate cotton, POLARGUARD 3D/HV cotton, etc. The difference between polarguard 3d and polarguard HV is that the former has better compressibility, while the latter has better warmth retention effect. Generally, it can reach -5~- 15℃ in 3D and-15~-25℃ in HV. Like all kinds of sleeping bags filled with chemical fiber, their thermal insulation performance will gradually decrease until they can't be used, but they have an advantage that a down sleeping bag doesn't have, that is, it can still keep warm after being wet, unlike down sleeping bags that don't keep warm at all or even have negative effects once they are wet. The bulk density is expressed in grams per square meter, such as 260 grams per square meter and 320 grams per square meter. Compared with down and chemical fiber cotton, down has higher warmth retention, and its weight can be lighter under the same warmth retention. Chemical fiber cotton has relatively low warmth retention, large packaging volume and poor compressibility; Down is expensive, chemical fiber cotton is cheap; When the down is wet, it will almost lose all its warm keeping ability and it is not easy to dry. Therefore, in the harsh mountaineering environment, materials with water release and air permeability are often used as the outer material of down sleeping bags. Chemical fiber cotton has a certain degree of water repellency, maintains a certain degree of warmth retention after being wet, and has a fast drying speed; Down products have a long service life, and can be used for more than 10 years after good maintenance, while the life of chemical fiber cotton sleeping bags is only 3 or 4 years.

Polar fleece: Sleeping bags are made of polar fleece and can be used as summer sleeping bags or sanitary sleeping bags alone. It can also be used with other sleeping bags in winter to enhance the warmth effect. According to time experience, a sleeping bag and fleece sleeping bag with a temperature of -3 degrees can keep warm to-10 degrees. Feather sleeping bags have high requirements for both internal and external materials, and the lining is generally above 200T, because if the lining index is less than 200T, individual hairs will be worn out. Some good sleeping bags often use good nylon materials, and there is no wool wear out. This material is very light and feels soft when touching the skin;

External material of sleeping bag: Good down is mostly made of waterproof and breathable material, because in some extremely cold places, when getting up in the morning, small water droplets condensed from the hot air in the tent often splash on the sleeping bag, so the external material of sleeping bag should be waterproof to a certain extent to ensure the drying of the sleeping bag. Because the down sleeping bag is not easy to dry once it is wet, it will lose its thermal insulation performance, so it is necessary to use waterproof and breathable materials as its external fabric.

Artificial vacuum cotton

Features are moisture-proof, lightweight! Therefore, in a humid environment, it is best to choose an artificial vacuum cotton sleeping bag. Avoid wetting the sleeping bag, or sleep will be seriously affected.

Feather material

Down sleeping bags are light and warm, but they must be kept dry. Once it gets wet, it not only loses its heat insulation effect, but also is difficult to dry.

Camping bag

It can replace some functions of tents to keep you dry, but in the long run, it is not as practical as tents, because tents are also places for cooking and daily activities. Put your sleeping bag in a small bag, put it in a compression bag, and reduce the volume to a small size. In order to keep the sleeping bag clean, you can put an epithelial pad or poncho under it.

Internal and external materials

Ordinary cotton sleeping bags are made of polyester or nylon, and polyester nylon cloth is different in density and texture, so I won't go into details here. Down sleeping bags have high requirements for both internal and external materials, but only nylon material with a density of more than 230T can ensure cashmere prevention. The density of many nylon fabrics in China is not enough to prevent cashmere, so it is unscientific for manufacturers to use coatings to prevent cashmere. Because the inner and outer materials of down sleeping bag need to have good air permeability, otherwise the moisture emitted will gather in the sleeping bag, which greatly reduces the warmth of down. High-woven pure cotton or polyester cotton can also prevent cashmere, but it is heavier and has poor compressibility, and is generally not used for high-grade sleeping bags. There are three kinds of common sleeping bags, mommy, envelope and beer barrel. Mami style is also called mummy style or mummy style. This kind of sleeping bag has wide shoulders and narrow feet, with a shoulder width of 75 to 85 cm and a foot width of 35 to 45 cm. Mami sleeping bag is a kind of sleeping bag shape which can achieve good warm effect under the same weight, and is suitable for use in cold seasons. As the name implies, the width of the envelope sleeping bag is the same as the shoulder cloth and feet, like an envelope. This kind of sleeping bag is relatively loose, suitable for people who are warmer and bigger in summer. Hybrid sleeping bags are a combination of the first two, most of which are envelope sleeping bags and a mommy hat.

The internationally popular sleeping bag is a streamlined small hat (the wide part is not at the neckline, but at the shoulders and elbows). The previous big round hat not only increased the weight, but also was not conducive to keeping warm. Some people call this new sleeping bag "beer barrel", while others call it "cocoon type". Actually, it's just the alienation of the first two sleeping bags. It absorbs the advantages of the first two kinds of sleeping bags and abandons the disadvantages of the first two kinds, which greatly improves the comfort of carrying and using.