The heat balance of sleeping bags

Science has long infiltrated all areas of human activity and, of course, in the sector of development and production of equipment for extreme conditions. In this article we are talking about such an integral and important pieces of gear like a sleeping bag: about the temperature conditions to which it is designed, the applicable standards.

science has long infiltrated all areas of human activity and, of course, in the sector of development and production of equipment for extreme conditions. in this article we will focus on such an integral and important pieces of gear like a sleeping bag: about the temperature conditions to which it is designed, the applicable standards.

bask company uses all modern scientific achievements in the field of thermal security, but everyone who is planning to test their capabilities in extreme conditions, whether climbing, skiing or mountain trekking, needs to imagine an accurate picture of what determines its comfort, how to achieve the most comfort, what you need to focus. so...

heat balance

man it was warm, it is necessary that the following conditions: the amount of heat that he generates, should equal the amount of lost heat or exceed it. the process and the amount of heat generated in the human body depends primarily on the metabolism or metabolism.

heat transfer due to the following features:
  • thermal conductivity surfaces, especially the earth's surface
  • air circulation and heat loss during breathing
  • the evaporation of moisture from the skin surface
  • infrared heat radiation
the main heat loss is due to the thermal conductivity of the surface and air circulation, including breathing. based on the foregoing, understand the formula of thermal balance is quite simple:

heat balance: playback of thermal energy = thermal energy losses by heat conduction, circulation, evaporation and radiation.



physiological factor in the heat balance

the main task of the sleeping bag is to keep warm. the main source of heat is the man. now let us consider what affects the efficiency of a sleeping bag.

thermal energy exchange processes

a sleeping person produces from 75 to 100 watts of heat. for a man of average build, this means that per square meter of the surface of his body falls from 47 to 55 watts of heat energy (this ratio is expressed in W/m2). metabolic processes are very complex, and their intensity, and hence the heat generated, depend on size and age and sex. for example, a young, well-nourished man produces more heat than a man older, and a lot more women. at the same time, feeling cold more inherent to novice tourists than experienced travelers. as well as people who frequently work outdoors, are less susceptible to hypothermia (hypothermia) than office workers. the General trend is that upon reaching 25 years, people usually dense physique more cold-resistant than lean.

complexion

obese people are seen to have reduced metabolism. more precisely, they absorb more than they produce. in people of normal physique metabolism is balanced, they absorb as much produce. in field conditions, it often happens that a person gets fewer calories than usual. this is most evident in polar, polar and Alpine expeditions. in such circumstances, the body uses its own resources to restore metabolic processes. accordingly, more people will be quicker to recover heat and energy balance, rather than more lean.

Paul

women are considered to be more heat-loving than men. according to the latest standard en13537, minimum temperature for women to 5C higher than that of men.

age

metabolism changes with age. older men produce less heat than younger people. young people have an increased heat exchange, so they comfort temperature may well be 5C lower than the adult. thus children, especially infants, do not have this property sufficiently. their metabolism unbalanced and gradually slow down with age, so it is very difficult for them to determine the average temperature.

environment

almost all the research in the field of heat exchange are produced in the people connected with extreme conditions, be it the military, the guides, climbers. as a rule, are men aged 18 to 40 years, unlike the majority of the population, most of the day conducting outdoors: such lifestyles, of course, increases resistance to cold. this should be considered.

experience

experience and knowledge of equipment contributed to a better understanding of their own features of heat exchange. because freshmen, the first time faced with the problem of choosing a sleeping bag, as a rule, will feel discomfort during sleep.

let's consider the basic concepts adopted for determining the temperature of comfort or extreme:

comfort temperature – the temperature range in which a person can sleep without feeling cold all night. at this range, there are upper and lower limit. the upper temperature limit of comfort – the highest temperature at which you can sleep in a sleeping bag without sweating (usually it is calculated during testing in the sleeping bag unzipped and folded with the hood). the lower temperature limit of comfort – the lowest temperature that provides 8 hours of continuous sleep.

temperature extremes – the lowest temperature at which the sleeping bag protects a person from hypothermia (hypothermia). typically, this temperature should provide 6 hours of uncomfortable sleep, but without reducing body temperature to dangerous indicators. these data are governed at present by national and international standards for sleeping bags, including the European en13537.

temperature en13537 standard

en13537 has been developed by the European group of producers of goods outdoor. its main task is to confirm or refute information provided by the manufacturers of sleeping bags on the temperatures. the standard was adopted in 2002. from 1 January 2005 entered into force the new act, including on the procedure of testing and publication of results. in other words, the standard provides for testing of all claimed to sell sleeping bags in the laboratory. all sleeping bags on sale after 1 January 2005 are required to comply with the en13537 standard. after receiving the test results meet the requirements, the manufacturer has the right to place their products CE marked.

the standard is used in the following European countries: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom (T.E. England). unfortunately, Russia is not in this list. this is due primarily to the lack of corresponding Federal standards. of Russian companies producing sleeping bags, while only bask can afford the certification according to the European standard en13537.

What's new in the standard en13537?

the main difference from the previous standard - the presence of a temperature scale for the description of the product provided by the testing laboratory.


let's examine this example. the average woman can sleep comfortably in this sleeping bag when the air temperature is between +22C to +4C, and the average man - at a temperature of +22C to -1C. in the product catalog, respectively, will be specified maximum limit of comfort, in this case 1C. this sleeping bag should keep enough heat to prevent hypothermia (hypothermia) at temperatures up to -18C. but at temperatures from -1C to-18C there is already a health risk.

how should I understand the temperature scale?

based on the ambient temperature, in which there is a person in a sleeping bag. during testing the dummy used in full human growth with connected temperature sensors. the temperature of the dummy corresponds to the average temperature of the human body. in the laboratory, where tests are conducted, a certain temperature, at this time from the sensors on the dummy readings are taken of the energy losses required to maintain a stable temperature at the installation point of the sensor. based on these data, is compiled temperature scale, which the manufacturer may indicate in the specifications of the sleeping bag. it is important that it is now possible to compare the temperature ratings of sleeping bags from different manufacturers on a single scale.
  • t max – maximum ambient temperature in which a person in a sleeping bag feels comfortable
  • comfort – lower limit of comfort for the average woman
  • limit – lower limit of comfort for an average man
  • – the risk of hypothermia


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