The first recommendation is to be clear about the use that will give to the SAC and then choose one that suits the type of use without sin buy a sack with little insulation and can go cold during rest or with too much isolation and have heat. Another aspect to consider is that sacks do not create heat, just prevent the loss of body heat.
There are two types of stuffing in sleeping bags, fiber or synthetic fabrics and the Quill. The main difference in a very summary manner would be to synthetics facilitate maintenance and pen provides a high quality insulation.
Temperature of use
Temperatures of use we collect are based in 13537 standard which is currently the only directive which guarantees a methodology and a standard. The definitions of each temperature contained in the regulations are comfort, limit and extreme.
It is the temperature that a sleeper will sleep within the SAC no sweat. It is measured with the zipper open, arms out and open hood. The measurement is performed with a man of 25 years, 1.73 m tall and 70 kg.
Temperature in which a wife of 25 years, a weight of 60 kg and 1.60 m in height can sleep in the fetal position without going cold. Or a middle man sleep in relaxed position. It is the temperature to have in mind at the time of purchase.
At this temperature the bag protects from hypothermia. Allowing maximum 6 hours of sleep in the fetal position a standard woman with cool feeling.
Aspects that influence the thermal sensation
Each person is a world. This phrase is also extrapolated to the chill. There are people more frioleras and warmer. Below are explained aspects influencing the cold sensation of each person as well as outdoor conditions affecting also.
The loss of heat from within SAC is due to driving or by direct contact with the ground or other various means. For example, radiation is loss through direct contact of heat, this effect is increasing with the wind. More weight sleeper sack is more compressed and losses are greater when there is more contact with the ground. The use of mattress cushioning the weight of the sleeper is convenient to reduce this loss. Is another means of temperature loss evaporation. Sweat has a body to regulate temperature and is effective if the humidity is capable out of the sack, if not, this is moistened and cause discomfort for the sleeper. It also will sack to lose their thermal characteristics being more problematic this aspect in feather bags since they absorb more moisture than synthetic.
Generated by our body temperature also depends on physiological factors. The loss of body heat depends on the metabolism of each person and plays a significant part of their body weight. As a reference you can take a 50 kg person generates 60 watts of heat. While a 110 kg person generates 100 watt.
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With more fat people have a greater capacity for insulation. People with a greater muscle mass also generate more heat. Thin people tend to generate less heat.
Women tend to be colder than men, being the difference of about 5 ° C for the temperature in 13537 standard comfort. This difference tends to be due to muscle mass and body fat.
The trend with age is to generate fewer calories. Muscle mass with age also tends to decrease.
People who are prepared and usually leave are likely to feel less cold. In addition if a person is very tired generates less heat than that is more rested. The known is very important because a person who know will know how to bundle up and with what to feel less cold.
Before sleep power consumption
The amount of energy generated during sleep depends on the activities carried out during the day. For example a person who has made a quiet hike and has eaten hot food will be in a better position than a climber who has made a great effort.
Types of construction
It is the most typical cutting nowadays, being wider at the top and narrower at the feet. This design is more efficient in retaining heat since the amount of air in the interior of the bag is smaller. It also weighs less and takes up less space than straight sacks because it requires less material.
They are the classic type of bag. They have a zipper that allows full opening of the bag and can use this as a blanket. This bag is suitable for the more restless people, because that provides greater freedom of movement for the legs. On the other hand heat retention is worse since more air is inside and also weighs and takes up more space when it is collected.
Adapted Mummy type
These bags are more flared at the height of the chest and knees, providing greater mobility. These bags provide maximum comfort and an optimal heat retention.
Types of internal construction
If the filling of a sleeping bag is not structured, accumulate in a few spots and other cold spots would be created. Why sacks are made with different compartments. The partitions may normally be in the form of H, the simplest segmentation. SEPTA are parallel with H-shape which prevents the filling to move. Another type of separation is trapezoidal, whose shape prevents displacement of the filling and also prevents cold spots unfilled. As the walls are not straight between the outside and the inside of the bag ensures that there will always be a layer of padding between the inside and the outside. Bags with synthetic insulation can also be constructed in layers. If a sack is built in layers, two or more, each layer is superimposed to maximizing the thermal efficiency. An example would be a bag with three layers. Layers would run thus:
- A first inner layer that reflects body heat avoiding the loss.
- A second layer of fill with fibers that keeps the air between their cavities.
- Another layer that ensures the retention of heat of the entire structure.
Its main function is to prevent heat loss. There are several types of collars depending on usage. Extreme collars are like a vest and reduce heat loss to a minimum. In lighter sacks do not require them since the bags are not designed to withstand extreme temperatures, although some have a necklace consisting of a padded layer that surrounds the neck providing support and reduce heat loss. The closure which have collars are normally push-button, for easy opening and closing.
Compartment designed for a pillow size approximately, allowing that during sleep the pillow out of the bag. In addition, it provides a head of outside insulation.
Adjustment of the hood parafrio rubber
The size of the hood can be easily adjusted using a gum adjustment according to the user and the outside temperature.
Feet have more space to move them, since it increases the habitable volume at the bottom of the bag. In addition, due to the special design filling is less compressed which also produces a thermal improvement.
Compartment for feet
Compartment specially created for the feet. This adaptation makes that there is less air through a compartment, so it gets an improvement in thermal as well as keeping feet dry from the outside. Due to the least amount of air, improving thermal and together with the use of socks, the improvement is acute.
Pocket inside network
Interior pockets that allow small and important elements by hand.