| The purpose of this project was (1) to evaluate the effect of filling material variables, bag construction variables, and the use of auxiliary products on the insulation provided by sleeping bag systems and (2) to develop regression equations for estimating the insulation value of sleeping bag systems from bag, clothing, and pad variables. Prototype bags were constructed with material and construction variables controlled at the same level except for the independent variable to be studied. In addition, five thicknesses of pads, three levels of clothing insulation, and five levels of bag insulation were evaluated in all possible combinations to determine their effects on bag system insulation. The effects of other auxiliary products such as pillows, liners, and hats were studied also. The thermal insulation value of a sleeping bag system was measured according to ASTM F 1720-96, Standard Test Method for Measuring the Thermal Insulation of Sleeping Bags Using a Heated Manikin. The weight, thickness, and packing volume of the bags were measured, and the insulation per unit weight and insulation per unit thickness were calculated.; The amount of down, the fill power of down, baffle height, and fill ratio had an effect on bag insulation, as did the type and amount of synthetic fiberfill. Bag construction (layered, shingle) and design features such as draft tubes, neck collars, and bag shape affected bag insulation also. The use of auxiliary products such as pads, clothing, pillows, bag liners, etc. increased the insulation of the bag system---particularly the use of pads.; Regression equations were developed for predicting the insulation of a sleeping bag system (with or without clothing) that explained 99% of the variance in insulation with an accuracy of +/-0.3 clo. The equations used clothing insulation, pad thickness, and either bag insulation or bag thickness and weight as input variables. Manufacturers can use the regression equations to predict the insulation of their sleeping bags when used with different types of clothing and/or pad thicknesses for the purpose of determining temperature ratings with heat loss models. |
