Document qaJybeM97RGjyQrEOqe6jRbRG

American Society of Heating and Ventilating Engineers Guide, 1928 Table 4. Internal Conductivities of Building Materials and Insulations1--Continued B. insulations--(Continued) Material Description Density (Lb. per Cu. Ft.) Temp, op Sample (Dec. . Faur.) Internal Conduc- (C OR Cu) authority 1-1 7.0 90 0.27 Bureau of Standards binder. 9.7 0.32 Willard, Lichty & Harding binder. Kapok between 2.0 90 0.25 Bureau of Standards burlap or paper. 13.6 90 0.32 13.0 90 0.31 14.0 70 0.32 Peebles, Armour Institute ; i Hairiasul10........... j Hairinsul10-. -......| 75 per cent hair___ } 25 per cent jute...... 50 per cent hair___ j 50 per cent jute...... 6.3 6.! 90 90 0.27 0.26 Bureau of Standards Bureau of Standards . Hair felt10.__ Felted Cattle Hair 13.0 90 .0.26 Bureau of Standards Hair feltTM................ Felted Cattle Hair 11.0 90 0.26 Bureau of Standards Insulex or Pyrocell Cellular Gyspum__ 30.0 90 1.00 Bureau of Standards Insulex or Pyrocell Cellular Gypsum__ 30.0 75 0.92 Peebles, Armour Institute Insulex or Pyrocell Cellular Gypsum__ 24.0 90 0.77 Bureau of Standards Insulex or Pyrocell Cellular Gypsum_. 24.0 - 75 0.737 Peebles, Armour Institute Insulex or Pyrocell Cellular Gypsum 18.0 90 0.59 ' Bureau of Standards Insulex or Pyrocell Cellular Gypsum. 18.0 75 0.566 Peebles, Armour Institute Insulex or Pyrocell Cellular Gypsum. 12.0 90 0.44 Bureau of Standards Insulex or Pyrocell Cellular Gypsum. . 12.0 75 0.400 Peebles, Armour Institute 16.9 90 0.34 Bureau of Standards lation made from wood pulp. Insultte...................... Board form insu- 16.5 70 0.34 Peebles, Armour Institute lation made from wood pulp. Keystone Hair10.;__ 11.0 75 0.25 4.9 90 0.28 Bureau of Standards tween paper. Tith 14.3 90 0.40 Bureau of Standards and straw pulp with binder. T-ith Rock wool, flax 14.5 75 0.38 Peebles, Armour Institute and straw pulp with binder. 18.0 75 0.33 Peebles, Armour Institute lation made from exploded wood fiber. Maftex_______ Board form of in- 36.1 81 0.337 Peebles, Armour Institute sulation made from roots of licorice. Regranulated Cork_ About % in. par- 8.1 90 0.31 Bureau of Standards tides. Rock Wool10 ....... Fibrous material, 10.0 90 0.27 Bureau of Standards made from rock. Also made in sheet form, felted and confined with netting. Ten Test- __ __ . Board form insu- 20.0 75' 0.46 Peebles. Armour Institute lation made from wood pulp. Thermofelt10. ,, _ Jute and asbestos 10.0 90 0/37 Bureau of Standards fibers, felted. Thermofelt10.... ....... Hair and asbestos 7.8 90 0.28 Bureau of Standards fibers, felted. - Thermofill_________ Powdered Gyp- 34.0 90 0.60 Bureau of Standards sum. Thermofill___ ______ Powdered Gyp- 26.0 90 0.52 Bureau of Standards sum. Thermofill.________ _ Powdered Gyp- 24.0 : 75 0.475 Peebles, Armour Institute Thermofill____ ____ Powdered Gyp- 18.0 75 0.34 Peebles, Armour Institute sum. 14 Chapter I--Calculating the Heat Losses from Buildings Table 5. Factors to be Used in Determining Values of Outside Surface Coefficients (K2) under Moving Air Conditions In each case, the moving air factor is based on still air coefficient (AT,) for same material. For conditions where wind velocity is not known use the factor (3) or take K: as 3Kx for same material. Wind Velocity in Miles per Hour 5 10 15 20 Brickwork 2.38 3.20 3.76 4.22 Multipliers of Ki* Wood 2.19 2.71 2.95 3.02 Average 2.28 2.96 3.36** 3.62 10 20 Above 20 Additional Values--Smooth Surface ..... 2.20 ....... 2.60 ^....... 3.00 ..... ....... ........ Taken from Engineering Experiment Station Bulletin No. 102, of the University of Illinois. Addi tional values from Engineering Experiment Station, Pennsylvania State College, reported by Professor Wood. Tests at Pennsylvania State College indicate character of surface, rough or smooth, more important than material of surface. This is usually taken as 3 even. Heat Transmission Data Heat transmission coefficients of many common types of building construction are given in Tables 6 to 12, inclusive, each construction being identified by a serial number. For example, in Table 6-A, the coefficient of transmission (Z7) of a 13-in. brick wall, furring strips, and % in. of gypsum plaster on metal lath, is 0.185, and the number assigned to a wall of this construction is 3-b. The coefficients in these tables were determined by computations similar to those shown in Fig. 3, using the value of C (or Cu`) indicated. The authorities for the conductivities used for computing these coefficients are given in Table 4. As in the case of the examples in Fig. 3, the average value of 1.34 given in Table 3 for K, was used for all surfaces in still air. The value of for outside wall and roof surfaces was taken as 3 X K,, or 4-02, corresponding to a wind velocity of approximately 15 miles per hour. A value of C = 8.3 for stone concrete (1- 2- 4 mix) was used for com puting the values of U for all constructions involving this material. It is quite probable that the true conductivity of stone concrete approaches the value of 6.3 obtained from tests conducted by Professor Peebles of Armour. Institute, when the concrete is thoroughly dry and well cured. If, for a certain concrete construction, it appears that the value of 6.3 is more nearly correct, the engineer may at his discretion compute the value of U on the basis of this figure. This of course is true of other constructions. The Research Laboratory of the American Society of Heating and Ventilating Engineers has developed an apparatus known as the Nicholls heat meter for the determination of the heat loss through any type of construction, and by means of which the value of U for any construction may be ascertained by actual test. The Nicholls heat meter consists essentially of a plate of bakelite, 2 ft. square and ]/g in. thick, This plate is equipped with thermocouples which are so constructed as to the two surfaces of the plate, produces a difference in electrical potential between the thermocouples. The plate is calibrated so that this difference in potential, when measured, can be converted into terms of heat trans- lCu is the conductivity (or conductance) for construction or thickness stated. 15 x