-548 THE MECHANICS OF VENTILATION. 



-Assume a sectional area of 6 square feet ijY each inlet, and 

 222 



=37=numLer of inlets. 



6 

 -Assume again that velocity in outlets is 6 feet per second. 

 888 



=148 square feet=area of outlets. 



6 

 Also let area of each outlet be 6 square feet, same as inlets 

 U8 



z=25 number of outlets. 



6 

 The discussion has taken no account of the increase in volume due to 

 the increase of temperature. Were such account taken the dimensions of 

 outlets would be somewhat increased. 



The number of changes per hour under the above conditions maybe de- 

 termined by two methods, either b}^ dividing the suppl}- per hour for each 

 person by the volume for each person, thus, 

 2000 



=13.9 



144 

 or b}^ dividing the total suppi}' per hour by the total available volume of 



the hall, thus. 



3200000 



=13.9 



230500 

 giving the same result in either case. 



The discussion has also proceeded upon the supposition of no loss by 

 'Conduction and radiation. We will now consider the modifications of the 

 •above calculations due to these sources of loss. 



The hall is warmed by steam, direct radiation. Number of sets of ra- 

 -diators 18, each having an area of 60 sciuare feet. Total radiating surface, 



therefore. 



60 xl8=1080 square feet. 



Amount of space heated bv one square foot of surface equals 

 230500 



zzz213.4 cubic feet, 



1080 

 wliich is certainly ample for the coldest weather likely to be experienced 

 ,Siere. 



To find loss by conduction through walls and windows, we will assume 

 Inside temperature at a mean between temperature of entering air and tem- 

 perature to which it is raised by heat from persons and lights, or say at 

 71°. Outside temperature is taken at 32°. The outside exiDOSures are three 

 la Qumber, two sides and one end. We will consider the loss of heat only 

 ii'om. the three outside exposures, neglecting the protected end, ceiling and 

 'So or. 



Area of the three exposed sides exclusive of windows^6306 square feet. 

 Area of windows=::1096 square feet. 



