Document yrG1kxov9gp5QaGn6NpNk0jLD

434 CHAPTER 19 1950 Guide Fio. 3. Equivalent Length of Fittings (Concluded) GROUP 7. REGISTERS (INCLUDING LOSSES IN STACKHEAD AND VELOCITY PRESSURE). DEFLECTION ANCLE. 25 EQ. FT. PL.REG.& BOX ONLY Table 4A. Equivalent Length fob Registers Deflection Angle A 0* Ifi* 22* 10* Baseboard, High or Low Sidewall Eq. Ft. Registers 35 40 45 00 Floor Registers with Box only 25 45* 115 Far 2-way deflection registers, add the vertical and horizontal deflection angles together and multiply 0.7. Select closest angle A In Table 4A. 6 for buildings having a heat loss between 120,000 and 350,000 Btu per hr or Table 6 for buildings having a heat loss greater than 350,000 Btu per hr, Select shortest actual length and read downward in nearest column in Tables 5 or 6 until lower heavy diago nal line is reached, but do not cross line. Hun horizontally to first column of table and note bonnet temperature. Also select longest actual length and read downward in nearest column in Tables 5 or 6, until upper heavy diagonal line is just crossed. Run horizontally to left to obtain value for bonnet temperature in first column. Se lect as the design bonnet temperature any value between these two limits. 5. Determination of air volume to be delivered through each register and the respective register air temperatures. Using Tables 5 or 6 and the design bonnet temperature selected, find the values of cfm per 1000 Btu for each duct length. 6. Selection of register sizes and pressure losses to produce necessary throw, for the air volumes handled. Use Tables 7 or 8 to obtain required free area and pressure loss of register. 7. Design of duct system. A. Warm air branches. a. Use Table 9 to select maximum bonnet pressure usually required for the trunk carrying the maximum volume of air (cfm). If the maximum bonnet pressure is not high enough to accommodate the pressure loss through the registers, use a higher bonnet pressure.. If the register pres sure is critically large, it may be necessary to reduce it by either using . two registers in place of one, or using smaller deflection angles. b. Obtain actual duct loss by subtracting register pressure loss from maxi mum bonnet pressure. c. Obtain the pressure drop in each duct per 100 ft by use of Table 10. d. Determine duct size by means of air friction chart (such as Fig. 1, Chapter 31), volume (cfm), and pressure drop per 100 ft of duct. B. Return air branches. a. Select a low value of actual duct loss obtained from step b under item A for the suction loss of return duct system/. b. Proceed in sizing return air branches by the same method described for the warm air branches. C. Trunk duels for warm air and return air sides of system. a. Add air volumes of branches to be handled by each trunk duct. b. The friction loss per 100 ft of trunk duct is determined by taking the smaller of the two values for friction loss for the two ducts meeting at the junction. c. Determine trunk duct size by using an air-friction chart, volume (cfm), and pressure drop per 100 ft of trunk duct. T a b l e 5. Se l e c t io n o f B o n n e t T e m p e r a t u r e , R e g is t e r T e m p e r a t u r e a n d R e g is t e r D e l iv e r y (CFM )1 {For Buildings Having a Heat Loss between IBOfiOO and S50,000 B T U /H r.) Register Delivery Volume in CFM per 1000.B T U per H r. L in e a r D istance rs o u B onnet to E boistbe, in F eet 98 97 96 95 94 93 29.6 30.5 31.5 32.3 33.3 34.6 126 123 121 119 117 115 113 111 110 108 107 105 104 103 102 101 16.9 17.6 18.1 18.7 19.3 20.0 20.7 21.6 22.1 23.1 23.6 .24.8 25.4 26.0 26.6 27.3 116 114 112 111 109 108 106 105 103 102 101 100 99. 98 97 96 95 94 93 92 91 90 90 19.6 20.3 21.1 21.6 22.5 23.1 24.2 24.8 26.0 26.6 27.3 28.0 28.8 29.6 30.5 31.5 32.3 33.3 34.6 35.9 37.3 38.6 38.6 101 100 99 98 97 96 95 94 93 92 91 90 90 89 89 88 88 87 27,3 28.0 '28.8 29.6 30.5 31.5 32.3 33.3 34.6 35.9 37.3 38.6 38.8 39.9 39.9 41.3 41.3 42.7 : 230 | 240 0TC I ooz Mechanical Warm-Air Systems . 00 CO oto o 190 | 170 | | 001 1 150 1 |no 120 | 130 1 s a S O co iso<0 ' s. co o ow<Co4 o 107 108 104 23.6 .24.2 25.4 s 8 o ? B 6* no ob^ ss; 128 16.4 118 19.0 140 130 120 137 14.6 134 131 129 126 124 122 120 118 116 114 112 16.1 15.7 16.2 16.9 17.3 17.9 18:4 19.0 19.6 20.3 21.1 109 107 106 105 103 102 101 100 22.5 23.6 24.2 24.8 26.0 26.6 27.3 28.0 98 97 29.6 30.5 147 12.9 143 140 137 134 131 129 127 124 122 120 118 116 114 112 n o 109 107 106 13.5 14.0 14.6 15.1 15.7 10.2 .16.6 17.3 17.9 18.6 18.4 19.6 20.3 21.1 22.1 22.5 23.6 24.2 103 102 101 100 26.0 26.6 27.3 28.0 160 166 11.8 152 149 145 142 139 136 133 130 128 126 123 121 119 117 115 113 112 n o 108 107 106 104 103 12.3 12.7 13.2 13.7 14.2 14.8 15.3 15.9 16.4 .16.9 17.6 18.1 18.7 19.3 20.0 20.7 21:1 22.1 23.1 23.6 24.2 25.4 26.0 901 on 811 801 191 991 091 170 157 163 150 146 143 140 137 134 131 128 126 124 122 120 118 116 114 112 n o 11.7 12.2 12.6 13.1 13.6 14.0 14.6 15.1 15.7 16.4 16.9 17.3 17.9 18.4 19.0 19.6 20.3 21.1 22.1 107 106 23.6 24.2 OI 881 rzz on 9' ZZ 601 8 '^Z SOI 180 135 131 128 126 124 122 120 118 116 115 113 111 n o 14.9 16.7 16.4 16.9 17.3 17.9 18.4 19.0 19.6 20.0 20.7 21.6 22.1 190 435 135 132 129 127 125 122 120 118 116 114 14.9 15.5 16.2 16.6 17.2 17.9 18.4 19.0 19.6 20.3 156 153 149 145 142 139 136 133 130 128 126 124 121 119 117 115 113 112 11.8 12.2 12.7 13.2 13.7 14.2 14.7 15.3 15.9 16.4 16.9 17.3 18.1 18.7 19.3 20.0 20.7 21.1 171 167 163 158 154 161 147 144 140 10.4 10.7 11.1 11.6 12.1 12.4 12.9 13.4 _14.0 166 161 157 153 150 *146 143 140 10.8 11.3 11.7 12.2 12.6 13.1 13.5 14.0 CO W w-i *s. f-'II 601 091 991 U i| 51 174 169 10,1 10.6 cr--o 0) w O) 0)00 o* co 00 WO) owo O) S'*. caoo) WO) woo It 1*0 176 10.0 200