Balancing of a Water and Air System (PDF

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20 .06 ” .08 ” .10 ” .12 ” .14 ” CFM of Ducts at a Friction Loss in inches of water Per 100 feet of duct at 29.29” Duct sizes in inches 5” 6” 7” 8” 9” 10” 12” 14” 16” 18” 20” 22” 52 85 123 175 240 320 505 775 1100 1500 1940 2450 60 97 143 210 270 365 600 900 1390 1725 2290 2950 68 109 162 240 315 420 690 1000 1460 1975 2610 3150 75 120 178 255 345 485 750 1110 1600 2200 2900 3600 84 130 195 270 387 510 830 1200 1750 2400 3180 3950 CFM of Ducts at different Velocity Velocity in Feet per minutes at 29.92” Ducts 5” 6” 7” 8” 9” 10” 12” 14” 16” 18” 20” 22” FPM 600 83 120 160 208 265 330 475 650 850 1040 1300 1600 800 110 160 210 280 350 440 625 850 1150 1600 1750 2100 1000 138 195 265 345 440 550 790 1090 1400 1780 2190 2420 If an installation has an inadequate straight length of ductwork or no ductwork to allow a pitottube traverse, the procedure from Sauer and Howell (1990) can be followed: a vane anemometer reads air velocities at multiple points across the face of a coil to determine a loss coefficient. 20
21 Balancing Devices Volume Dampers Balancing dampers are a primary component in duct systems, and their importance should not be ignored. Balancing dampers are used to control the volume of airflow in the system by creating a resistance to flow. Balancing dampers can produce unnecessary resistance and noise problems, and will not control the air as intended if improperly selected, located, installed, or adjusted. The relationship between the position of a damper and its percentage of airflow with respect to the airflow through a fully open damper is termed its “flow characteristic.” Opposed-blade dampers are generally recommended for large ducts because they provide better control of the airflow, and therefore have better flow characteristics than parallel blade dampers. The actual effect of closing a damper can only be determined from field measurements. Proper location of balancing dampers not only permits efficient air distribution but also equalizes the pressure drops in the different airflow paths within the system (Figure 6.1). Manually operated opposed-blade or single-blade, quadrant-type volume dampers must be installed in every zone duct of a multi-zone system and each branch duct takeoff to control the amount of air entering the branch. Manual dampers should be provided in each branch takeoff to control the airflow to grilles and diffusers. Single-blade or opposed-blade volume dampers located immediately behind diffusers 21
Page 1 and 2: Balancing of a water and air system
Page 3 and 4: 3 8 TBA (Testing, Balancing and Adj
Page 5 and 6: 5 Air Balancing Multiple Hood syste
Page 7 and 8: 7 87 Series Loop 88 One pipe main 9
Page 9 and 10: 9 Testing and Balancing HVAC A syst
Page 11 and 12: 11 13. Filter frame properly instal
Page 13 and 14: 13 13. Measure and record all requi
Page 15 and 16: 15 15 Example 3: Find the nearest s
Page 17 and 18: 17 For traverses taken in round duc
Page 19: 19 Flat Oval Duct Traverses For fie
Page 23 and 24: 23 Turning Vanes Turning vanes (Fig
Page 25 and 26: 25 Balancing the VAV System The gen
Page 27 and 28: 27 maximum out-side air damper for
Page 29 and 30: 29 determines how much energy is in
Page 31 and 32: 31 the water removing capacity of a
Page 33 and 34: 33 Table 8A Dry Bulb on left, Wet B
Page 35 and 36: 35 60 58 56 54 52 50 48 46 44 42 40
Page 37 and 38: 37 Foot³ per 1lb Altitude 0 Feet A
Page 39 and 40: 39 Table 9 C Air Density at 29.29
Page 41 and 42: 41 41 Wet-Bulb (F) .0 .1 .2 .3 .4 .
Page 43 and 44: 43 Table 11A Enthalpy at saturation
Page 45 and 46: 45 Table 11 C Enthalpy at saturatio
Page 47 and 48: 47 Wet bulb temperature____________
Page 49 and 50: 49 and replacement should be shut o
Page 51 and 52: 51 duct may be great; the balancing
Page 53 and 54: 53 Design below the 250°F limit (A
Page 55 and 56: 55 Differential Pressure Gauges The
Page 57 and 58: 57 Venturi The venturi is a device
Page 59 and 60: 59 Pressure Total pressure Velocity
Page 61 and 62: 61 Table 1 shows that if the coil i
Page 63 and 64: 63 adjustment of these devices is n
Page 65 and 66: 65 Grouting Motor and lubrication N
Page 67 and 68: 67 For every outside temperature ot
Page 69 and 70: 69 4. Identify the riser with the h
Page 71 and 72:
71 2. Turn the pump off 3. Close th
Page 73 and 74:
73 Net positive suction head availa
Page 75 and 76:
75 All automatic control valves mus
Page 77 and 78:
77 77
Page 79 and 80:
79 4. Read and record the actual pu
Page 81 and 82:
81 13. Record the coils design and
Page 83 and 84:
83 Air Control Air is always presen
Page 85 and 86:
85 • allow draining of all or par
Page 87 and 88:
87 Valves have linear throttling ch
Page 89 and 90:
89 to all the terminals down the li
Page 91 and 92:
91 Pump Circuits Primary-Secondary
Page 93 and 94:
93 • Evaporator: • the design a
Page 95 and 96:
95 95
Page 97 and 98:
97 Condenser • the design and act
Page 99 and 100:
99 • Each reading of liquid tempe
Page 101 and 102:
101 • Design and actual entering
Page 103 and 104:
103 differs from the average by mor
Page 105 and 106:
105 • Orifice plate • Turbine m
Page 107 and 108:
107 BTUH = GPM X 60 X 8.337 X ∆T
Page 109 and 110:
109 Lam = lbs. of air per minute th
Page 111 and 112:
111 When dry bulb temperature measu
Page 113 and 114:
113 GPM = FPM X Gallons per foot FP
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