Balancing of a Water and Air System (PDF

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16 using the density correction. • With figure 3.2 Verify that velocity measurements are acceptable. A traverse plane is suitable for flow measurements if more than 75% of the velocity pressure readings are greater than 1/10 of the maximum velocity measurement and are not negative. • Show all traverses in the final report which will show duct size, static pressure at the traverse, velocity pressure and corresponding velocity, duct area, and the airflow. If the traverse is taken in other than standard conditions, show barometric pressure and temperature. Show density corrections for each traverse. Round Duct Traverse For field traverses any duct that are greater than 10" (250 mm) diameter, use the standard Pitot tube. Two holes located 90" apart in the same plane are required to make a Pitot tube traverse of a round duct. The Pitot tube must be marked so that velocity pressure readings (10 for each hole) can be taken at centers of equal concentric areas. Pitot tube locations for traversing round ducts with 20 readings are as follows in Figure 3.1. 16
17 For traverses taken in round duct equal to or less than 10" (250 mm) in diameter, a l/8" (3 mm) diameter Pitot tube shall be used. The 1/8" (3 mm) diameter Pitot tube must be marked so that 12 velocity pressures (six for each hole) can be taken at the center of equal concentric areas. Pitot tube locations for traversing the round duct with 12 readings are given in Figure 3.2: Square or Rectangular Duct Traverse Performing a Pitot tube traverse of a square or rectangular duct, the number and spacing of the holes in the duct and the markings on the Pitot tube are determined using the following method: The minimum number of readings taken in a square or rectangle duct is 4. This would be for a duct with height and width 4" (100 m) or less. The number of readings for each side will be based on Figure 3.3. 17
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: 15 15 Example 3: Find the nearest s
Page 19 and 20: 19 Flat Oval Duct Traverses For fie
Page 21 and 22: 21 Balancing Devices Volume Dampers
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
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67 For every outside temperature ot
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69 4. Identify the riser with the h
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71 2. Turn the pump off 3. Close th
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73 Net positive suction head availa
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75 All automatic control valves mus
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77 77
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79 4. Read and record the actual pu
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81 13. Record the coils design and
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83 Air Control Air is always presen
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85 • allow draining of all or par
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87 Valves have linear throttling ch
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89 to all the terminals down the li
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91 Pump Circuits Primary-Secondary
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93 • Evaporator: • the design a
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95 95
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97 Condenser • the design and act
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99 • Each reading of liquid tempe
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101 • Design and actual entering
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103 differs from the average by mor
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105 • Orifice plate • Turbine m
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107 BTUH = GPM X 60 X 8.337 X ∆T
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109 Lam = lbs. of air per minute th
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111 When dry bulb temperature measu
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113 GPM = FPM X Gallons per foot FP
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