Balancing of a Water and Air System (PDF

More documents

Recommendations

Info

88 Check Valves Check valves allow water to flow in one direction and stops its flow in the other direction. There are two types of check valves: swing and spring loaded. Check valves should be used at the discharge of the pump. With swing check valves, when the system is off the weight of the gate and gravity closes the valve. The valve is opened when the system is turned on, in addition, pressure from the fluid flowing in the proper direction causes the gate to swing open. Spring-loaded check valves have springs that keep the valve closed. Water pressure from the proper direction against the spring opens the valve. Combination Valves Combination valves (Figure 11.21) are sometimes referred to as a multipurpose or tripleduty valves. They are a combination of a check valve, a calibrated balancing valve, and a shutoff valve. They are made in a straight or angle pattern. Combination valves act as a check valve, preventing back flow when the pump is off, and can be closed for tight shutoff, or can be partially closed for balancing. These valves have pressure taps for connecting flow gauges and for reading pressure drop across the valve. A calibration chart is provided with the valve for conversion of pressure drop to gpm. The valves also have memory stops. Series loop The series loop is a simple and inexpensive piping arrangement generally limited to residential and small commercial building applications. In series loops (Figure 11.32), supply water is pumped through each terminal in series and then returned to the boiler. Since all the water is circulated in succession through each terminal, there are several disadvantages to the series loop arrangement. First, making repairs at any one terminal requires shutting the whole system down. Second, it is not possible to provide capacity controls on individual terminals, because valuing down one terminal would reduce flow 88
89 to all the terminals down the line. Instead, space heating must be controlled by dampening the airflow. These disadvantages can be partially remedied by designing the piping with two or more circuits, and installing balancing valves in each circuit (Figure 11.33). This type of arrangement is called a split series loop. The series loop circuit length and pipe size are also very important in the design because they directly influence the water flow rate, temperature, and pressure drop. For instance, as the heating supply water flows through the terminals, its temperature drops continuously as it gives up heat in each terminal. If there are too many terminals in series, the water temperature in the last terminal may be too cool to be effective. One Pipe Main One-pipe mains are used in houses and small commercial and industrial heating applications where individual space control is needed. This arrangement uses a singleloop main but differs from series loop arrangements in that each terminal is connected by a supply and return branch pipe to the main (Figure 11.34). Because the terminal has a 89
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 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
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: 87 Valves have linear throttling ch
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
show all

Balancing of a Water and Air System (PDF

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?