5.2 Pump Capacity
The flow unit capacity of the pump is indicated on Page 14, Table 2, as a function of installed altitude. When the
number of flow units carried in the tube.
See Figure 15. Readings for length and flow when plotted on the graph must fall on OK side to avoid excessive vacuum losses.
FIGURE 15: Vacuum Loss Curve for 4" Shared
Tailpipe
Table 2: Pump Capacity
Installed Altitude | Maximum Flow Units | ||||
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Feet Above | Meters Above | ||||
Sea Level | Sea Level | Series | Series | ||
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0' - 2000' | 0 m - 609 m | 66 | 112 | 224 | |
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2001' - 3000' | 610 m - 914 m | 63 | 105 | 215 | |
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3001' - 4000' | 915 m - 1219 m | 60 | 100 | 206 | |
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4001' - 5000' | 1220 m - 1524 m | 57 | 95 | 197 | |
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5001' - 6000' | 1525 m - 1828 m | 54 | 90 | 188 | |
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6001' - 7000' | 1829 m - 2134 m | 51 | 84 | 180 | |
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7001' - 8000' | 2135 m - 2438 m | 48 | 80 | 170 | |
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8001' - 9000' | 2439 m - 2743 m | 45 | 75 | 161 | |
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There are a number of design requirements which, if not met, will reduce the vacuum obtainable and thereby the effective flow capacity of the pump. These include:
•Minimum Length of Tailpipe - If less than the minimum length of tailpipe is provided per radiant branch, there will be insufficient cooling of the com- bustion gases and improper operation of the pump.
•Line Loss Check for Tailpipe is applicable to sections of tailpipe which are common to two or more radiant branches (i.e. shared lengths). See Page 14, Figure 15.
•Excessive back pressure on discharge line of pump can be caused by partial blockage or too much flow for length. See Section 5.3.1
•More than maximum number of burners or flow units per radiant branch. See Page 14, Table 2.
•Excessive number of elbow or tee fittings which increases vacuum loss.
5.3 Tailpipe Flow
Excessive flow loading in a single section of tailpipe can cause low vacuum and lower effective pump capacity. For the pump to develop the proper vacuum, the length of tailpipe must not be excessive for the
NOTE: For 6" (15 m) tailpipe, length is limited to a maximum of 100’ (30 m). See Page 16, Section 6.3 for more details.
Lengths shown include allowance for 1 elbow every 50' (15 m); deduct 15% of length for each additional elbow used per 50' (15 m) length.
5.3.1 Pump Exhaust Length Requirements
The tube length on the exhaust side of the pump is considered excessive if not within the following condi- tions:
Table 3: Pump Exhaust Requirements
Pump Series | Exhaust Tube Length | Exhaust Tube Diameter |
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Up to 25' (7.6 m) | 4" 3 Elbows | |
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Up to 50' (15 m) | 5" 3 Elbows | |
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Up to 10' (3 m) | 4" 0 Elbows | |
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Up to 25' (7.6 m) | 5" 3 Elbows | |
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Up to 50' (15 m) | 6" 3 Elbows | |
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Up to 10' (3 m) | 6" 1 Elbows | |
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Up to 25' (7.6 m) | 7" 3 Elbows | |
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Up to 50' (15 m) | 8" 3 Elbows | |
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