1. Calculation formula<br>① Σ q = 0 is the sum of flow to any node, which should be equal to the sum of flow away from the node (including node flow).<br>② ⊿ H = 0, that is to say, in each closed loop, the water loss of pipe section with water flow as clockwise direction is positive, while that in counter clockwise direction is negative, and the sum of positive values should be equal to negative values. In the actual calculation center, the closure error can be controlled according to the following requirements:<br>Small ring: ⊿ h ≤ 0.5m; large ring: (from the beginning to the end of the pipe network): ⊿ h ≤ 1.0m.<br>2. Pipe network adjustment steps<br>① Draw the pipe network adjustment operation chart, mark the length of each calculation center pipe section and the ground elevation of each node.<br>② Calculate the central node flow.<br>③ Plan the direction of flow and make preliminary distribution of flow.<br>④ According to the initially allocated flow, the pipe diameter of each pipe section of the pipe network shall be selected according to the economic flow rate (the flow rate of the pipe network near the water plant shall be slightly higher than the economic flow rate or the upper limit, and the flow rate at the end of the pipe network shall be less than the economic flow rate or the lower limit).<br>⑤ Calculate the water shut-off loss of each pipe section, i.e. H = IL<br>⑥ Calculate the closure difference ⊿ h of each ring in the center; if the closure difference ⊿ h does not meet the requirements, adjust it with the correction flow (generally adjust the large ring first and then the small ring) until the closure difference of each ring reaches the above requirements.<br>The corrected flow rate can generally be estimated. However, in the closed loop, if the diameter and length of each pipe section have little difference, the corrected flow rate (⊿ Q and ⊿ h direction are opposite) can also be approximately obtained by the following formula<br>
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