Regarding the selection of pipe diameter
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Hai Youhao: Our company needs to install a circulation pump with a head of 44 meters and a flow rate of 300 m3/h. What diameter should the outlet pipe have? I also would like to ask how to calculate the flow rate of the fluid in a pipeline. Thank you
The flow velocity of general liquids in the pump outlet pipeline can be estimated at 1.5–2.5 m/s.
10 inches and 250mm is moderate. The flow rate is measured by a flow meter
Diameter of 300, equipped with a circulation water pump of 300 m3/h
Refer to HG/T 20570.6 - 1995 for pipe diameter selection
The range from DN200 to 300 can meet a flow rate of 300 m3/h
The best choice is a pipe diameter of DN250, which is quite appropriate!
The flow velocity at the outlet of the centrifugal pump is 1.5 m/s. d2=300/(3600x0.785x1.5)=0.0708; taking the square root gives d=0.266m. Therefore, a pipe diameter of dn=250mm is sufficient.
There is a problem at the moment: our company has three circulation pumps for 7-degree chilled water, with a flow rate of 400 m3/h each. These pumps are always in operation, and their outlet pipes are connected together via a DN250 pipe. Logically, the flow rate through a DN250 pipe should also be around 400 m3/h. However, the combined flow rate measured in two of the workshops is approximately 800 m3/h. What’s going on? Could it be that the flow meters in those workshops are broken? I hope someone can help explain this. Thank you
The flow rate of a DN250 pipe can be much higher than 400 m3/h; based on the principle of economic flow velocity, it is roughly at that level. The three circulation pumps you mentioned are connected in parallel, right? What is the flow rate of each individual pump?