How do I calculate the flow rate in a 3-inch ID pipe tapped from a 6-inch pipe with a flow rate of 140m3/h?

 How do I calculate the flow rate in a 3-inch ID pipe tapped from a 6-inch pipe with a flow rate of 140m3/h?

Solution

If we assume that the flow enters the pipe and exits unimpeded through both the 6″ pipe and the 3″ tap:

• The volumetric flow into the system must equal the volumetric flow out of it.
• The cross sectional area of the 3″ tap is 25% of that of the 6″ pipe, so the volumetric flow through the 3″ pipe will be 25% of the outward flow through the 6″ pipe.
• The total flow through both outbound pipes is 140m3/h.
• The outbound flows are: 28m3/h through the 3″ tap, and 112m3/h through the 6″ pipe.