Problem: A T-connection receives 4GPM of water from a 3-quarter inch schedule 40 steel pipe and a 3-feet per second of water from an inch and a quarter sche...
Given: 4GPM of water from a 3-quarter inch schedule 40 steel pipe and a 3-feet per second of water from an inch and a quarte...
Approach: Water exits into an inch and a half schedule 40 steel pipe.
Calc: The velocity is 3 feet per second and then the outlet is an inch and a half and the water's flowing out and we want to know the...
Result: We also have to go into the steel pipe friction tables and get the actual diameters because these are all nominal diameters and it is going to affe...
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Student questions asked in live office hours about this problem
OH 120 · May 11, 2026
Q: For HVAC-Fluids-7, why was velocity calculated by converting GPM to feet per second using Q = VA instead of reading it directly from the steel pipe friction table (which shows 2.41 ft/s for 3/4" pipe at 4 GPM)?
A: Both methods are valid and produce the same result with only minor differences. The steel pipe friction table is faster since it avoids manually calculating the pipe's cross-sectional area from the inside diameter, but solving Q = VA directly using the inside diameter is equally acceptable.