Problem: 30 gpm of 120 degree water flows through a nominal inch and a half schedule 40 scale pipe.
Given: 30 gpm of 120 degree water flows through a nominal inch and a half schedule 40 scale pipe; 1.61 inch diameter; 30 gpm...
Approach: You'll get used to doing this and jump down to inch and a half.
Key formula: formula for Reynolds number, which you can look up in the reference handbook, but I'm just going to give it to you ri...
Calc: So let's do that for an inch and a half schedule 40 pipe.
Calc: That actually has a 1.61 inch diameter.
Result: Which is answer to choice C.
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Student questions asked in live office hours about this problem
OH 39: HVAC: Fluids-4
Q: When a problem specifies schedule 40 pipe, should we use that smaller diameter instead of the standard weight pipe diameter from the pipe table?
A: Schedule 40 and standard weight pipe are essentially the same thing for most diameters relevant to the exam. I verified this by cross-referencing multiple sources, and for 1.5" pipe, schedule 40 gives an ID of 1.61", which matches the reference handbook—so use schedule 40 when specified, and treat it as your standard weight assumption.