Problem: What is the friction loss per 100 feet for 800 gpm of 80 degree water flowing through an 8-inch nominal schedule 40 steel pipe?
Given: 100 feet for 800 gpm of 80 degree water flowing through an 8-inch nominal schedule 40 steel pipe? So in the last prob...
Approach: So in the last problem, we were given a surface roughness and we were able to look up the head loss per 100 feet Directly from ...
Key formula: equation is if you go in the reference handbook and search Darcy It'll come up right away
Calc: It's 0.93 times 10 to the negative 5 and that has units of feet squared per second So all the units cancel and the Reynolds num...
Result: That's probably a two or three percent error So if you feel like you're between answers that's something that you may want to Revisit but for two o...
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Student questions asked in live office hours about this problem
OH 47: HVAC: Fluids-11
Q: Can we use the steel pipe friction tables for this problem instead of the Darcy equation, and is there a reason the solution uses Darcy?
A: There's no reason you can't use the steel pipe friction tables—they're actually faster and I'd recommend them for steel pipe problems. Expect some deviation between methods, but since you're computing just one term in Bernoulli, the absolute difference is usually small and tolerable. Take the results in context: consider the absolute difference, not just the relative error.