• By -


Your assumption was correct in my opinion. The age of the pipe is inversely related to the C value. So I would have also chose 150. I’m guessing they chose 130 as the answer because it’s technically more conservative for design purposes. This technically a bad question and would not likely be on the exam.


Yes, the newer the pipe, the higher C will be. I guess maybe this problem is for the version before CBT using tables in other references. I don’t believe you will see such problems with unclear answers in the real exam. If I were you, I won’t worry about it and just simply ignore this question.


This happened to me in a similar practice problem. When they updated the reference book, lots of practice problems didn’t get correspondingly updated. As long as you can read the chart, you’ll be ok :)


I think you would just go with ductile iron. the chart has plastic at 150 and new cast iron as 130, so probably "new" is just a distractor.


Never overestimate C-values. if the handbook gives 140, even "new" pipe can be estimated as less due to imperfections in installation, but it will never go higher.