Problem # 11 - PE Exam.com Exam No. 1

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DanHalen

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Problem 11 states:

Water is pumped through 200 ft of 1 in diameter pipe at a velocity of 2 ft/sec. The pipe has one angle valve, a 90o elbow, and a 45o elbow, and C = 140. The total loss in the pipe system is most nearly:

A) 0.38 ft

B) 6.09 ft

C) 4.68 ft

D) 5.00 ft

I worked this problem using a slightly different method and got close to the same answer. The solution used K value for the fittings and I used equivalent length. Would the equivalent length be acceptable for solving this problem? The K value gives 4.66 ft and equivalent length comes out to 4.72 ft.

 
DH,

Either way is fine for this problem.

You can use either the Hazen-Williams formula to solve for hf, substituting L with Lequiv. (hf ~ 4.7')

Or use the Hazen-Williams formula to solve for hf using regular L and add the minor friction losses, hminor. (hf + hm => ~4.3 + ~0.4 = ~4.7')

The answers may differ slightly, as you pointed out, but you should always get close using either method.

 
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