known: horizontal galvanized iron pipe -.06m diameter rate - 0.02 m^3/s Pressure

Question

known: horizontal galvanized iron pipe -.06m diameter
rate - 0.02 m^3/s
Pressure drop- 135 kPa/10m pipe
Question: is it new, used with some roughness due to ageing, or really used with much roughness.

I found a Re # to be 423564
Roughness ration /d= .0025
head loss hf = to be 13.789

I figured if I found the Re and the roughness ration I can use the moody table to figure out if flow was turbulent or not but my Re does not seem to fit. Also I didnt take into acct the pressure drop at that point so im sure im missing something
Thankyou

Explanation / Answer

Given:

Q=0.02 m^3/s

D=.06 m

Assumptions:

=1000 kg/m^3 (density of water)

e=0.00015 for galvanized pipe (from chart)

=.001002 N s/m^2 (from chart at 20 C)

Solve:

Area: A=D^2/4

A=(.06 m)^2/4=

Velocity: Q=AV => V=Q/a => V= 0.02 m^3/s / 0.002827 m^2 => V=7.07 m/s

Re=VD/ => Re=(1000 * 7.07 * .06)/(0.001002) => Re= 4.24 * 10^5 (Same as you)

Relative roughness=k/D => .00015/.06=.0025 (Same as you)

From Moody chart, the approximate friction factor for the pipe should be 0.028.

Calculate friction factor to compare:

D'arcy Weisbach equation:

p=(l/D)(*V^2/2)

l=length of pipe

=friction coefficient

=[(135*10^3/10)*0.06*2]/[1000*7.07^2] => =0.032

Conclusion: The pipe has 14% larger friction factor than a new pipe. The pipe could be classified as old.

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