- #1
Jim4592
- 49
- 0
Hey everyone! I'm trying to determine the losses through a pipe network that consists of 254.5 feet of 0.75 inch diameter copper pipe.
The flow rate is 0.37125 gpm, with a corresponding velocity of 0.26962 fps. The fluid is water at 150 degrees F.
Based off that information, I have a Reynolds Number of 3655.67
To calculate my friction factor I have three equations, which I'm trying to determine which one is appropriate:
1) f = 1.325(ln(0.27(e/D)+5.74(1/Re)^0.9))-2
this produces a friction factor of 0.22143, with a total head loss (including minor losses from elbows, etc.) of 1.039 feet
2) f = (1.28*g*K1)/(C1.85*D0.02*(Re*v)0.15)
using this I get a friction factor of 0.0413, total head loss = 0.2 feet
3) 1/f0.5 = -0.86*ln((e/3.7D)+(2.51/(Re*f0.5)))
using #3 it produced an f of 0.9979, total head loss = 4.61 feet
As you can see these produce vastly different results, I'm just confused as to how to go about calculating the friction factor for this pipe system with my given Reynolds number. For instance equation 1 says it is valid for 8,000,000 > Re > 5000 so I don't believe that is an appropriate head loss.
Equation 2 doesn't really specify any applicable ranges or Reynolds numbers, just that it incorporates the Hazen-Williams coefficient.
Equation 3 says it was an empirical equation to represent the Moody diagram for Transition Zone. Since my Re is greater than 2000 but less than 5, that's where I think it falls.
Any advice is appreciated!
Thank-You,
-Jim
The flow rate is 0.37125 gpm, with a corresponding velocity of 0.26962 fps. The fluid is water at 150 degrees F.
Based off that information, I have a Reynolds Number of 3655.67
To calculate my friction factor I have three equations, which I'm trying to determine which one is appropriate:
1) f = 1.325(ln(0.27(e/D)+5.74(1/Re)^0.9))-2
this produces a friction factor of 0.22143, with a total head loss (including minor losses from elbows, etc.) of 1.039 feet
2) f = (1.28*g*K1)/(C1.85*D0.02*(Re*v)0.15)
using this I get a friction factor of 0.0413, total head loss = 0.2 feet
3) 1/f0.5 = -0.86*ln((e/3.7D)+(2.51/(Re*f0.5)))
using #3 it produced an f of 0.9979, total head loss = 4.61 feet
As you can see these produce vastly different results, I'm just confused as to how to go about calculating the friction factor for this pipe system with my given Reynolds number. For instance equation 1 says it is valid for 8,000,000 > Re > 5000 so I don't believe that is an appropriate head loss.
Equation 2 doesn't really specify any applicable ranges or Reynolds numbers, just that it incorporates the Hazen-Williams coefficient.
Equation 3 says it was an empirical equation to represent the Moody diagram for Transition Zone. Since my Re is greater than 2000 but less than 5, that's where I think it falls.
Any advice is appreciated!
Thank-You,
-Jim