7/31/2019 Friction Factor is Calculated

1/2

7/31/2019 Friction Factor is Calculated

2/2

A = log[(e/D)/3.7 (5.02/Re)log((e/D)/3.7 + 13/Re)]

Comments

After my discussion with Art Montemayor and Katmar, I would dare putting the following comments for

member perusal.

1. The friction factor 'f' is Darcy's friction factor(thanks to katmar for pointing out)

2. The comparison of accuracies of these equations is done based upon the presumption that

Colebrook's equation is perfect and flawless.

3. Serghides opines that Zigrang equation and his own equation have the higher accuracies (and this is

tested by Art Montemayor, Katmar and myself)

4. Away from the critical region, the inaccuracy of any of the above equations is insignificant (as

observed by Katmar). I easily accepted this observation due to two facts. The first one is that, the easily

available pipes have diameters in steps(i.e if our flowrate requires a pipe just bigger in size than a 3"

pipe, our option is 4") . Second one is that, we engineers generally require generous FOS for future

expansion and other kind of things.

5. Member Katmar developed a brilliant expression for friction factor by modifying Chruchill's equation,

which is in perfect agreement with Serghides and Zigrang as far as accuracies are concerned.

6. Within the critical region, where 2100