Help with pressure drop/transposing formula to get pipe diameter

Click For Summary
SUMMARY

The discussion focuses on calculating the internal diameter of a pipe using the pressure drop formula. The user provided specific values: a length of 160 meters, a flow rate of 300 liters per second, and a pressure drop of 0.3 Bar. The derived diameter calculation resulted in an internal diameter of approximately 394.98 meters, which the user questioned due to its impracticality. The formula used involves parameters such as pressure ratio and flow rate, indicating a need for clarity on unit consistency in the calculations.

PREREQUISITES
  • Understanding of fluid dynamics principles
  • Familiarity with pressure drop calculations
  • Knowledge of pipe flow equations
  • Experience with unit conversions in engineering
NEXT STEPS
  • Review the Darcy-Weisbach equation for pressure drop in pipes
  • Learn about unit conversions in fluid mechanics
  • Explore the implications of flow rate on pipe diameter
  • Investigate common mistakes in pressure drop calculations
USEFUL FOR

Engineers, fluid mechanics students, and professionals involved in pipeline design and analysis will benefit from this discussion.

mrose94
Messages
1
Reaction score
0
Homework Statement
A compressor delivers 300 s–1 of free air into a pipe at a pressure of
6 bar gauge. Using the pressure drop formula: Pressure drop = 800lQ^2/Rd^5.31. Calculate the minimum diameter of pipe if the pressure drop in a system is
to be limited to 0.3 bar when is delivered through a pipe of equivalent
length 160 m .
Relevant Equations
pressure drop = 800lQ^2/Rd^5.31
Hello.

My attempt at the solution is as follows:

l = 160m
Q= 300 ls-1
R= p2/p1= 6+1.01/1.01 = 6.94 (2dp)
d = Unknown
Pressure drop = 0.3 Bar

0.3 = 800*160*300^2/6.94*d^5.31

0.3 = 1.152x10^10/6.94*d^5.31

0.3 ( 6.94*d^5.31) = 1.152x10^10

6.94*d^5.31 = 1.152x10^10/0.3

d^5.31 = (1.152x10^10/0.3)/6.94

d= 5.31 root (1.152x10^10/0.3)/6.94

d= 394984.81 mm (I think mm is correct?)

d= 394.98 M

I'm struggling to see how this answer can be correct as an internal diameter of a pipe being so large seems ridiculous to me. Any help as to where I've gone wrong would be appreciated. Thank you!
 
Physics news on Phys.org
In the pressure drop formula what are the units of the various parameters supposed to be?
 

Similar threads

  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
3
Views
2K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 6 ·
Replies
6
Views
8K