• Support PF! Buy your school textbooks, materials and every day products Here!

Help with pressure drop/transposing formula to get pipe diameter

  • #1
1
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!
 

Answers and Replies

  • #2
20,230
4,264
In the pressure drop formula what are the units of the various parameters supposed to be?
 

Related Threads on Help with pressure drop/transposing formula to get pipe diameter

Replies
3
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
2
Views
513
  • Last Post
Replies
2
Views
1K
Replies
2
Views
21K
Replies
10
Views
2K
Replies
5
Views
6K
  • Last Post
Replies
0
Views
2K
Top