Firefigting nozzle pressure and reaction

Click For Summary
SUMMARY

The discussion focuses on calculating nozzle reaction force for a ladder pipe with a 2-inch tip at 80 psi nozzle pressure. The correct reaction force is established as 502.4 pounds, derived from the formula NR = 1.57 D²NP, where D is the diameter in inches and NP is the nozzle pressure in psi. This contrasts with the calculation using Pi*r², which yields only 251.33 pounds. The discrepancy arises from the different methodologies used to calculate the reaction force.

PREREQUISITES
  • Understanding of Newton's third law of motion
  • Familiarity with firefighting equipment specifications
  • Basic knowledge of pressure calculations in firefighting
  • Ability to perform area calculations using geometric formulas
NEXT STEPS
  • Research the formula NR = 1.57 D²NP for nozzle reaction force calculations
  • Study the principles of fluid dynamics as they apply to firefighting
  • Explore the impact of nozzle design on reaction forces
  • Learn about different firefighting nozzle types and their specifications
USEFUL FOR

Firefighters, fire safety engineers, and anyone involved in firefighting operations who needs to understand nozzle reaction forces and their calculations.

Chris314
Messages
1
Reaction score
0
A ladder pipe with a 2" tip at 80 psi nozzle pressure will have approximately ____ pounds of nozzle reaction.
Now I've been out of college and out of practice with my math and physics skills for quite a while. With studying my firefighting materials for operations, a lot of the statements by these books do not add up. The answer given to the above question is 502.4 pounds of reaction force. Newton's third law of motion states to every action; equal and opposite reaction. Pi*r^2 to find the area of the nozzle would give me 3.1416 square inches of surface area and when multiplied by 80 pounds per square inch I arrive at 251.33 pounds of reaction force from the nozzle. So why would the book answer be approximately twice my answer?
 
Physics news on Phys.org
Hmm... according to this site the reaction force is given by NR = 1.57 D²NP.
So in your case it would be NR = 1.57 (4)(80) which equals 502.4 lbs of reaction force.

I'm not sure why the formula is different from Pi x r2.
 

Similar threads

Graduate Optimal Size of Rocket Engine Nozzle for Vacuum Performance
  • · Replies 26 ·
Replies
26
Views
4K
Undergrad Find Best Water Nozzle Type & Pressure for Longest Distance
  • · Replies 32 ·
2
Replies
32
Views
12K
Undergrad Nozzle Reaction Forces: Explaining the Resultant Force
  • · Replies 51 ·
2
Replies
51
Views
38K
Graduate Predicting how far an object will fly
  • · Replies 1 ·
Replies
1
Views
1K
Undergrad Calculating pressure with U.S. customary units
  • · Replies 10 ·
Replies
10
Views
3K
Undergrad Understanding the thrust generated by a typical jet engine
  • · Replies 2 ·
Replies
2
Views
3K
Force of pressurized water exiting a hose or pipe?
  • · Replies 20 ·
Replies
20
Views
11K
Undergrad Optimal Copper Pipe Size for Misting System
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Changes in volume change total force?
  • · Replies 11 ·
Replies
11
Views
3K
Undergrad Pressing hydraulic pressure questions
  • · Replies 8 ·
Replies
8
Views
6K