Register to reply

Calculating water pressure

by rick326
Tags: pressure, water
Share this thread:
Oct26-04, 08:27 AM
P: 1
Given only the rate of flow in gpm and the inside diameter of a hose in inches, is it possible to calculate the pressure of water leaving the hose?
I have no experience or training in this area but it seems to me that more information would be required. Any help will be greatly appreciated.
Phys.Org News Partner Physics news on
Detecting neutrinos, physicists look into the heart of the Sun
Measurement at Big Bang conditions confirms lithium problem
Researchers study gallium to design adjustable electronic components
Oct26-04, 08:44 AM
P: 25
it's been a while, but i believe that Bernoulli's equation could help. Check that one out
Chi Meson
Oct26-04, 08:55 AM
Sci Advisor
HW Helper
Chi Meson's Avatar
P: 1,772
Without getting into very advanced fluid dynamics, it is assumed that the water pressure, after the water has left the hose, is same as atmospheric pressure.

If you are referring to the pressure of the water against a surface (as the water splashes on a surface like your hand, after it leaves the hose) then the "pressure" would be the force of the water/cross-sectional-area of the water stream (assumed to be the area of the hose?) P=F/A

From the volume flow rate (gal/min) you can calculate the "mass-flow rate" (mass/sec), and assuming all the water is stopped, the mass flow rate times the change in velocity will produce the force.
Ft = m[delta]v , so F=(m/t) x [delta]v

So, yes, the pressure of this stream of water against a surface can be calculated from the information given.

Jan21-09, 09:33 AM
P: 2
Calculating water pressure

I am trying to calculate the force exerted on a body during high pressure water blasting. The numbers are 36,000psi pump pressure, 5gpm flow rate. lbs of force back pressure is the number I'm looking for. HELP!
Jan21-09, 04:36 PM
P: 22,294
You need the velocity, then you use Bernoulli's equation to find the pressure. What is the area of the nozzle?
Jan21-09, 04:47 PM
P: 2
There are two nozzles. Both are 1/8" in diameter.

Register to reply

Related Discussions
Calculating the pressure of a fluid Classical Physics 1
Water depth pressure against air pressure Classical Physics 1
Calculating pressure Chemistry 17
Calculating pressure Introductory Physics Homework 0
Calculating solar pressure General Physics 1