Thread: What actual water pressure will I be getting?

Originally Posted by blackgang

That is how some range finder rifle scopes used to work.
But what you need to know is elevation from Tank to waterlevel.
so if you had a GPS you could take a fix at the verticle line under the tank.
Then take a fix at the pump setting, and that will give you a distance on a horizontal line directly under your tank, then with a level take a shot with a P-Shooter[eye level] from pump to top of tank, now you have A and B so triangulate it to find C. which will be a line 90* off horizontal under the tank. OK, I am not to good at explaining as I was a worker not a teacher.

hi blackgang

as someone mentioned here gps is accurate to 5m. if it's +-5m for 1 reading, we could potentially have an error of 20m for 2 readings up and downhill.

if the above scenario is correct, then a ruler with its inherent errors might not be too far off.

plus the cost of acquistion of a ruler is much lower than that of a gps. and i think i have a ruler lying around somewhere

What ever blows your dress up, makes me no difference.
You started out at 100m elevation over pond, then said maybe 40 or 50, so it is damn hard to really tell, like computers are wonderful tools but Garbage in = Garbage out.
The only thing any of us could do was take your info and then make suggestions as to what we would do if it were us doing the job, and we did the best we could.
So thank you for time, it has been a pleasure.

hi blackgang

i am very grateful for your help and the information provided

and realised that my previous post could have come across as insensitive and ungrateful

i never meant it that way.

you were right in your admonishment and i apologise unreservedly for my insensitivity

No problems here, this is TD remember, libeled to see anything here.

Very true WS, and I was using the pump recommended by Norton and it was a 2x2 so 2 inch was what I would have thought that he would use.
But not used to dealing with people that have no ideas about what is going on leaves me somewhat at a disadvantage.

Originally Posted by Whiteshiva

Originally Posted by wanna

Originally Posted by blackgang

Originally Posted by DrAndy

That distance is the real distance along the ground slope, not the apparent horizontal distance you would get with a GPS. So it can be measured directly and the height calculated using the angle

No it is not the length of the pipe in this instance, but the elevation of the tank in relation to the elevation of the water surface in the pond.
on a horizintal distance as short as that, internal viscosity and drag loss is not going to make much difference, as water can be pushed along fairly easy, but lifting it to 40 or 100 meters is what counts and that is figured from horizontal to tank elevations, it makes no difference to the pump if it has to raise the water directly overhead or 100 yards away, it is still how high it will push it for general purposes.
it takes 10.5 kPa of pressure to push water up every one meter of elevation and each one pound of pressure is equal to 6.9 kPa, some pumps are rated in kPa.
So off the top of my head it will take at least 75 psig to raise the water 50 meters.

although i dont understand the full rationale behind it, the above argument upon 1st reading sounds very logical and convincing

hence i am saving it for future reference

Apart from the reference to viscosity and drag (?) loss. The viscosity is water will not change (significantly) but the pipe/fitting losses are real, and are directly related to the pipe diameter (and internal smoothness of the pipe - not something you can easily do anything about anyway). If your pipe is big enough, the pipe losses will become rather small compared to elevation effects, but if you have an undersized system, you will find it very hard to reach your desired flowrate.

As an example - a 2" pipe flowing at 10 m3/hr will have a pressure drop of approx. 41 kPa/100m.

Using a 1" pipe, and the number becomes 1415 kPa/100m, i.e. a 35-fold increase in pressure drop!

yes another useful piece of info. use at least 2" piping. would pe pipes be better than pvc in reducing fitting losses?

Originally Posted by blackgang

Very true WS, and I was using the pump recommended by Norton and it was a 2x2 so 2 inch was what I would have thought that he would use.
But not used to dealing with people that have no ideas about what is going on leaves me somewhat at a disadvantage.

i dont think it's me this time....or is it?

Friction loss in plumbing: Friction Loss in Plumbing

Gravity Flow Rates: Gravity flow rates and examples - Koiphen.com

GPM/GPH Flow based on PVC pipe size: GPM/GPH Flow based on PVC Pipe Size, ie, How much water can flow through Sch 40 Pvc Pipe Size 1/2" 3/4" 1" 1.5" 2" 2.5" 3" 4" 6"

Hope this can help out some.

Originally Posted by wanna

i dont think it's me this time....or is it?

I think it's you.