Maximum Water Flow Through Piping

How long are pipes?

Based on your pipe roughness and end line pressure,using pressure drop of 3ft/100ft and velocity of 10 ft/second, using Q=V.A for each pipe and adding all Q using flow(GPM) vs (pressure drop) chart for each 3" and 6" pipe, you'll get your total gallon per minute, then multiplying it by hours and total hours/day requirement you'll get total water/day if possible apply some diversity factor.

Good luck

You do not really give enough information to answer this question, but we can get an estimate by making a few reasonable(?) assumptions (welcome to fluid mechanics!). First, note that it is not pressure but gradients in pressure that drive fluid flow.

To find the change in flow velocity that results from a given pressure gradient, we need to compare the flow at the outlet of your pipe to the flow somewhere upstream of the outlet where the properties are known. If we assume that we can choose some upstream point where the pressure is at the "supply pressure" of 63 PSI, then we also need to know the flow velocity at that point -- for an estimate, assume that it is small compared to the outlet velocity.

At the outlet, the pressure is atmospheric. If we neglect the effect of viscosity (to get an upper limit), then the outlet velocity can be easily calculated from Bernoulli's Equation -- in this case, V = sqrt( 2*(P_i - P_o)/density ); P_i is 63 PSI, P_o is atmospheric pressure, and "density" is the density of water in the appropriate units. To convert velocity to volume flowrate (volume per unit time), multiply by the cross-sectional area of the pipe -- A = pi*R^2. To convert volume flowrate to mass flowrate, just mutiply volume flowrate by the density of water.

Calculate the volume or mass flowrate for each of your pipes and add them up -- this should be an upper limit on the total flowrate. Multiply by 24 hours to get your daily output. (Watch your units!)

Note that in reality, the effect of viscosity should not be ignored in this situation and the length of the pipe between the upstream point and the outlet needs to be known to get a more exact answer.

How large is the supply header?

What is the downstream pressure? Are they open ended to atmosphere?

What style of valve is inline with each pipe, what is the cV of the valve?

Also remember that if there are bends,tees or any other deviation from a straight line you will also have to take into account these will add to your losses.

What type of pipe do you have? Different roughness coeffiecients also have an effect.

Like another message said, it would be useful to know what the gradient of your slope is.

Need to know how long are the pipes, what fittings are installed (if significant compared with pipe lengths), and what is pressure at the outlets - open to atmosphere (0 barg) or what?

Unless lengths are considerable, 63 psi ΔP gives high velocity compared with usual design figures.

The flow in each pipe should be calculated separately. The nett static head (static - delivery) will be balanced out by losses.

The pressure at an open ended pipe is zero.

The flow will diminish in all the pipes as the supply level drops with longer pipes showing the greatest effect.

The pipe suppliers should be contacted for the formula , roughness used etc.

Pipe friction curves should however be sufficient for the purpose.

If the pipes are connected as ring mains the specific flow in each pipe can be determined by iteration.

Need to know what the supply source is. All of the responses have dealt with the obvious pipe info - flow and gradients, but unless you know what the prime mover is capable of you can not infer any of these outcomes. So what is the pumping the water. It will have flow/pressure characteristic curve which defines what it is capable of under various system dynamics. If your from head developed from the "fall" of water say from a dam or elevated tank then this would mean a different approach. Hope this is of some help.

I Ass-u-me-ed again because of insufficient information and responding to other responses.

the "pump' curve pressure-flow must be taken into account. but friction losses will eventually determine the flow in each pipe.

Again assumed that there is one prime mover.

Please supply more detail.

What is the use of these pipes for?

then we can ask for data and assumpsions

"is nice be in games with others"

Because the statement says "I have a facility"..... why not just open all the lines 100% and measure what comes out?

Theory is fine on paper but you may have badly corroded pipes if they are old. Or damage to them which you cannot see. Or your 63PSI pressure may not in actual fact be 63PSI cos pumps deteriorate with time.

This is all assuming that a helpful school kid hasn't shoved his homework in the ends of the pipe cos he's pissed off doing calculations.

As others have noted, you need to confirm what flow rate the supply source can handle first as opposed to what your lines are capable of. The diameter of distribution lines is normally large in comparison to the actual required design flow. This is done in order to keep velocity and friction losses to acceptable levels and pumping costs down in pumped systems.

Example: You might have only an 8" supply line feeding all of your other lines. If you open all 8 of your lines to atmosphere, the limiting factor would be the 8" supply line, because you can't get more than the source can supply. If on the other hand your supply line was a 20", the flow through the smaller distribution lines can calculated .

But you must always know the dynamics of your source. If the delivery supply pressure varies with flow, as is commonly the case, it has to be included in the calculations. And your source most probably has a pressure reducing valve or pump regulator somewhere even if it is unknown to you. These have very specific velocity limitations to prevent damage.

Also as others have noted, it's all much easier if you start from the volume and pressure you need at the point of use and work backwards. The assumption is that your required actual volume is within normal design limits. Doing otherwise introduces far too many factors that cannot be calculated with any certainty in an older existing system, under extreme velocities. It becomes only an exercise with as many solutions as people solving it.

The "rules of thumb" recommend that around 7 feet per second is the usually accepted maximum velocity for water distribution lines. That's a good and practicable limit for long lines and as a starting point. It's not to be taken as law.