# Connecting a pipe line to and existing distribution system

• MikEngineer
In summary, the flow rate at the end of the 1500' run can be found by using the energy equation and iterating to find the friction factor. The pressure at the end of the pipe can then be calculated, as well as the pressure at the two TEEs. The flow rate can then be found using the cross sectional area and velocity at the TEEs.
MikEngineer

## Homework Statement

I am connecting a 4" diameter PVC pipe to an existing distribution system. there will be a single check valve (K=2), eight 90 elbows (K=.9) and ten gate valves (K=0.2). I am trying to find the flow rate at the end of a 1500' run and what pressure I would see if I were tie this into a house. Max Pressure in system in 120 psi. z1 = 0 and z2 = 45 feet
y = 62.4 lbf/ft^3 specific gravity; u = 1.41 x 10^-5 ft^2/s (kinematic viscosity).

## Homework Equations

Energy Equation: gamma = y and alpha = a;
P1/y + a1(V1^2/2g) + z1 + hp = P2/y + a2(V2^2/2g) + z2 + ht + hL

hL= sum(f(L/D)(V^2/2g)+sum(K(V^2/2g))

## The Attempt at a Solution

P1/y + a1(V1^2/2g) + z1 + hp = P2/y + a2(V2^2/2g) + z2 + ht + hL

Assume a1=a2; turbulent flow
v1 = v2; incompressible flow, same diameter pipe and point 2 is taken just before water exits open valve at the end of 1500'
hp = ht = 0; no pump or turbine. Therefore
p2 = 0; open to atm.

P1/y + z1 = z2 + hL => hL = P1/y + z1 - z2 = (120 psi * 144 in^2/ft^2)/(62.4 lb/ft^3) + 0 - 45 feet = 232 feet = hL

hL= sum(f(L/D)(V^2/2g)+sum(K(V^2/2g)) = (V^2/2g)(f*L/D + sum[K])

solve for V in terms of f => V = (2g*hL)/(f*L/D + sum[K]) > [14940.8 / (4500f + 11.2)]^(1/2) = 4.05

now we need to iterate using the Moody Diagram or the Swaame-Jain equation.

let f = 0.2 => V = 4.05 => Re# = (4.05*(4/12))/1.41x10^-5 = 1.35x10^6 = 9.5 x 10^5

Iteration eventually yields f = 0.0142 and V = 14.1 ft/s

So my question is this, am I correct in my assumption that V1 = V2 = 14.1 ft/s when the end of the 1500 extension is left opened to the atmosphere?

I can get my flow rate by Q = AV = Pi/4 (4/12)^2 * 14.1 = 1.23 ft^3/s => 9.2 gps => 552.2 gpm.

So, assuming I am correct up this point, How do I now figure out what pressure could be delivered to two houses, if the end of the pipe is closed with a valve and two TEE's are placed one at 1200 feet and the other at 1280 feet.
l TEE to one house
It would look something like this -----------------l-------l-----GV closed
l TEE to house 2

#### Attachments

• Design Calculations for Water Line97-2003.xls
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Last edited:
for calculations. The pressure at the end of the pipe is calculated by:P2 = P1 + (V1^2 - V2^2)/(2g) where P1 is the pressure at the inlet, V1 is the velocity at the inlet, V2 is the velocity at the outlet, and g is the acceleration due to gravity. The pressure at the two TEE's is then calculated by P1 = P2 + (V2^2 - V3^2)/(2g) where V3 is the velocity at the TEEs. The flow rate can then be calculated from Q = AV, where A is the cross sectional area of the pipe, and V is the velocity at the TEEs.

## 1. How do I determine the size and type of pipe needed to connect to an existing distribution system?

The size and type of pipe needed will depend on the flow rate and pressure of the existing distribution system, as well as the intended use of the new pipeline. It is important to consult with a hydraulic engineer or use a pipe sizing calculator to determine the appropriate pipe size and material.

## 2. What is the best way to connect to an existing distribution system?

The best way to connect to an existing distribution system will vary depending on the specifics of the system and the location of the connection. In general, it is recommended to use a flanged connection or a mechanical joint for a secure and leak-proof connection.

## 3. Are there any regulations or permits required for connecting a pipe line to an existing distribution system?

Yes, there may be regulations and permits required for connecting a pipe line to an existing distribution system, depending on the location and type of system. It is important to check with local authorities and obtain any necessary permits before beginning the connection process.

## 4. How can I ensure the new pipeline does not disrupt the flow of the existing distribution system?

Proper planning and design are key to ensuring the new pipeline does not disrupt the flow of the existing distribution system. This may include conducting a hydraulic analysis, using check valves or flow control devices, and coordinating with the operators of the existing system.

## 5. What are the potential risks or challenges of connecting a pipe line to an existing distribution system?

Some potential risks or challenges of connecting a pipe line to an existing distribution system include damage to the existing infrastructure, disruption of service, and potential environmental impacts. It is important to carefully plan and execute the connection to minimize these risks and address any challenges that may arise.

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