Friction losses: flexible tubing vs copper pipe

[austin]

I'm replacing my old ½" copper water pipes throughout the house (after installing a water softener). The surge tank is set at 60 psi. What is the best solution for maximizing the water pressure at the faucet? ½" or ¾" tubing? Flexible tubing or copper pipe?

[LazyPup]

Perhaps the reason no one has responded sooner is because there really is no easy answer to your question.

You stated that you have 60psi at the surge tank however it must be understood that 60psi is the "Static Head Pressure" which is the total pressure in the system when there is no flow and all is at rest. The moment any faucet is opened and flow begins the entire system will immediately drop to "Dynamic Head Pressure" or what is more commonly known as "Working Pressure". In essence the working pressure at any fixture is the Static Head Pressure minus Vertical Static Head losses and pipe Friction losses.

Vertical Static Head loss is a result of the physical weight of the water in a vertical line and is computed by a constant value of 0.434psi per foot of vertical rise.

Friction Head loss however is not constant. The faster the velocity of flow in a line, the greater the Friction Head loss. By example, a 1/2" type L copper pipe with a flow rate of 1gpm has a friction head loss of 0.010psi/ft of pipe however if we increase the flow to 5gpm the friction head loss is now 0.161psi/ft.

In addition to pressure losses the codes also require that we must size the pipes to keep the velocity of flow under 8ft/sec in copper pipe or 12ft/sec in plastic pipe to prevent pipe wall erosion.

If you will post a list of all the fixtures in your house that are connected to the water distribution system I will be glad to help you work out the details. It would also help if you could post a simple layout drawing showing the location of all the fixtures and the point where your water enters the structure.