I have a static water pressure of 60PSI, and a 3/4" main line into the house.?

Question

the faucet outsie is connected with a 1/2" pipe, and the GPM is only around 5-6 GPM. That is what I put the pressure guage on and I know it is restricted due to the small pipe. If I tap into the 3/4" main line to run a sprinkler system what should the GPM be? my guess is that it will be around 8-10GPM. Does anyone know how much the smaller pipe reduces the GPM?

Answer 1

Keep in mind that the pressure will regulate how much water will flow though your sprinkler not the pipe size. Yes 3/4 inch vs 1/2 will have an effect but most sprinkler systems will have restrictions to water flow. If your are running more than one branch off the main line to numerous sprinklers then yes you have to start off with 3/4 and drop down to 1/2 as you branch off. this will also keep the pressure up on your branch lines.

Answer 2

Seems Like Your Geuss Is Pretty Acurate to Me, It Will Definitely Be At Least 2 GPM More taping into a 3/4" from a 1/2".

But It Actually Depends On Your Sprinkler System (The Lenght Of Sprinker Tubing, It's Witdth And The Roughness Of The Pipe Wall To A Much Smaller Degree).

Water Is Like Electricity, If The electricity Is Going Through A Thinner wire, There Is More Resistance.

So If You Have Smaller Pipes Coming Off The Line Your Tapping Into, The GPM will Obviously Be Reduced Again.

Answer 3

The static pressure is good, however what you need to know is what the flow pressure is.

Here are some flow values for a home. Remember these are averages.

Water Demand

Each fixture in the system represents a certain demand for water. Some examples of approximate water demand in gallons per minute (gpm) of flow, are:

* Drinking fountain - 0.75
* Lavatory faucet - 2.0
* Lavatory faucet, self closing - 2.5
* Sink faucet, WC tank ball cock - 3.0
* Bathtub faucet, shower head, laundry tub faucet - 4.0
* Sill cock, hose bibb, wall hydrant - 5.0
* Flush valve (depending on design) - 3.5
* Shower head - 2.2

Adding up numbers like these to cover all the fixtures in an entire building distribution system would give the total demand for water usage in gpm, if all of the fixtures were operating and flowing at the same time - which of course does not happen. A reasonable estimate of demand is one based on the extent to which various fixtures in the building might actually be used simultaneously.

So given these numbers any flow by tapping off the house supply will reduce the total available capacity.

The difference in the 1/2" and 3/4" at open flow from the same source will be very minimal.

Take a look at the Tables here:
http://www.tpub.com/content/construction/14259/css/14259_48.htm

Hope this helps.

Answer 4

Actually, you will have to put the 3/4" into a "manifold", and from that, you will probably go off into a 1/2" inch pex tubing for your sprinkler system. (make sure that the manifold is below ground level and the sprinkler system, so that you can drain the system in the winter time, and not crack the sprinkler heads with freezing).

Also you should have control valves, (solenoids), and a timer system, so that it will restrict your flow a wee bit too. (Unless you plan on doing this manually, then you will still have the 5-6 gpm which is sufficient enough for any yard, as you wont have them all going at the same time, only different "zones" at various times during the day).

I wish you well..

Jesse

Answer 5

an outside faucet ie a tap.... usually is connected before the pressure reducing valve off the main of the house. (you can have one.) city pressure is higher so youll have more pressure and a little flow.....but most copper and plastic pipes can handle 300 psi these days... if you have taps outside make sure there is no restricter in the tap.... they are set to 2.5 gallons per minute..the new plumbing code.

Answer 6

the faucet him self is reduced to a 3/8

Answer 7

the 3/4" line is 25% larger than the 1/2 line
so you should have 25% more flow...

Answer 8

if you reduce by half, your gpm will also be reduced by half