# split line of 2" copper water line from city

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by novice-man, Aug 4, 2009.

1. ### novice-manNew Member

Joined:
Aug 4, 2009
Like below drawing, city water flows in 2â€ copper pipe with 45psi, and then it splits into another 2â€ line ( (a) line ) and continue to run (b) line.
There is 2â€ Ball Valve in the middle of (A) line.

What happens if the ball valve in (A) line closed half(50%)?
1) (B) line gets any benefit? More pressure? Or more flow?
Or,
2) (B) lineâ€™s water volume and pressure remains the same?

Thanks much,

--Novice-man

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2. ### jimboPlumber

Joined:
Aug 31, 2004
Location:
San Diego, CA
It all depends on flow. If the flow in A was such that the dynamic pressure at the split point was being dropped by flow in the main supply, the reducing the flow to A would cause the dynamic pressure at the split point to be higher, so B would flow more.

4. ### hjModerator & Master PlumberStaff Member

Joined:
Aug 31, 2004
Occupation:
Plumber
Location:
Cave Creek, Arizona
pipe

That is like asking, "How high is up?" Your answer depends on the dynamics of the system, how much water is available, how much is being used at both A & B when the valve is open, if A is using its maximum amount when the valve is open and if more is needed at B, and if the pipe to B is able to carry more volume. And, a ball valve should not be adjusted to anything other than full open or fully closed to avoid destructive turbulence.

5. ### novice-manNew Member

Joined:
Aug 4, 2009
what is "destructive turbulence"?

6. ### MASTERPLUMB777Member

Joined:
Aug 6, 2007
Occupation:
Retired Master Plumber
Location:
Texas
Copper pipe split

You know like in the "GRAND CANYON " !

When you have a ball valve in less then fully open or closed

it disturbs the water steam and causes erosion to the inside the pipes and

fittings ! !

7. ### novice-manNew Member

Joined:
Aug 4, 2009
just erosion?
if 45 degree close, is this mean 50% close, right?

8. ### jadnashuaRetired Defense Industry Engineer xxx

Joined:
Sep 2, 2004
Occupation:
Retired Systems engineer for defense industry.
Location:
New England
A ball valve should be either open or closed...anything in between can cause the pipes to literally wear out from the inside.

9. ### novice-manNew Member

Joined:
Aug 4, 2009
Then, gate valve is OK?

10. ### msgaleMember

Joined:
Sep 28, 2006
Location:
Ohio
no, gate valves also should be all open or all closed

11. ### novice-manNew Member

Joined:
Aug 4, 2009

1) how long can I use copper pipe before it destruct and erode make a hole or leak? ( if I use a ball-valve)

2) what kind of valve can I use to close 50%?

Thanks,

12. ### nhmasterMaster Plumber

Joined:
Jul 30, 2008
Occupation:
Tech. Instructor
Location:
S. Maine
A globe valve. Flow is redirected from a chamber in the lower part of the valve, up and through the seat assembly and finally out the top chamber. That action keeps the flow from constantly wearing against one portion of the valve or pipe.

www.nibco.com

Joined:
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Occupation:
Location:
Chicago, IL
Why do you want to throttle the water supply so badly? A properly designed system you should not have a need to do this.

14. ### hjModerator & Master PlumberStaff Member

Joined:
Aug 31, 2004
Occupation:
Plumber
Location:
Cave Creek, Arizona
valve

quote; just erosion?
if 45 degree close, is this mean 50% close, right?

If I could understand what you are asking, I might be able to answer the question.

15. ### novice-manNew Member

Joined:
Aug 4, 2009

1) ball valve causes only "erosion" issue? how bad it is? and how long can the pipe hold the erosion before corrupt? and how many years can I use the pipe? and how will happens eventually, e.g. hole? or leaking?

2) IF TURN HALF(IOW, MIDDLE BETWEEN 'FULL OPEN' AND 'FULL CLOSE', LIKE ABOVE DRAWING), IT CLOSES 50% OF WATER FLOW, RIGHT?

16. ### jadnashuaRetired Defense Industry Engineer xxx

Joined:
Sep 2, 2004
Occupation:
Retired Systems engineer for defense industry.
Location:
New England
It depends on how high the flow rate is through the system. It's sort of like asking how high is up...depends on your reference point. As noted, neither a gate valve nor a ball valve are designed or intended to throttle flow - it's either all or nothing.

Use the right tool for the job..it's like using pliers verses a properly sized wrench...it depends on whether you'll ruin it or not, and if you do it often enough, you certainly will.

How wet do you get when you put your finger over the end of a hose? Partially closing a gate valve or ball valve increases the flow rate and momentarily the pressure.

17. ### novice-manNew Member

Joined:
Aug 4, 2009
Partially closing a gate valve or ball valve increases the flow rate and momentarily the pressure ==> where? line (A) or (B)?

18. ### msgaleMember

Joined:
Sep 28, 2006
Location:
Ohio
Pressure in the pipe is governed by pressure of the supply, and the rate of flow thru the pipes.

When no water is in use, pressure is same throughout the entire system, turning valves has no effect.

At very low flow rate, valves have minimum effect.
For two inch pipes in a typical residence, you are very unlikely to have enough flow that a partially closed valve will make any difference at all.

At high flow rates, partially closing valve at a will yield a faster flow thru B