If it is a symmetrical grid or uniformly spaced tree, then it will not.
However, if it is not uniformly spaced, you have the potential to
increase flows due to slightly more pressure being available at
sprinklers closer to the supply.
It is similar in principle to balancing a rack or deluge system.
Increasing pipe sizes is not always the answer. Some times, you get
better results from decreasing pipe sizing to create a better pressure
balance.
In all likelihood, a typical office project will not see a noticeable
difference going to a slightly larger ID. However, there is always the
exception. I believe that is why Matt is saying that it is best to
calculate it just to be safe.
Travis Mack, SET
MFP Design, LLC
2508 E Lodgepole Drive
Gilbert, AZ 85298
480-505-9271
fax: 866-430-6107
email:[email protected]
On 8/11/2014 8:06 AM, Duane Johnson wrote:
How will the flow increase if all you are doing is increasing the ID to every
pipe?
Duane
-----Original Message-----
From: Sprinklerforum [mailto:[email protected]] On
Behalf Of Matthew Willis
Sent: Monday, August 11, 2014 10:59 AM
To: [email protected]
Subject: Re: Changing Pipe Sizes
I believe we are saying the same thing to a different result. I have replaced a
system from 40 to 10 before and had the bottom drop out as the flow was not
there. It all goes back to the flow test. It is hard to speak specifics to the
copper leak situation as there is far too much info missing. Bottom line, the
pressure will drop yes. The flow will increase.
Inversely proportional and all. Depending on supply, this can be detrimental to a
system as well. You get the same result changing from 1/2"
to 17/32" sprinklers. I have also had to get creative because the larger
orifice robbed my gallons. Also remember, what size riser and backflow? The
increased gallons will cause higher pressure loss in backflow and meter (if
present). If we go 50gpm more due to larger pipe, does this exceed the listed
backflow size/range? So many questions. I believe it still boils down to having to
re-prove the system as they simply do not match.
R/
Matt <--- PROUD owner of Autosprink :-)
On Mon, Aug 11, 2014 at 10:40 AM, Duane Johnson <[email protected]
wrote:
That is the point, increasing the pipe size does not necessarily
increase the required flow. If you are changing only portions of the
system, it will depend on which segment you are changing among other
factors, such as velocity.
However, if you are increasing the ID to every segment in your system,
the overall effect will be a less demanding system. This is inherent
in the Hazen-Williams formula...p=(4.52*Q^1.85)/(C^1.85*d^4.87). Yes,
increasing Q will increase the friction loss in a pipe. But,
increasing diameter will decrease the friction loss in a pipe because
d is in the denominator. More importantly, d is raised to the 4.87 while Q is
only raised to the 1.85.
So, even if Q is increased slightly, increasing the d will have the
larger effect. In this case (a one for one replacement throughout),
increasing the ID will reduce the friction loss and in turn reduce the
overall pressure requirement.
Try it. If you have AutoSprink, use the Wizard to create a tree
system...just click next until it is finished (the parameters don't
matter at this point). Then, start changing the IDs. Remember to keep
the C factor constant (cuz in this example it does not change). If you
are using HASS, take one of your old calcs and replace your existing
sch 40 branchlines with sch 10. Your calc will be less demanding. :)
Duane
-----Original Message-----
From: Sprinklerforum [mailto:
[email protected]] On Behalf Of Matthew
Willis
Sent: Monday, August 11, 2014 9:53 AM
To: [email protected]
Subject: Re: copper pipe vs CPVC
So if increasing the pipe changes the required flow from 100gpm to
200gpm due to the larger size, you do not think this is more demanding?
Would you please change subject line for me/us as gmail is showing
it's butt. Thanks,
Matt
On Mon, Aug 11, 2014 at 8:17 AM, Duane Johnson <
[email protected]>
wrote:
Your statement earlier holds true only if portions of the system are
being replaced. I was under the assumption the entire system was
being replaced, in which increasing diameter will not be more demanding.
And yes, there is more to calcs...
Duane
-----Original Message-----
From: Sprinklerforum [mailto:
[email protected]] On Behalf Of Matthew
Willis
Sent: Monday, August 11, 2014 7:32 AM
To: [email protected]
Subject: RE: copper pipe vs CPVC
There is more to a calc than just pressure. Flow is also part. Why
do you think we are required to pick the sprinkler closer to the
main on a tree calc?
R/
Matt
On Aug 11, 2014 7:23 AM, "Duane Johnson"
<[email protected]>
wrote:
No, no, no. As long as you are increasing the ID along the
primary path, you are not making the calc more demanding.
Increasing the ID reduces the friction loss per ft. and reduces
the overall required pressure of the system.
Duane
-----Original Message-----
From: Sprinklerforum [mailto:
[email protected]] On Behalf Of
Matthew Willis
Sent: Friday, August 08, 2014 7:54 PM
To: [email protected]
Subject: Re: copper pipe vs CPVC
Especially since the I.D. like you said is larger. This often =
more demanding. Bigger is not always better.
R/
Matt
On Fri, Aug 8, 2014 at 4:40 PM, Brad Casterline
<[email protected]>
wrote:
It just occurred to me though Douglas (on a smoke break as
usual) I would be worried that the existing pipe size is per
code, so I would calc it anyway.
-----Original Message-----
From: Brad Casterline [mailto:[email protected]]
Sent: Friday, August 08, 2014 3:30 PM
To: [email protected]
Subject: RE: copper pipe vs CPVC
Both C=150 and the best part is it looks like the I.D of CPVC is
bigger than type K,L, and M copper.
Brad
-----Original Message-----
From: Douglas Hicks [mailto:[email protected]]
Sent: Friday, August 08, 2014 1:41 PM
To: [email protected]
Subject: copper pipe vs CPVC
One of our group homes has leaking copper pipe. The owner told
me their experience is to replace the copper with CPVC. I like
that, faster and easier for us. But, do I need to get the
system re-engineered when changing to CPVC? Can I just replace
size for like size?
The system is 20+ years old so I am going to propose new sprinklers.
Besides, some of the heads are corroded and some have paint on them.
We will also provide a means to test the antifreeze, at present
there is no way to test the solution.
I am going to exclude sheet rock and painting from the job.
Douglas Hicks
General Fire Equipment Co of Eastern Oregon, Inc
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