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Topic ClosedPipe size vs. flow rate. vs. pressure drop chart wanted (water)

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kook View Drop Down
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Direct Link To This Post Topic: Pipe size vs. flow rate. vs. pressure drop chart wanted (water)
    Posted: 27-Dec-2001 at 4:34pm
Looking for a chart which has pipe I.D., flow rate, and pressure drop (per 100', for example) - to estimate water pressure drop on 450' level run from street to house, with varying amounts of flow. Street pressure is 50-55psi.

thanks,

Mark
kook@dol.net

Anyone have any links?

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SylvanLMP View Drop Down
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Direct Link To This Post Posted: 28-Dec-2001 at 3:41pm
[QUOTE]In reply to message posted by kook:
Looking for a chart which has pipe I.D., flow rate, and pressure drop (per 100', for example) - to estimate water pressure drop on 450' level run from street to house, with varying amounts of flow. Street pressure is 50-55psi.

thanks,


Are we using K L or M tubing, what flow rates in GPM are we looking for and we must keep the velocity under 8 FPS.

Now for the real confusing aspect of figuring friction losses

Besides developed length what type of fittings and valves are we going to use globe Vs gate or Ball valves?

Are we going to use this supply strictly for fire suppression or domestic use or a combination of both?

Here lies the problem that design plumbers face.

Lets say we are using copper tubing and we use the NFPA standard 13 this sets the friction loss coefficient "C" for copper tube at 150

If we were to use the Hazen-Williams formulas for copper tubing the "C" factor would be 140

By using the 150 factor the results generated would be close to the D'Arcy-Weisbach or similar variations of the Fanning friction loss formula.

So here we have the same material having various friction losses by various code bodies.

If you know the exact application and material that narrows your quest considerably.

Why not contact the CDA or Steel piping institute Or if you have a United Association (U/A) apprenticeship training program near you contact the 4th year apprentice instructor as all these formulas are taught to 3rd and 4th year apprentices and they may have student hand outs (charts)

If you want send me a private E mail and possibly I can put you in contact with some of the real experts on my list who know this stuff like the back of their pencil.

Good luck

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SylvanLMP

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kook View Drop Down
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Direct Link To This Post Posted: 29-Dec-2001 at 2:41am
...ummmmmm, I guess I was just looking for a simple "ballpark" answer. I am replacing 450' of 3/4" pipe with either 1.25" or 1.5" pipe - I dunno the type - it's what people here in the US call "black poly" - you can find it at Home Depot, etc... The inner surface finish of all pipes is the same - same material, vendor, etc...
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Harold Hydronic Net View Drop Down
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Direct Link To This Post Posted: 29-Dec-2001 at 6:57am
Ballpark: When going up one size, at the same pressure, the flow doubles. If you go from 3/4 to 1, the flow doubles - to 1-1/4, double again, etc.
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SylvanLMP View Drop Down
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Direct Link To This Post Posted: 29-Dec-2001 at 1:02pm

In reply to message posted by kook:
...ummmmmm, I guess I was just looking for a simple "ballpark" answer. I am replacing 450' of 3/4" pipe with either 1.25" or 1.5" pipe - I dunno the type - it's what people here in the US call "black poly" - you can find it at Home Depot, etc... The inner surface finish of all pipes is the same - same material, vendor, etc...


Ok here we have some information 3/4 pipe at 50 PSI will give you a "flow rate" in Velocity around and a GPM flow around 34.44 GPM

For a 1/1/2 " line at 50 PSI you would have a GPM flow around 140 GPM

This is close as I can get from the top of my head with out looking at charts

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SylvanLMP

This message has been edited by SylvanLMP on 29 December 2001

» This message has been edited by Lorenzo on 30 December 2001

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kook View Drop Down
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Direct Link To This Post Posted: 29-Dec-2001 at 3:09pm
What???? 140 gallons/minute??? That sounds REALLY high.. How about when you add-in the normal length of 3/4" copper pipe run through the house - there's a good 50' run before the 3/4" tee's out into some 1/2" for faucets, spinkler, etc...
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SylvanLMP View Drop Down
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Direct Link To This Post Posted: 29-Dec-2001 at 4:34pm

In reply to message posted by kook:
What???? 140 gallons/minute??? That sounds REALLY high.. How about when you add-in the normal length of 3/4" copper pipe run through the house - there's a good 50' run before the 3/4" tee's out into some 1/2" for faucets, spinkler, etc...

Now your getting the picture HUH? :-)

You asked for a ball park number something out of LEFT FIELD

We did not take friction losses into account (BJ will explain that) We did not consider pressure drops or what other fittings are being used and fixture requirements inside the structure


What we did do is take 50 PSI and a given pipe size and plugged in the numbers as given.

I didn't bother to even try to locate the books as this is basic math for sizing piping

Later when it is really critical we plug in all the factors needed.

If you would like ILL sign you up to my list and you can ask the really professional guy/gals on there lots of hydraulic questions.

You see there are a whole bunch of BJ's out there who do not comprehend how complex a plumbing system can be.

They kind of get confused with facts relating to most fields.

To him piping systems are one size fits all like trailer park plummin.

You gave too little information to give you a fine tuned answer.

What I did was take the pressure you said and figured on the low side 50 PSI flowing through a given sized pipe 1.5 inches would give you about 138 GPM

To find the GPM I had to first find the velocity .BJ will explain how this is done when only pressure is given.

Once we know the velocity and we already know the size of the pipe we just calculate the GPM


For a 3/4 dia pipe with 50 PSI would give you a flow around 34.5 GPM

A 1 " pipe would give you a flow about 61.25 Gallons Per Minute.

Now you can understand why we need to know the actual materials and actual developed length and what are the actual Fixture demands and what probability factor are we using for fixture flow?

Are we going to use 40% of the fixtures or 75%?

Is there a peek demand like a Movie theater when intermission everyone runs to use the facilities. HECK of a pressure drop

Is this piping going to supply any fire suppression piping systems?

What is the actual lowest pressure you can expect? What is the peek pressure you may see on this system?

See how now your already ahead of the so called plumbers out there?

NOW you can fully appreciate home centers even more as the majority of the home owners can do a much better job at installations then the average stumblebum now dabbling in the trades.

The person with intelligence asks the right questions and finds the answers unlike the lame who can only criticize.

Have a very happy and healthy New Year and please feel free to E mail me.

As far as I am concerned this post is closed Feel free to E mail me if you have any questions.


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SylvanLMP

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SylvanLMP View Drop Down
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Direct Link To This Post Posted: 29-Dec-2001 at 4:52pm

In reply to message posted by kook:
...ummmmmm, I guess I was just looking for a simple "ballpark" answer. I am replacing 450' of 3/4" pipe with either 1.25" or 1.5" pipe - I dunno the type - it's what people here in the US call "black poly" - you can find it at Home Depot, etc... The inner surface finish of all pipes is the same - same material, vendor, etc...

See the Above posting?

I thought you said 3/4" 1.25 or 1.5 so I gave you a ball park number BUT I was conservative in my GPM flow.

The problem is you will have to know the exact or close to exact demand as you have to be careful of velocity especially in metal piping systems.

Today a guy puts in a pipe cause that was the way the other guy did it.

You also stated your running a 1/2" pipe to the faucet That is also a misconception as it you look at the speedy riser or the actual faucet connection you will find the flow rate through the faucet seat is a lot less then the 1/2" or even 3/8 supply.

Taking into consideration an aerator maybe installed you just reduced your actual even more and if you have flow restrictors?

See why plummmin is slightly more complex then the average stumblebums know about or do not bother to take into consideration?

Ask the moron why they used a 1/2 Supply to a kitchen faucet and the idiot would say CAUSE THAT'S THE WAY I BE SHOWN not that they actually took time to think and learn something about the field they picked on top dabble in.

Now if someone asked me why I would run a 1/2" line to the kitchen faucet area my answer would be.

1- There is always the possibility of a dishwasher OR 2 being installed and I would not like to have large fluctuations in the piping so I need 1/2 or even 3/4" hot for a possible future

2- A 1/2 cold water line well that is in case someone wants to install an automatic ice maker or a separate water supply to filtered water or possibly a clothes washer may be also connected near the kitchen sink VOLUME is the reason I may opt for a 1/2" line not because it was always done that way

Are we having fun yet?

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SylvanLMP

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SylvanLMP View Drop Down
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Direct Link To This Post Posted: 29-Dec-2001 at 5:08pm

In reply to message posted by Harold Hydronic Net:
Ballpark: When going up one size, at the same pressure, the flow doubles. If you go from 3/4 to 1, the flow doubles - to 1-1/4, double again, etc.

Harold sorry, Close but no cigar.

RULE of thumb possibly. reality nope

40 PSI 3/4" pipe 30.93 GPM

40 PSI 1" pipe = 55 GPM

40 PSI 11/4 pipe 85 GPM (almost 86)

40 PSI 11/2 pipe 123+ GPM

Granted this is not that critical UNLESS your using flushometers or a fire supression system and figuring you "K" factor for each sprinkler head this could be a major problem.

Contact me on our list and ILL send you all the math involved.

You taught me too well guy...

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