Friction loss for funny pipe

[turfman59]

Does any one have the specs for funny pipe? I have been using the Rain bird 1/2" I would like to try assembling some swing joints to get used to doing it before I go out to the site. Also I would like to have a comprehensive number to use as far as friction loss figuring the additional fittings and the pipe. Does anyone have an idea of what the additional friction loss would be with 4 swing joints per zone assembled opposed to just using cutt- off rizors. Lets say were using 45psi dynamic pressure at 12 - 14 gallons per minute on 1 " lateral line... Let me know if this is not clear enough.... Where has everybody been lately.. am I the only guy with questions... I am getting flash backs of my algebra teacher saying " remember the only dumb questions are the ones that arent asked" Oh buy the way I ordered my study guide materials to prepare for the CIC exam in February...
SEEEEEEEEEE Yaah !

[devildog]

You will see a .48 psi loss, for a 10' lenght of poly, with a head using 3gpm. With Regards... devildog

[turfman59]

Where can I find that data, and is funny pipe poly or neoprene. If I look at the hunter book it has ID size of poly at 0.622 I dont think funny pipe is that large?

[devildog]

"Landscape Irrigation" written by H. Warren Johnson. Have no idea where you will find a copy, got this copy in '88. With Regards... devildog

[Ground Master]

I assume your talking about the pressure loss through 2 funny pipe fittings and the length of funny pipe between them (12 to 18 inches of funny pipe)?

I don't think you would even see a loss of 1psi.......

[devildog]

Originally posted by devildog
You will see a .48 psi loss, for a 10' lenght of poly, with a head using 3gpm. With Regards... devildog

3/4 or 1/2 poly 90 or straight male fitting, coming off a tee or 90 (1" or 3/4")? With Regards... devildog

[HBFOXJr]

It boils down to if you have to worry about pressure loss is a swing joint the rest of the job before that point is all wrong.

I limit flow in funny pipe SJ to <5gpm. I upsize all others for park and athletic to 3/4 and 1" based on GPM of the heads.

[turfman59]

If you boil it down its like this, if you fail to plan you plan to fail. I like to knowwhat I am doing before I commit materials to ground If you dont know what the PSI loss is, you are in my opinion flying by the seat of your pants, What is it? If you dont know it how the heck can you design it. If I start with a certain amont of dynamic pressure I want to know before the water is turned on what the operating pressure is on that last head on each zone, or can I comfortably add a head to this zone by up sizing pipe diameter and closing in the irrigation scheduling window..Foxx I appreciate your knowledge and helpful posts but your just dancing around the original question, what is the friction loss for a swing joint assembly at 3 gallons per minute at 45 psi dynamic pressure with a 1 inch lateral at 32' ft spacing??? Simple as that

[devildog]

Originally posted by devildog
You will see a .48 psi loss, for a 10' lenght of poly, with a head using 3gpm. With Regards... devildog

ITS AS SIMPLE AS THAT.........

[turfman59]

1why would i use a 10ft pc of funny pipe.

2 what about the fittings (2)

3 what is the specs of the pipe you are quoting ( what is its composition )

thanks for your posts I apologize for my nit-picking detail oriented mannerisms

[Ground Master]

devildog's 10' pipe loss is about as accurate as you can get......if you assume 12" of funny pipe plus each fitting has a pressure loss equal to around 5' of pipe...........

if you want more accurate numbers, you ought to rig yourself up a test rig

[devildog]

Originally posted by Ground Master
devildog's 10' pipe loss is about as accurate as you can get......if you assume 12" of funny pipe plus each fitting has a pressure loss equal to around 5' of pipe...........

if you want more accurate numbers, you ought to rig yourself up a test rig

Ditto: Thanks Ground Master, was tired of this one, too. With Regards... devildog

[turfman59]

If you get tired of it dont post, or is this your exclusive site? I cant understand what the big deal is, Its a technical question so if you dont have the expertise to speak to it in technical terms, sit out. I've got all day.

[Ground Master]

Hmmmmm........I re-read your original question. You want to know the pressure loss difference between a swing joint assembly and a cutoff riser?

The difference is so small as to be less than a 1psi loss........

So, there is a theoretical difference, however in reality (ie. a sprinkler system) there is no measureable difference.

[HBFOXJr]

Head spacing, dynamic pressure and lateral size are not relevant to this calculation. The assembly in question and the gallons going through it are the only determining factors.

The loss factor suppled by other is correct, hence my remark that a concern about psi loss of one connection vs. another where not worth worry about.

This all leads me to believe that you may not fully understand how loss is calculated.

Basically you have to work both ends toward the middle so to speak. By that I mean you must have known static pressure and a desired dynamic or working pressure at the head. Knowing how many gpm a nozzles flows at the desired working pressure, you can determine preliminary zone sizing based on available supply. It is most common to calculate loss for only the most severe condition meaning the largest zone furthest from the source. Of course if conditions are not equal then the alrgest zone and the zone furthest from the source should be calulated.

The largest zone will determine main size. The largest zone can be used for all supply and main loss calculations.

The zone must be caluclated in pieces as the entire flow does not travel through all zone piping. If the zone was a straight run, all water flows to the first head but after that you progressively lose GPM at each succeeding head. As gpm drops so does pressure loss per foot of pipe. 3 gpm going 35' through 1" pipe doesn't cost you much.

It has been an accepted practice to size zone pipe so that the operating pressure of the highest pressure head didn't vary from the lowest pressure head of that zone by more than 20%. Translated to a desire high of 45psi or a low of 36 psi. On a common HUnter pc nozzle delivering 2-3 gpm that psi differential means about a 10% difference in gpm delivered at the nozzle.

On many residential systems under 15 gpm and piped in all 1", the variation is usally smaller that 20% from high to low. Most likely it will be under 10% because the piping if the piping is branched in different directions after the valve. This results in a pretty efficient system when installed at head to head spacing and with proportional nozzles.

[devildog]

Turfman,

Since your in Michigan you will also need to consider elevation changes.In a nutshell: Just remember every foot of elevation change causes a 0.433 PSI change in water pressure. If your pipe is going downhill add 0.433 PSI per vertical foot you go down. If the pipe is going uphill subtract 0.433 PSI for every vertical foot you go up. The word "vertical" is critical. If the pipe goes up a slope the vertical distance is how high the slope would be if it were straight up, not the length of the pipe! If you don't want to accept my word for it then you're going to have to buy a book on Hydraulics 101 !

Because elevation changes effect the water pressure you will need to take this into account when determining pressure loss. If the area to be irrigated is lower than the water source we will gain pressure, so we may be able to gain some beneficial added pressure to our system. Care must be taken though. You can only add pressure if ALL the irrigation system is lower. If portions of it are not lower, or are higher than the water source, then those portions aren't going to be getting that extra pressure. It is safest to just not add pressure for elevation changes unless you're really sure what you're doing.....?

On the other hand if portions of the irrigation system are higher than the water source you will always need to subtract out the pressure loss created by the elevation gain. Pressure gained can be easily disposed of, pressure lost however, is very difficult to replace. So, for every foot of elevation gain (higher) in the irrigation system, you should subtract 0.433 PSI from the design pressure.

Still confused? Just follow through the steps you've been given in all these posts, you'll be all right even if you don't fully understand why you're doing. Just remember that any time you decide to measure water pressure with a gauge, you need to turn on the water!!!!!! :D With Regards...devildog

[SprinklerGuy]

OH BOY! Another great post about stuff that doesn't much matter unless you are designing a really large yard or park. I rarely do more than 10k of grass so maybe I shouldn't chime in at all.......what the hell, I can't help it:

Who cares.....unless you are running 100 heads on a zone and using funny pipe/swing joints on all of them it won't friggin matter. most zones you will do will have less than 10 heads on them....my guess is you could get away with swing joints instead of risers. And you should anyway, better for the customer. After all that is what we want right? Happy Customers?

I think that brain surgeons should operate on brains and us sprinkler guys should install sprinklers.........once you've done enough of them you will know your limitations as far as gallonage and distance relative to your water source and zone pipe sizing. Than just do it the same every time! I for one do not like to draw or operate on brains, that is why I do what I do.

Thanks, goodbye.

[devildog]

Originally posted by turfman59
If you get tired of it dont post, or is this your exclusive site? I cant understand what the big deal is, Its a technical question so if you dont have the expertise to speak to it in technical terms, sit out. I've got all day.

...........................................:blob2:

[turfman59]

Did I just get flamed?
I felt like you guys were blowing me off, when I read a one line reply and come back still asking questions you must be thinking either this guy is a moron or he just isnt getting it. This is my real concern about swing joints and rotors.

When i look at the bottom inlet of a rotor and see a 3/4 inch opening and then look at the I.D of a piece of funny pipe I get real nervous, I mean a swelling in my throat. then when I look at the I.D of a cut-off risor i think ah much better. I understand calculating friction loss from the outside heads to the inside, thats why I center feed as often as possible instead of daisy chaining like a lot of the guys around here. I am not kidding you guys when I say where I am at contractors just arent doing it as common practice, but then again this is a real undeveloped market as far as systems in place. I think its one of those real conservative markets or else it just has never caught on here.

My thinking is with all the retiring auto workers moving here from Detroit and other Metro areas it will become common practice. When I told my J D landscapes rep that I already purchased a Mini sneaker he told me that I was ahead of 80% of the contractors he deals with, Kind of one of those deals where 20% of the contractors are doing 70 % of the business.

I guess in terms of swing joints i just have to think its only 3 gpm going through this thing and like an earlier post said once you've done enough of them you gain confidence and stick to a standard process Read my lips " no more swing joint questions"

[HBFOXJr]

These guys are right that familiarity breeds confidence. Knowledge, understanding and familiarity breeds even more.

I've run up to 4.5-5 gpm off hose bibs supplied off 1/2" copper for a midget system when no other source was practically. But you have to know how to calulate all the losses to know if this is feasible. However, once you done calcualtions for different circumstances a few times AND done the job and have seen the results worked your in fat city.

[SprinklerGuy]

We surely meant no offense. Just don't want any new wheel inventions, know what I mean? I have a newer foreman that knows all that hydraulic crap and by the time he is done analyzing what he NEEDS to do in order to decide what size pipe to use and how many elbows he can get away with to keep the velocity in check.......my guys have already piped it the right way. May not be exactly 'BY THE DAMN BOOK'....but it will still outlast the owners and the next owners and the next owners without any problems.....


I'm glad you didn't take it personally! Take care.